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HISTORIC STRUCTURE REPORT •I Archeological Data Section I Northern Canal Guard Gatehouse Complex Francis Gate Complex I Swamp Locks I Lower Locks I LOWELL NATIONAL HISTORICAL PARK I ,.I I I I Prepared by Thomas F. Mahlstedt I Division of Cultural Resources North Atlantic Regional Office Boston, Massachusetts for I Denver Service Center Branch of Historic Preservation National Park Service II United States Department of the Interior Denver, Colorado i July 1980 I 1. CCwH®u §©~rm~ 7f!/:;.oo3 )

" ...... --~.· •I B2215-DSC-TNE January 30~ 1981 I I Memorandum To: Regional Director, North Atlantic Region I Prom: .Assistant Manager• Mid-Atlantic/Nor.th Atlantic Team, DSC Reference: Lowell, Archeologieal Research, Pkg. 109, Park General, Northern I Canal and Francis Locks Subject: Transmittal of Report I Enclosed is a report entitled. ulll.storic Structure Report, Archeological Data Section, Northern Canal Guard Gatehouse Complex, Francis Gate Complex, Swamp Locks, Lower Locks, Lowell National Historical Park." It was prepared by Tom Mahlstedt, Archeologist with Cultural Resources Division, North Atlantic I Regional Office.

This is a very thorough report which assesses the existence and potential for archeological remains along the canal system. It meshes well with ~e ar­ chitectural and historical data section, with which it wi.11 be printed. 'I We appreciate the opportunity to work with your office on this project.

I (sgd) Gerald D. Patten Gerald D. Patten

I Enclosure

cc: I WAS0-560-Mr. Holland, w/enc. Supt., Lowell, w/encs.

bee: I NARO-PC, Mr. McManamon, w/enc. NARO-PC, Mr. Mahlstedt, w/enc. NARO-PC, Ms. Booth, w/enc. I FERA-Mr. Robbins, w/enc. \ysc-PG, _w/':11~· ~. D-S1rTNE, Arclieo. Lib., w/enc. DSC-TNE-PIFS, w/enc. 'I TNE:JWPowell:ecs:l/30/81:5545 I I TABLE OF CONTENTS ·

Page Number •I Introduction • 1 Scope of Work. 4 I Methodology ••. 6 I. Northern Canal Guard Gate Complex. 8

I II. Francis Gate Complex •• 15 I III. Swamp Locks .. 28 IV. Lower Locks. 41 I Sunnnary. 51 APPENDIX I - Outlines of Chronological Development 54

I Bibliography • ...... 73 I Figures. • • . •...... 75

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INTRODUCTION • This report contains significant new insight into the development and I existing conditions of the Northern Canal Gatehouse Complex, Francis Gate I Complex, Swamp Locks, and Lower Locks. Research has required inquiries and assessments related to three subfields of archeology: prehistoric, historic, I and industrial archeology. Because of the nature of the nineteenth century development of these sites which represent one of the crowning achievements of

I one of America's foremost civil engineers, James B. Francis, the report has a I decidedly industrial orientation. This condition has arisen not by design but from the context of the existing conditions at each specific location. Because I most industrial archeologists are historians of technology, architectural historians, and engineers, Robbins' Architectural Data Section (1980) and the 1975 survey and

I drawings completed by Historic American Engineering Record (HAER) could be considered

to have completed the industrial archeology of these sites. However, traditionally

the study and recording of the physical remains of industry has given little attention 'I to the below-ground evidence of industry. This, too, has been the situation in Lowell. As project archeologist, I have studied the rapidly accumulating data on

I I the development of the locks and canals, interpreting the often obtuse language of i 1 the historic record, searching for clues which bespeak of the below-grade components of each site, thus developing a framework for predicting the archeological context I at each location. To more fully appreciate the history and technical achievement of a canal, it I must be thought of as a unit. Canals are systems which, by definition, means that they are the sum of their related parts, not merely a flight of locks or reach of

I a canal. A canal may be thought of as one continuous site which is made up of a

series of functionally related sites. There, in fact, exists a hierarchy of systems

within the overall canal system, for each locking station and guard dam represents 'I its own system. The Francis Gate Complex, Northern Canal Gatehouse Complex, Swamp I I

Locks, and Lower Locks each consist of discrete structural and operational •I components which, combined, create functional entities or systems unto them- selves also defining each site's relationship to the overall canal system. I In order to understand the complexitites of the whole, we must first study its component parts. This study, undertaken at the site specific level,

I represents such an effort. Insomuch as each site is viewed as a separate system, I the archeological assessment has focused on individual elemental components which may exist in an archeological context. Though such features as lock chamber walls, I wing walls, canal sidewalls, and the like are discussed individually in terms of developmental history, technological functions, and archeological potential, it I must always be remembered that each is inextricably related to the other in time, I form, and function. Interpretation and analysis of the sequential development of Northern Canal

Gatehouse Complex, Francis Gate Complex, Swamp Locks, and Lower Locks has revealed ' a salient characteristic which is common to all. James B. Francis and his colleagues I were consummate engineering problem solvers. The existing conditions, both visible as well as below-ground features, is a record of continuous engineering change and

I continuity of purpose. The chronological development of each .of these sites rep- I resents the solutions to problems created by the ever-changing needs of Lowell's industrial section. Each site, thus the entire ~anal system, is the product of I recurrent change and adaptions to the development of industrial Lowell. The number of industrial enterprises increased dramatically throughout much of the nineteenth

I century. Besides increasing quantitatively, they were also developing qualitatively I as the rate of industrial innovation dramatically increased the technical proficiency of each industry. Though recurrent maintenance was performed to reset shifting

wall masonry, repaint deteriorated mortared joints, and replacement of locking and 'I I 2 I

~ guard gates, the principal stimulus for change was the desire to continuously I improve the efficiency and water delivery capacity of the canal system. To this end, canals were straightened and stabilized with massive masonry side-

I walls and lock chambers, and dams were modified in shape, fabric, and size. I The potential archeological record may bear witness to this dynamic change, reflecting significant engineering and technological developments through time. I In this light, it is hoped that not only will the identification of potential archeological.features at the specific sites under study be beneficial to park

I management and planners but will also enhance the appreciation for the technological I achievements which.the Lowell canal system represents. I • I I I I I I ~ I

I 3 I •• SCOPE OF WORK I This report was prepared to satisfy the requirements of the Archeologic~.l Data Section of the Historic Structure Report (HSR) for the Northern Canal Gate I Complex, the Francis Gate Complex, Swamp Lock.s, and Lower Locks. The study is classified as a Class C level of investigation. The principal goal of the archeo-

I logical data section is to identify, describe, and assess known prehistoric and I historic resources within the specific areas of the project. A summary of results and conclusions provides a statement on the potential integrity and significance I of the archeological resources. Several forces, acting independently as well as in tandem, have combined to

I put rather severe limitations on the detail to which this report pursued an assess- I ment of prehistoric and early historic resources. The site-specific nature of the study was greatly constrained by having to focus within the highly restricted

boundaries which define each site. Secondly, the extensive nature of land form • modification required in the nineteenth century to develop the sites as part of I the Lowell Canal System has greatly reduced the probability of prehistoric or early I· historic period material remaining in situ. Combined, these two factors all but preclude the likelihood that archeological deposits relating to the period prior I to nineteenth century development exist, thereby confining the archeological potential to the period for which the sites achieve their present historic signifi-

I cance. The report is, therefore, biased toward an assessment of in situ below I grade features and fabric which relate to the nineteenth century development and technological evolution of each site in question. I The inherent value of the subsurface remains which have been identified in this report is that they may reveal a wider range of activities and technological I. achievement than the available written record. However, a characteristic of I archeological resources is that their information content cannot be precisely I 4 I

• described until they have been at least partially destroyed through excavation. I Therefore, a more precise discussion on the information value of these sites is I difficult at this time. I I I. I I • I I I I I I ~ I

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METHODOLOGY

~ The present archeological study combined two primary tasks: background I research and preliminary field reconnaissance. Background research required the review of data pertaining to three disparate

I subfields of archeology; prehistoric, historic, and industrial archeology. I The following specific and general sources were used: 1. Prehistoric site records and archeological reports of the I Massachusetts Historical Commission. 2. Regional, local histories. I 3. Geological, hydrological, and ecological data. 4. Published archeological reports. I 5. Nineteenth Century Canal Engineering and Technology: Method and Theory. 6. Historic Structures Report, Architectural Data Section, John Robbins, 1980.

I 7. Historic Structure Report, Historic Data Section, Anne Booth, 1980 .

8. Lowell Heritage State Park: Transportation System, Ellen Rosebrock, et al. 1980.

• 9. Cultural Resources Inventory, Lowell National Historical Park and I Preservation District. Shepley Bulfinch Richardson and Abbott, 1980. 10. Water Power in Lowell, Massachusetts. Patrick Malone and Larry Lankton, 1974.

I 11. Historic American Engineering Record (HAER) 1975. I Available data from industrial sites are often considerably more complex than those which present themselves to the prehistorian or most historical archeologists. I This was quickly seen to be the case at Lowell. The Baker Library of Harvard Business School, the Special Collections Room of Lowell University Library, and the Proprietors

I of Locks and Canals, contain detailed company records, ledgers, correspondence, photo- I graphs, and site plans. Due to the wide variety and quantity of historical materials, it was deemed prudent to actively collaborate with specialists from other fields.

This report represents the synthesis of the research conducted by others--most notice-

~ ably, Historian Anne Booth--who was reponsible for the preparation of the Historic I I 6 I

• Data Section for the same sites to which this report focuses its attention. I Canal construction is a highly specialized and complex technology. In order to compliment Booth's archival skills and assist in the interpretation of the

I historic record as it relates to this specialized technology, my primary research I activity was that of studying nineteenth century canal construction methods and theory. I The field survey phase of the study consisted of walk-over reconnaissance. This technique identified canal related structural components at two sites and at I least one foundation which relates to one of Lowell's more significant industries.

It, of course, has not verified the existence of others which, based on the historic

I record, are predicted to exist in a subsurface context, and remain within the realm I of conjecture • • I I I I I I ~ I

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I I. NORTHERN CANAL GUARD GATE COMPLEX

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THE NORTHERN CANAL GUARD GATE COMPLEX • The Northern Canal Guard Gate Complex is a multi-component site, parts of I which, in one form or another, have been continuously operating or in place I since 1792. The site consists of a guard dam which contains ten guard .gates or sluice gates, a boat lock, and a gatehouse which serves as a shelter for the I gate-hoisting apparatus. Inextricably associated with the Northern Canal facil- ities are the Pawtucket River Bridge and Pawtucket Dam both having evolved from I structures which predate the Northern Canal. I British Industrial Archeologist Kenneth Hudson, musing over the excellent con- dition of the Rideau Canal in Canada, stated that "If there is such a thing as I archeology in perfect condition, this is it, " (Hudson 1976:97). A similar statement applies to the Northern Canal. Recent detailed studies by Robbins (1980) I have for all intent and purposes concluded the industrial archeology of this site . These structures and their related elements have received careful and thorough • written and visual documentation. Since the site represents an existing operational I structure, there is little which I can add in terms of a traditional archeological statement. The archeological assessment which is offered is focused on the pre- I historic and early historic activities which occurred here prior to the construction of the Northern Canal Gatehouse. However, as we will see, even these discussions

I have been limited to a minimum because of circumstances which mitigate against their I survival in an archeological context. The inunediate vicinity of Pawtucket Falls represents an area of unusually high I potential for prehistoric occupation. The archeological site files of the Massa- I chusetts Historicpl Commission (MHC) identify eight known prehistoric sites in Lowell, two of which exist in relativ~ proximity to the Northern Canal Gatehouse

Complex. Directly across the Merrimack River in Dracut is 19-MD-46, a multi-com- ~ ponent site, which contained Middle Archaic and Woodland period materials. In I I 9 I

• 1932 this site was described as being more than one mile long (Moorehead 1932) I and extends from below the Pawtucket Falls at School Street downstream beyond Beaver Brook (Fig,. 1). The second site, 19-MD-49, is an unknown temporal or

I cultural affiliation and is located ori the south bank of the Merrimack approximately I 1,000' upstream from the falls near the head of the Pawtucket Canal. Early historic accounts indicate the importance of the Pawtucket Falls to the I subsistence and social activites of the aboriginal peoples at that time. John Elliot visiting the falls in the spring of 1648 found "a great confluence of

I Indians engaged in fishing and wild activites" (Cowley 1862:9) reminiscent of I English fairs. David Gookin, Superintendent of Indian Affairs, noted in 1674 that "there is I a great confluence of Indians that usually resort in this place in the fishing season" (Cowley 1862:13) •

Attracted by the seasonally abundant natural resources, peoples probably I• traveled considerable distances to establish temporary communities adjacent to the falls. Anadromous fish, such as shad and salmon, could literally be harvested in I. weirs set at the falls as they proceeded upstream on their spawning runs. The surplus food acquired during these short periods would have lessened the uncertainities I of subsistance activites during often harsh New England winters. Anthropological studies of several Northwest Coast and Alaskan Native American

I groups have revealed that their seasonal subsistence activites played a vital social I function as well as the obvious economic role. Among several of these groups, similar behavior patterns were observed. Separated into small socio/economic groups for the I greater part of the year, they converged at summer fishing camps during which time they engaged in a variety of feasting, dancing, oratories, singing, and other activ- ~ ities which tended to reify cultural identity and affirm social relations and con- I I 10 I

tacts. The seasonal gatherings along the banks of the Pawtucket Falls may have •I served similar social functions. Though the Northern Canal site is a potentially significant location for providing valuable information about prehistoric lifeways, I it is unlikely that such evidence will be forthcoming. Although it is reasonable to assume that prehistoric materials may be buried I by alluvial deposits, especially along a flood prone river such as the Merrimack, such is not the case at Pawtucket Falls. Instead of depositing potentially pro-

I tective layers, the river is actively downcutting through the bedrock at the falls. I The rock banks of the falls area have not been affected by silting which is occurring downsteam which may be providing a protective mantle over prehistoric sites along I the floodplain (Shepley Bulfinch 1980:21-22). The second factor which tends to greatly limit the probability of prehistoric

I materials remaining in situ at the site is based upon a calculation of the known

topographic modifications which occurred dur~ng the historic development of this • site. The construction of the dam, bridge, and above all, the Northern Canal Gate- I house and lock has caused total and irreversible damage to prehistoric archeological resources which may have existed on the southern bank of the Merrimack adjacent

I the falls. It has also greatly decreased the probability that early historic (pre- I industrial) archeological resources remain at this location. By 1726 the original Pennacook praying village, Wamesit, had become a part of I Chelmsford which contained several discreet parishes or settlements within its boundaries. One such community, Falls Village, located on the southeast end of

I the Pawtucket Falls, became an early center of small-scale industrial activity in I an otherwise agricultural community. In 1794 the Pawtucket Bridge, originally known as the Middlesex Merrimack River Bridge was built across the Merrimack from ~ Falls Village to Mammoth Road in Dracut. A 1794 map of Chelmsford shows the I I 11 I

presence of a saw mill at the Pawtucket Falls just below the bridge (Booth •I 1980:Fig. 5). By 1816, Luke Bowers and his sons, Jonathan and James, built a grist mill and saw mill and a wing dam to channel water into the facilities. I An 1821 map shows this mill directly below the Pawtucket Bridge (Booth 1980: Fig. 7). Thomas Hurd, an entrepreneur owning mills near Lower Locks, purchased

I the Bowers Mill in 1821, selling it in less than one year to Kirk Boott of the I Merrimack Manufacturing Company. In order to maintain an effective head of water in the newly enlarged Pawtucket Canal, Boott bµilt a temporary extension onto I Bowers' wing dam. In 1826-1830 the Proprietors of Locks and Canals built a new wooden crib and rubble-filled dam across the entire river at the falls. In I 1833 the dam was raised 2' in height (Booth 1980:190-194; Sheply Bulfinch 1980). Between 1846-47, the guard dam, ten sluice gates, boat lock, and gatehouse

I were built at the head of the new Northern Canal adjacent the Pawtucket Falls Dam

and Bridge. Construction of the facility required extensive land disturbance • that changed the configuration of the river's banks above the falls. Below the I falls and bridge, excavation for the Northern Canal removed the Bowers mill as well as vestiges of earlier operations. At this time, the southerly portion of

I the dam, from Great Rock near the center of the river southward to School Street, I was rebuilt to direct current toward the headgates of the canal. In order to accommodate the Northern Canal Gate Complex, the southern end of the bridge was I also rebuilt at this time. The southern abutment was moved 60' south of its original position and rebuilt with coursed granite which supported a wooden

I superstructure. The width of the remodeled bridge approach was approximately I 28' 6" (Booth 1980:216-222). The construction of the Northern Canal and the head gate facilities was a

prodigious undertaking. Unlike the Pawtucket Canal where a pre-existing waterway, ~ Speen' s Brook, defined the channel, the first 1, 000' .of the Northern Canal was I I 12 I

built through bedrock outcrops and ledge. At any one given time, over 1,000 • workers were employed and hundreds of others were hired as subcontractors I (Robbins 1980:10). I An account entry for September 22, 1847, provides an example of the work force which was deployed on that d~y: 77 masons, 61 stoneworkers, 23 I blacksmiths, 22 carpenters, 12 millwrights, 8 enginemen and firemen, 642 laborers, assisted by 70 horses, 72 oxen, and 7 steam engines (Rosebrock 1980:8).

I A March 1847 entry reflects that of $270,828.95 total spent on construction to I that date, $10,387.78 was attributed to the" ••• ledge over the guard gates." (Rosebrock 1980:14). This figure represents the second largest single expenditure I to date and presumably refers to the cost of the ledge removal and site prepara- tion for the guard dam and guard gates. Combined, these two ledger entries are

I suggestive of the enormous amounts of human energy, blasting, hannnering, and stone

removal required to modify the natural land surface even before the first stones • for the foundation could be set. I A Proprietors of Locks and Canals drawing which has the northern elevation of the gatehouse superimposed over the natural topographical contour, vividly illustrates

I the amount of ledge which was removed from this site in 1846 (Booth 1980:Fig. 193). I The existing historic record provides an adequate account of the degree of land modification which was required to construct the facilities here. When the nature I and extent of human alteration is considered in conjunction with the natural hydro- logical forces which are acting at the Pawtucket Falls, it is evident that any I cultural resources either historic or prehistoric, could not have survived the construction of the gatehouse. The destruction of all original land surface has

I irreversibly and totally destroyed any archeological materials.which may have

existed prior to construction in 1846. The development of this site has been so ~ complete and comprehensive that there exists no land form or surface that could I

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he archeologically tested in any meaningful sense·. The archeological potential •I of the site is derived from an existing, operational structure, and its com- ponent parts. I I I I I I

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•I I I I I I I II. FRANCIS GATE COMPLEX

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THE FRANCIS GATE COMPLEX •I The Francis Gate Complex, as seen by the visitor today, is a product of over 184 years of successive development. Though the first boat lock was built I here in 1796 or 1797, in terms of existing fabric, the site represents a con- siderably shorter period of time. Modifications occurring continuously through

I the years were undertaken generally in an effort to improve the efficiency and I capacity of water delivery to the mills on the Lower Pawtucket Canal. Change in nearly every conceivable form has occurred, ranging from total removal of former I features or structures to on-site relocation and adaptation. Today the Francis Gate Complex represents a amalgamation of many phases of development, though there

I exists a decreasing number of features and fabric associated with increasingly I earlier work. The history of development of the Francis Gate Complex is itself complex. As

with the other sites discussed in the report, only those features which potentially • exist or are known to exist below grade are discussed in terms of archeological I resources. The major archeological features which exist or potentially exist can I be grouped into several major classes: those which are associated with the lock chamber, c~nal sidewalls, retaining walls, and the structural remains of former I buildings. For information on the evaluation of gates, fixtures, and the existing structures such as the gatehouses, the reader is referred to Booth (1980:39-92), I Robbins (1980), and Rosebrock (1980). Another aspect of the archeology of the Francis Gate Complex is the prehistoric

I period. Theoretically, the general location of the site, situated as it was on I Speen's Brook, would have been a potentially sensitive area for evidence of pre- historic settlement. Though possibly a marginal location in relation to sites ~ such as at the Pawtucket Falls or the confluence of the Concord and Merrimack, I

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or even the confluence of Speen's Brook itself and the Concord, it nevertheless I•• may have represented a favorable inland setting from which a variety of supple- mental subsistence activities could have been undertaken, if only on an intermittent I or sporadic basis. However, recognizing the nature and extent of surface disturbance which has occurred at the site since 1796, the likelihood of cultural materials

I existing from the prehistoric period is decidedly low. Yet such potential does I exist particularly as the distance from the canal increases, where less disturbance has occurred. Landfill and grading may have effectively sealed and preserved I materials which could be representative of a poorly understood aspect of prehistoric life. I Boat Lock Chamber I The present configuration and fabric of the boat lock dates to 1881. The lock was constructed in 1850, 1877, and 1881. In 1850, the central portion of

the lock chamber was raised, straightened, and fitted with grooves to receive

• the Great Gate (Booth 1980:Figs. 21, 22). In 1877 the walls of the lower portion I between the Great Gate and lower locking gates were straightened, while in 1881

the upper section of the chamber to the upper locking gates were straightened.

Although a wooden boat lock had stood here as early as 1796 or 1797, by 1822-23

it had become decayed and was replaced with a stone lock chamber which featured I curved walls and was commonly referred to as the "round locks." The construction of this more permanent lock would have left little evidence of the original wooden I chamber. The straightening of the lock chamber in 1850, 1877, and 1881 may not have I required the destruction or dismantling of the 1822-23 rounded chamber. As we will see, at the Swamp Locks where the upper lock. chamber was permanently narrowed It from 24' to 12', the new chamber was merely built within the old, creating a chamber I I 17 I

Within a chamber. There are several reasons why Francis may have wished to • leave the original chambers in place, one being the obvious expense involved. I And as the daily records show, the Proprietors of Locks and Canals were always I cost conscious. But perhaps the most important reason would be based on several engineering principles. As we will see below in the discussion on canal wall I construction, one of the principal determining factors in design of the profile of a canal wall is the desire to minimize water absorption through the canal walls.

I The retention of the older rounded walls would serve to create a considerably I broader and stronger wall and create a highly effective barrier against water percolation and absorption. Booth (1980, Figs. 22, 26, and 30) indicates the I approximate dimensions and position of this lock relative to the present structures at the site.

I The potential existence of this chamber is not only significant in terms of

its early temporal association with the site but also for its relation to the • technological development in the theory and practice of building locks and canals I in general. Although Booth (1980:45) and Rosebrock (1980) speculate that the round locks I may have been experimental at the Francis Gate, their form is not at all aberrant ,I or atypical of lock chambers. Round or oval lock chambers were traditional forms

I in Europe long before the Pawtucket Canal was built. A sixteenth century artist's I rendering of a round lock provides an almost comical view of such a lock in operation (Fig. 2). The Languedoc Canal, the great French canal built between 1666 and 1681, I which extends for 180 miles and connects the Mediterranean with the Atlantic, was originally fitted with oval lock chambers. Oval chambers were believed to produce

I greater sidewall strength. However, they were phased out of general usage as it

was determined that the increased cost of construction and the increased quantity ~ of water needed to fill them was not commensurate with the benefits. An oval I I 18 I

chamber may exceed the necessary quantity of water by as much as one-third that •I of the parallelogram or rectangular lock forms (Cresy 1847:1537). The oval chamber at Francis Gate Complex represents an early lock form which I by the mid-1800s, when Edward Cresy was writing his Encyclopedia of Civil Engineerin_g_, was no longer regularly being built. It is, therefore, somewhat curious that Francis,

I who was by the mid-nineteenth century one of the most prominent men in the field of I hydraulic engineering, persisted in maintaining the round chamber or at least com- ponents of it through 1881. Further, as his personal engineering library (Lowell I Special Collection Library) will attest, he was an avid student and obviously knowledgeable of the latest European developments in lock and canal engineering. I Perhaps the cost of this major extensive rebuilding campaign was more. than the Proprietors of Locks and Canals wanted to expend.

I An additional subsurface feature associated with the chamber walls may exist

behind each of the four hollow quoins. The large stone blocks where each gate is • attached to the chamber sidewalls and turns in its pivot are known as hollow quoins. I These masonry blocks have had holes drilled vertically through them to receive the heel-post or quoin posts which, combined, act as gate hinges. Due to the pressure

I on these blocks when the gates are fully shut or in motion, the strain on the I chamber walls at the hollow quoins is greater than at other points within the lock. To strengthen this section of the walls, some form of buttressing or other I means of bracing may be.incorporated into the back side of the wall at this point (Mahan 1856:331-332).

I Francis' records do not indicate that any extraordinary means of support were I associated with the hollow quoins. However, in 1877, as part of the rebuilding of the lock, the hollow quoins had shifted and required resetting in Portland cement.

It would not be surprising to discover that some form of buttressing was incorporated ~ into the back sides of the quoins during the 1877 rebuilding (Fig. 3). I I 19 I

Canal Sidewalls • The canal prism or cross section around the Francis Gate Complex, both I above the locks and guard dam and below, have undergone considerable change

through the years.

Originally, much of the Pawtucket Canal was flanked with natural earthen

banks, and only in the immediate vicinity of the lock and dam were masonry wing

walls constructed. The term "wing walls" has several specific historic applications.

I In regard to the plan of a boat lock (Fig. 4), wing walls are the outward bending I walls at the head of the forebay and below the tail bay which serve to keep water from working behind the body of the lock (Cresy 1847:1540). I Francis does not distinguish between forms of wing walls; and his usage of the term has often prompted some confusion when trying to ascertain where specific

I walls were built. As Booth (1980) notes, he tends to confuse the issue further by

using the terms "wing spiling" and "wing pilings" also to denote masonry walls. His • continued usage of these terms was even counter to the technically correct usage of I the time as indicated by mid-nineteenth century encyclopedias and probably represents a local or colloquial usage.

I The first reference to artificial walls is in 1822-23 when a vague reference

is made to the erection of a bank wall below the dam and wing walls at the lower

gate of the lock chamber. Lacking more detailed information, I assume that the I wing walls refers to extensions from the tail bay of the lock only far enough down the western side of the canal to prevent water from seeping back behind the lock I chamber wall where it would cause instability. Such a configuration is shown as late as 1856 (Booth 1980:Fig. 22). The eastern wing wall bending back in a more

I classical form is in fact a component of the entire eastern side wall of the island. ~ I I 20 I

The sidew~lls of the channel below the locks and guard dam including the I• southerly end of the island were subsequently built to extend to the Broadway Bridge in 1867. By 1871 increased water turbulence created from the improvements I made to the sluice ways only one year prior necessitated that the eastern sidewall between the guard gates and Broadway be rebuilt and the eastern bank along this I section was graded. In 1893-95 walls on both sides of the canal were rebuilt, and again in 1900 the western walls below the guard gates were straightened and

I rebuilt (Booth 1980:113-115). This project entailed the restructuring of the I southern end of the island. The photographic record for the Locks and Canals has left us with a vivid representation of this work. The existing fabric and con- I figuration of these sections of the site resulted from this work. Continual attempts to increase the efficiency and capacity of the canals led the Proprietor

I of Locks and Canals again to deepen, widen, and straighten the canal below the

locks resulting in rebuilding major sections of sidewalls from below the dam and • lock to the Broadway Bridge. Spoil from blasting and dredging was used as back- I fill behind the newly erected walls, and considerable expanses of land were thus reclaimed, graded, and sold. The present sidewalls below the guard gates and

I locks represent 1900 and 1902-06 wall construction. I The canals sidewalls above the boat lock and the guard gates are products of different projects. Although the records have not specifically noted when the I northern end of the island and the wing wall from the forebay of the lock were originally faced with masonry, Booth (Fig. 22) indicates that by 1856 such was the

I case. I It is not until 1881 that any specific reference to canal walls above the lock and guard dam is made •. It was during the building program of this year that much

of the physical conditions of the site as we see them today were formed. Likewise,

~ it was during this time that much work and developrnen~ undertaken before this date I was dismantled or otherwise altered or adapted. I 21 I

~ In 1881 the northern end of the island was completely reshaped from the entrance of the forebay of the lock around to the guard gates. The reshaping

I of the island greatly reduced its surface area (Booth 1980:22, 30). The princi- I pal concern of the Proprietors of Locks and Canals was now, more than ever, focused on increasing the efficiency of the canal. The form which the reshaped I island took and retains today is an example of some basic hydrological principles. By narrowing or steamlining the head of the island, it served much as bridge abut-

I ments or starlings do, serving as a cut-water which turns the water aside directing I the current in a more economical flow to the sluice gates and also preventing the formation of whirls and the detrimental effect· they have on the bed around the I foundations of the wall (Mahan 1856:211). In 1893-95 extensive dredging operations enlarged, straightened, and deepened

I the canal above the head gate. Again the Proprietors of Locks and Canals were , attempting to achieve the most economical channel possible. There exists a direct relationship between the depth, curvature, and velocity of the discharge or water I flow. The greater the depth and straighter the channel, the greater the delivery capacity (Patton 1895:133-134). The straightening required sidewall construction

I and the spoil from the dredging was used as backfill which was later graded. I The present walls of the northern end of the island and the sidewalls of the canals above the guard gates are from the 1881 and 1893-95 periods. The I method and design employed in the construction of the canal sidewalls and island walls is of particular technical interest and deserves mention here. Because of I their context, the construction of canal walls adheres to a set of theories and principles which differs from those of other wall forms. A canal wall is in many

I respects similar to a retaining wall, the basic configuration of which is based on ~ the theories of stress and gravity, i.e., the amount of inward force exerted from I

I 22 I

the earthen mass behind the wall. However, in canals, the water pressure •I ·contained within the channel relieves the amount of stress of some degree. One of the principal factors determining a canal wall profile is the concern I of absorption and the effect it has on the earth being retained by the wall. One of the major problems which canal engineers faced once a new canal had been

I cut or an old stream altered was the stability of the canal's sidewalls. At I canals such as the Erie Canal earthen embankments were created to stabilize banks and provide a surface for an adjacent tow path. Often a puddling of clay or fine I sand may be laid at the core of the mass to provide security against filtration. Francis' 1881 estimate for the proposed wall of the northern end of the island

I called for a wall which was S' wide at the top and 10' wide at the bottom (Booth I 1980:101). Such a profile was a traditional form for masonry canal walls. Instead of being perpendicular, canal walls are constructed with a batter, or inclined

sloping walls with a rough sloping or stepped surf ace at the back and a base con- • siderably thicker than the top (Cresy 1847:1539, Patton 1895). The purpose of such I a configuration is to deter the filtration of water through the walls which causes I saturation of the soils inducing instability. A series of photographs taken after Francis' time and at another location nearly I documents the entire sequence of how a sidewall was constructed in the late nineteenth century. Figures 5 and 6 show the excavation for the base of the foundation. in

I terms of bearing loads and general stability, a footing on ledge or bedrock is most I desirable (Baker 1889). In this the engineers of the Locks and Canals were fortunate for much of the Pawtucket Canal has a bottom of ledge. Such is the case at Francis I Gate Complex. By excavating the silt and overburden from the old stream bed, a natural stone sill was encountered. A minimum amount of preparation would be required ~ before the wall could be erected. They, therefore, were not required to drive piles I or caissons into the bottom to derive a solid substratum. The remaining photographs

I 23 I

of this series, Figs. 7, 8, 9, and .10, indicate the nature of the canal's • sloping walls and the batter on the outside. Of particular interest is the I amount of disturbance created and the thickness which these walls assume.

I Retaining Walls I Several retaining walls, which actually serve as darns during times of. freshet, have been built on the island and extend onto either banks of the I canal. One of the most dramatic physical changes to the site occurred between

I 1848-50. At this time large quantities of soil were introduced onto the site I creating a 6' high embankment across the center of the island and extending some distance onto the shore from the Guard Gatehouse and the Francis Gatehouse. I On the island the earthen embankment was stabilized by the construction of a rubble wall at its center. Today the top of this wall can be seen angling diagonally

from another retaining wall to the Great Gatehouse (Booth:Fig. 93c). At the northern • end of the embankment a granite ashlar wall extended from the Guard Gatehouse, angling I to the step adjacent to the east side of the Great Gatehouse. In 1866-67 this ashlar I wall was relaid several feet back (south) of its original position, assuming the straight line between the two 'gatehouses that it has today. Footings for the I 1848-50 wall may exist below-grade and a few feet north of its present location (Fig. 3).

I On the western shore, extending west from the Great Gatehouse, the wide I earthen embankment was also faced with granite blocks. Lacking documentary evidence one can only suspect that this embankment also contains a core consisting I of a below-grade rubble wall, probably well puddled on both sides. In 1866-67 some masonry work was also done to this embankment, at which time it presumably ~ assumed its present configuration. On-site reconaissance reveals the existence I of an additional wall which abuts the ashlar wall on its western end. This wall I 24 I

~ may be bareiy seen at the end of the small car lot for the Francis Gate Complex. I Only an 18' portion of this wall is visible as the western end disappears into the filled area in the vicinity of where the Gate Keepers House once stood. A I 1936 photograph (Booth Fig. 69) shows this wall standing well above grade, further indicating the degree of disturbance and fill which has occurred in this portion I of the site. The 2' wide top of this wall is capped with concrete into which a fence has been set, as is evidenced by the presence of nine evenly spaced post

I holes (Figs. 3 and 3a). Inspection of the below-grade fabric of this wall would I probably assist in determining its construction date and, therefore, significance in regard to its historic association with the overall site. I On the eastern bank of the canal an embankment was also built in 1848-50, presumably this, too, was faced with masonry and likewise was altered in 1866-67.

I Booth (Figs. 70, 71) shows this wall being reinforced with sandbags and fitted

with flashing to reduce flooding. It extended from the Guard Gatehouse into what • had formerly been known as Thompson's Field. The eastern banks of the canal in I this area have undergone considerable change since 1893-95 when the spoil from dredging was used as fill, and the area was graded and sold. The 1879 and 1906

I Atlases show a railroad spur running through this area paralleling the canal. I Booth (1980:Fig. 77) shows this railroad track entering Thompson's Field from Broadway, and Fig. 66 shows the entire area as it appeared in 1929. Today I Madonna Street, which terminates in a cul-de-sac and is lined with several homes, runs through this area.

I The eastern retaining wall possibly exists in its original location extending I from the Guard Gatehouse under fill and the street into a vacant lot between houses numbered 27 and 29 on Madonna Street. ~ I 25 I I

~ Toll Gatherer's Counting Room or Office I A 1839 map (Booth Fig. 14b) reveals the existence of a structure adjacent to the upper locking gates at the head of the island. The first reference to I such a structure is possibly in 1842 when Francis notes that a Counting Room was footed on a mortar foundation. It is not clear whether the 1839 feature

I was temporary and replaced in 1842 with a more permanent one, or if a permanent I masonry foundation was added to the 1839 structure in 1842. During 1881 the northern end of the island was completely reshaped, greatly I reducing its surface area. After this data, the Counting House, which has been constantly recorded on maps since 1839 (Booth Fig. 14a) in 1846 (Booth Figs. 17 and

I 18) and in 1855, 1856, and 1879 (Booth Figs. 21, 22, and 26), is no longer represented. I Francis alludes to the fact that the Counting House was moved but does not indicate where to. Obviously the house had to be moved because there no longer existed enough

ro~m for it at the head of the island. As the above figures indicate, it was a fairly • large structure relative to the size of the island. I As noted above, the construction of canal sidewalls requires considerable I excavation and great quantities of rubble backing to prevent filtration problems. Construction on the sidewalls of the island would likely have impacted a major I portion, if not all, of the masonry foundation of the Toll House. At the same time, not knowing the full extent of the disturbance here one might tentatively I predict that remnants of the western-most walls of this structure may exist below­ I grade (Fig. 3). Toll Gatherer's Residence and Outbuildings

I The Francis Gate Complex included not only the lock, guard dam, gates, and

their associated structures but also an assortment of support buildings and ~ the Toll Gatherer's Residence. Though this may be beyond the present boundaries

I 26 I

~ of the jurisdiction of the National Park Service (NPS), it must be briefly I discussed in order to fully appreciate the site. Sometime before March 1828 a single story Toll Gatherer's House was con­ I structed in a lot west of the boat lock. An 1846 plan (Booth Fig. 16) shows the southern elevation of this cottage. In 1854 the house was raised 2' because

I of water problems, and in 1867 the entire house was raised one story. Between I 1879 and 1906 an assortment of wood frame outbuildings were built north of the house (Booth Figs. 27, 29). A photograph of the western bank, north of the • I island, reveals the presence of two wooden structures and picket fencing which were associated with the working of the complex (Fig. 12). I Though the exact location of these structures is not in evidence today due to considerable landfill and landscaping here, interpolation from maps, such as

I Booth Figs. 10, 21, 27, and Locks and Canals photographs showing the Toll Gatherer's

residence as it appeared in the 1930s (Booth 1980:73, and Figs. 13, 14) could make • the identification of their locations a reasonably easy procedure. (For a more I detailed discussion on the Toll Gatherer's residence see Booth 1980:44-46, 75.) 'I I I I I

I 27 I

I• I ,.I I I I . III. SWAMP LOCKS !I• I I I I I ~ I

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Though the facilities of Swamp Lock have been extensively modified through I• the years, there still exist considerable portions of early-mid-nineteenth century fabric-~some of this is readily visible and some~ as we will see, has I been covered by facings of concrete. The existing fabric taken in conjunction with the potential archeological features of the site provides a detailed record I of the engineering technology and historic development of Swamp Locks.

I Boat Locks

Even before the Pawtucket Canal became operational, the first lock, a singl~

I wooden chamber, burst and was replaced by a second wooden chamber. These first I chambers, which were built between 1792-96, measured 150' long by 32' wide. In 1822-23, with the transformation of the Pawtucket Canal from a transportation I canal to a power canal, Swamp Locks underwent a major metamorphosis of its own. A new 13' high dam equippped with regulating gates was built at the site. To accom-

modate the increased drop i~ elevation, an additional lock pit, the upper lock, was

• constructed with stone-lined walls and a 25' width. The original 32' wide wooden I lock was torn out and replaced with a narrower 25' rubble walled chamber. An 1824 I map (Booth:Fig. 8) is the first representation of the site as it appeared after the 1822-23 construction and reveals the basic configuration which is retained

I today. I In 1840 the locks were narrowed from 25' to 12' in order to minimize the loss of potential water delivery for power to the mills, whose demands for power were I ever increasing. The high cost of stonework lead the Proprietors to favor wooden siding to achieve the' narrowing process. The wooden chambers were built of planking

I with timber braces secured against the wider 1822 stone walls. Ashlar masonry was used to permanently narrow the walls around the gate heel posts. Pine mitre sills \ were used until 1864 when they were replaced by stone sills (Booth 1980:123-131). I By 1859 the wooden inner lock chambers were in need of repairs and were entirely

I 30 I

replaced, maintaining the narrow 12' width (Booth 1980:139-140). •I Plans were made to repair the lower lock chamber in 1885. Project estimates included the comparison of costs for replacing the wooden chamber I in kind or with stone sidewalls (Booth 1980:144-146).' Whether the work was carried out is uncertain. We do know that the lock was never narrowed by I building new stone walls. If this work was performed, the wooden chamber I was rebuilt and never renewed after it had finally deteriorated, for today, the lower lock chamber is the original 25' wide rubble chamber built in 1822-23. I The upper lock chamber was permanently narrowed to 12' in 1892 when new coursed quarried granite sidewalls were set in place. A plan of the proposed I narrowing, drawn in 1890, reveals the relationship of the new walls with the original 25' wide rubble chamber and the timber/plank chamber used since 1840

I to achieve the narrower 12' width. The new walls were designed to be 3' wide

at the top and 4' wide at the base. Apparently at this time, they were also • considering narrowing the lower lock as well (Booth 1980:Fig. 104). I A Proprietors of Locks and Canals plan shows the reconstruction of the side- walls of the upper chamber as built in 1892 (Booth 1980:Fig. 105). This plan

I reveals that the granite masonry replaced the wooden framework but was built I within the 25' wide rubble chamber built in 1822-23. The juxtaposition of the sloping backside of the new wall and the vertical face of the 1822-23 chamber I created a void which was packed with rubble. The retention of the older chamber is an example of Francis' propensity to seek practical solutions to engineering

I problems. Not only did such maneuver make sense economically, perhaps more I importantly, it created a chamber wall which was well suited to retard the detrimental effects caused by water absorption through the walls. ~ No deliberate modification to this configuration has occurred since 1892. I

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However, in 1979, development of the former Lowell-Saco Foundry site by •I Pellon Corporation appears to have impacted the 1822-23 chamber to an undetermined extent. During the excavation of utility trenches on Locks I and Canals property, large granite blocks were encountered and left scattered and partially exposed on the surface. Whether these blocks represent rubble I packing behind the 1822-23 chamber or portions of the chamber wall itself is not known at this time. The potential location of the 1822-23 chamber walls

I is reflected in Figure 15.

I Swamp Locks Dam I The first dam at Swamp Locks was erected in 1800 when an earthen dam or dike was formed in the low ground above the lock. Hale's 1821 map shows a I narrow earthen ridge angling in a northeasterly direction off the north side of the basin (Booth 1980:Fig. 7). The dam served to encourage controlled pondage

by reducing water seepage around the lock when its gates were closed. • In 1822-23 Swamp Locks became the logistical center of the entire canal system. I Its basin became the dividing line between the upper and lower Pawtucket Canal and I also regulated water into the Merrimack Canal which was built at this time. A new dam was built to adapt to the new needs of the canal system. The early records I maintained by the Properietors of Locks and Canals, which in 1822 was linked to the Merrimack Manufacturing Company, are, at best, vague. In them.we are told only

I that the new dam built in 1822-23 was a 13' high stone edifice containing regulating I gates (Booth 1980:123-126). Not quite 20 years later, in 1841, Swamp Locks dam was rebuilt. The stepped I spillway and the deep gate and sluice in the south part of the dam were integral components of this new dam. Also added was the frame structure which still stands ~ above the sluiceway, but not over the hoisting apparatus itself (Booth 1980:131). I I 32 I

In 1859 the dam was extensively repaired by replacing most of its wooden •I elements. The vertical timber braces and the planking flashboards, wastegates, and flashboard irons were all replaced. Apparently some of the stonework of the I dam itself had deteriorated, for repairs in 1859 also included the rebuilding of the camp of the dam at its 1841 height. The narrow pitched roof house was added

I over the entire length of the dam. The small two-bay gatehouse placed over the I deep gate in 1841 was incorporated into this new gatehouse (Booth 1980:135-136). The Swamp Locks Dam was raised l' in height in 1918 (Booth 1980:151; Figs. I 114, 115). In 1945 nearly one-third of the downstream portion of the top of the dam was I severely damaged by a washout (Booth 1980:Figs. 145, 146). Plans drawn in 1945 I suggest that the damaged stonework was not rebuilt. Instead, concrete was poured over this entire section of the dam (Booth 1980:Figs. 145, 146). This section of

the dam also acted as a spillway for the wasting water let through the wooden • flashboards scribed to its top. Since at least 1897 (Booth Fig. 106), and un- I doubtedly before, a wooden apron laid over the rubble stonework had protected it from the fall of the discharging water. The concrete applied over the damaged

I dam acted as a protective covering for the stonework, thus, the wooden apron was I not renewed. The 1945 concrete apron is obviously visibly intrusive and not at all in I keeping with the historic fabric of the dam. Sealed below this concrete covering are the partially damaged remains of the rubble dam which, save some minor later

I alterations, was built in 1841. The configuration and historic fabric of Swamp I Locks Dam are noteworthy as both are expressions of nineteenth century civil engineering technology. ~ I I 33 I

The shape of Swamp Loc~s Dam, basically trapezoidal, was a favored cross •I section form for nineteenth century dams. The shape is similar in design to canal sidewalls, having an inclined back with a suitable batten for strength .I and prevention of filtration (Mahan 1856:325). Functionally, the Swamp Lock Dam was a "clear overfall to apron" form of construction. The wooden apron

I which was removed in 1945 is historically an integral component of this dam I style. The wooden aprons resist and break the fall of the water wasting through or over the gates. I The timber receives the force of the fall ~rotecting the rubble stonework and decreases the amount of turbulence by delivering the water past the dam on its

I sloping planks (Patton 1895:691-692). I Patton, in his 1895 Treatise on Civil Engineering, notes that uncoursed rubble masonry was used on masonry dams, weirs, and spillways (Patton 1894:686). It was

felt that the irregular and random shapes of rubble created a technically superior • bond to that achieved by ashlar masonry. Civil engineers, therefore, favored rubble I stonework where there was turbulent or high velocity water such as around dams, weirs, spillways, and wasteway sidewalls. Ashlar work was deemed acceptable for

I lock and canal sidewalls.

I Wing Walls, Wasteway Walls, and Retaining Walls I During 1822-23 Swamp Locks was the focus of intensive development. As we have seen, during this period, the rubble dam and lock chambers assumed the basic I configuration which they retain today. Coincidental with this development was the construction of various sidewalls around the basin and below the dam. The

I historic records, however, do not specifically indicate all of the work which was

undertaken at this time. We can only assume that the repairs made in later years t. were being made to walls first erected at Swamp Locks during 1822-23 (see below). I

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The records do document the construction of one major wall at the site in 1822-23. • At this time, the sloping northern side of the narrow island separating the locks I and the wasteway below the dam was faced with a substantial dry laid wall. As 'I noted earlier, the use of rubble stonework on wasteway walls was a basic tenet of nineteenth century civil engineering technology. I Numerous walls were built or repaired in 1854. A major wing wall connecting the north end of the dam with the wall at the head of the Merrimack Canal was

erected in 1854. The wall was footed on ledge and measured approximately 11' in

height and 1-1/2' thick and was built of concrete with gravel puddling on either

side (Booth 1980:132). Traditionally, canal walls were constructed of stone, the I use of concrete as the sole material for such a wall in 1854 must represent an early experiment in the application of new building materials.

Francis recorded that the wall on the south side of Swamp Locks Dam was repaired

in 1854. The work entailed the removal of the puddle behind what Francis termed an

"ashlar wall." As Booth notes, ·Francis' use Qf the term "ashlar" is what we would I term "rubble" today. He goes on to note that the puddle was replaced by a backing of concrete approximately 2' thick and that the upper three or five courses were

I reset with solid backing (Booth 1980:132). Booth interprets that this work occurred I to the wall on the north side of the island, the wasteway wall. This wall was built in 1822-23 of dry laid granite rubble and though settling and some wall fall has I occurred, it remains in reasonably good condition. I was unable to physically inspect the fabric of this wall to determine whether concrete backing can be

I detected in the gaps created by dislodged stone. If such a condition does not I exist, I propose an alternative interpretation for the location of the wall repaired in such a manner. Francis may have been referring to the wing wall or

bulkhead between the head of the upper lock and the southern end of the dam. If

I 35 I

such was the case, evidence of this would not be present today, for in •I 1927, a sluiceway was built through the stone bulkhead which was then replaced by a concrete bulkhead (see below). Supporting this second I alternative was additional way repair which was performed in 1822-23. Francis states that "on the south side of the lock there is a similar

I ashlar work spiling resting on rotten ledge .•• " (Booth 1980:133). He I is referring to the south wing wall which bent back from the forechamber of the upper lock, its counterpart was the bulkhead between the lock and I dam. The configuration of the Swamp Locks basin was different in 1854 than it is today. The present shape was achieved in 1894-95 with the addition of I landfill (see below). In 1854 a wing wall extended in a southwesterly ·direction from the forechamber of the upper lock (Booth 1980:Figs. 94, 95, 97, 98, 99,

I 100, 101, 103). The work performed on this wall in 1854 included the removal

of the puddle1 behind the first 20' (from the south heel post) of the rubble • wall, replacing it with concrete to a thickness of 3'. The remainder of the I wing wall, south of the stone section, was constructed of wooden piles; here too the puddle backing was removed and replaced with the 3' thick concrete

I wall, apparently leaving the piles in place. Only five years later, in 1859, I the upper 6' of the south wall had shifted, needing repair. This top section was rebuilt with cemented sloping sides (Booth 1980:134). I During 1894-95 major renovations transformed the Swamp Locks basin into what a visitor sees today. A new granite wall was built from the south fore-

I chamber wall of the upper lock to the head of the Hamilton Canal. At points I 1. Puddle is clay to which a little water has been added and which is then tempered by kneading (usually trampling) the mixture which increases ~ its plasticity. I

I 36 I

the new wall was as much as 30' from the then southern wing wall repaired •I in 1854 and again in 1859. The introduction of landfill enabled the Pro- prietors of Locks and Canals to reclaim approximately 1/2 acre of land onto I which the Foundry of the Lowell Machine Shop rapidly expanded. The basin transformation is clearly portrayed in a Locks and Canals drawing (Booth

I 1980:139a) which illustrates the new wall and land between the Hamilton I Canal and the upper lock. Additionally, the dotted line running southerly through the Lowell Machine Shop corresponds with the approximate location I of the original south wing wall. The effect which this site development had on the original wing wall is unknown. It is possible, though admittedly I unlikely, that a small section of this wall remains in place immediately adjacent and extending south from the south heel post at the head of the

I upper lock (Fig. 15) •

Also in 1894-95 a granite and wood ramp was built into the new wall at • a point approximately 45' upstream from the head gate of the upper lock. In I 1896 the ramp leading into the Lower Pawtucket Canal was built. This ramp i1 may be seen today on the north side of the lower lock (HAER 1975). During the 1890s reaches of the canal were straightened and most of the canal system I was provided with stone sidewalls. Ramps, such as the one incorporated into the walls at Swamp Locks, provided the only means by which men and equipment I could be deployed to carry out periodic work on the canal bottom (Booth 1980:145-150). Portions of these ramps remain in place today.

I In 1918 the Swamp Locks dam was raised l'. This required that the concrete

1 I wing wall at the north of the dam, built in 1854, also be raised by 1 , at which time it was also refaced with concrete (Booth 1980:Figs. 115, 116). Like- ~ wise, the rubble bulkhead between the head of the upper lock and the south of I I 37 I

the dam was also raised l' and given a concrete facing (Booth 1980:Fig. 114). •I Between 1927 and 1928 a new sluiceway commonly known as the "wide gate" was constructed at the head of the narrow island between the south end of the I dam and upper lock. In order to accomplish this, the original rubble bulkhead was torn out and the sluiceway excavated through the head of the island and

I the 1822-23 rubble wasteway wall where the effluent passed into the wasteway

a few feet below the concrete apron of the dam. A Locks and Canals photographer

documented this work as it progressed through its various stages (Booth 1980: I Figs. 133-137). The rubble wall on the north side of the wasteway received a concrete

I facing in 1942 (Booth 1980:157:Figs. 143, 144). Presently it is not known when I this rubble wall was first erected • Tool/Watch House • Since 1852, a small building has been represented at various locations on the island between the upper lock and the wasteway. An 1852 site plan reveals

a structure situated approximately 30' to 40' east of the head of the island

(Booth 1980:100). By 1891 a building of similar proportions appears perched

at the very head of the island (Booth 1980:Fig. 103). Between 1892 and 1927

I it stood at a right angle to and slightly east of the house over the dam and I appears to have straddled the south wasteway wall (Booth 1980:Figs. 105, 114, 131). In 1927 this structure, labeled as "L & C Tool House" on a site plan I (Booth 1980:Fig 131) was again temporarily moved while the "wide gate" was constructed. After the "wide gate" sluiceway was finished, the Tool House

I was returned to its 1852-1927 site a few feet east of the south end of the

dam (Booth 1980:155:Fig. 140). Some time after 1936 the house was moved to ~ its present location where it has served as the Gatehouse for the "wide gate" I hoisting apparatus ever since.

I 38 I

Site inspection identified the former location and means by which the •I Tool House was footed before it was moved to its present location over the hoisting apparatus. Hidden in the undergrowth to the east of the house are I three piers made of brick which are evenly spaced 7-1/2' apart (Fig. 16). These small brick features represent the footing blocks for the southern

I side of the Tool House when the house was oriented with its long axis on an I east/west orientation (at a right angle to its present position). The northern foundation is represented by an 18' long timber beam which is poised on the top I of the southern wasteway wall. The 12-1/2' width and 18' length of this rather makeshift foundation correspond exactly to the dimensions of the Gatehouse.

I Further, paint identical in color to that of the Gatehouse exists on the timber I and footing blocks indicating that the house had received a coat (if not its present coat) of paint while at this temporary location (Figs. 17, 18) • • Saco-Lowell Shops Annealing House I The Swamp Locks site also contains remnants of one of Lowell's earliest and most significant industries. Historically, the Lowell Machine Shop was situated

on the north side of the Pawtucket Canal at Swamp Locks. First established in

1824 as the Machine Shop of the Merrimack Manufacturing Company, it was later

I sold by the Proprietors of Locks and Canals to the Lowell Machine Shop in 1845 I to help defray the cost of constructing the Northern Canal. Between 1911-12 the Lowell Machine Shop was the largest of four machine manufacturers which merged I to form the Saco-Lowell Shops. By the late 1920s the yard was closed and in 1932 the Machine Shop yard on the north of the canal and its Foundry south of

I the Locks were demolished (Booth 1980:Figs. 140, 141).

During the 100 year history of the Lowell Machine Shop, it played a signifi- ~ cant role in the ·industrial development of Lowell by manufacturing machinery for I

I 39 I

2 Lowell's leading industries. A series of plans and artistic views illustrate I• the chronological development of the Lowell Machine Shop between 1845-1900 (Figs. 19, 20, 21, and 22). Located adjacent to the north end of the dam can I be seen the evolution of a structure which by 1893 (Fig. 21) featured a large chimney at its western end. This structure is identified as the Annealing

I House in the 1900 plan of the Lowell Machine Shop yard (Fig. 22). An 1897 I photograph shows the Annealing House adjacent the entrance to the Dam House. By this time wooden additions had been attached to its southern side forming I an overhang over the north wasteway wall (Booth 1980:106) a condition also reflected in the 1921 plan of the site (Booth 1980:Fig. 118). A 1918 photo-

I graph of Swamp Locks taken after the dam had been raised l' provides a complete I view of the Annealing House and its association with the Swamp Locks dam and Building No. 2 of the Machine Shop, the massiv~ structure in the background

(Booth 1980:115). Yet another view shows the Annealing House as it stood prior • to complete demolition in 1932, with its chimney standing over 100' in height I (Booth 1980:140). I The existing physical evidence for the Annealing House is in the form of several partially exposed concrete foundations. Only a portion of the foundation I exists on Proprietors of Locks and Canals property, the remainder extends under a small macadamized parking lot behind one of Pellon Corporation's new buildings

I (Figs. 15, 23, and 24). I I i 2. A detailed Report of the Corporate History of the Lowell Machine Shop I is included in Shepley, Bulfinch, Richardson, and Abbott 1979 Lowell National Historical Park and Preservation District; Cultural Resources Inventory, Inventory Forms and Research Reports, Industrial: Lowell Machine Shop Site I through Massie Falls Industrial Site. 40 . . . -- . ..., - -~·· ·. I

•I I I I I I I ,, IV. LOWER LOCKS ,I

:I I I I I I ~ I.

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Lower Locks •I The site of the Lower Locks is comprised of several functionally and historically related components. It consists of a flight of two navigational I locks and a dam with sluiceways, gates, and gatehouse which exists at the western end of the upper locks. Lower Locks was first developed in conjunction I with the construction of the Pawtucket Canal, originally a transportation canal, in 1792-96. Despite the antiquity of the site, the historical records pertaining

I to site development through the years are relatively shallow in comparison with I those of Swamp Locks and the Francis Gate Complex. Like these two sites, Lower Locks today is the product of continued repair or replacement of the various I constituent elements of each component of the site. However, Lower Locks did not undergo the intensive late-nineteenth century change which substantially

I altered conditions at other locations. Lower Locks has undergone relatively

minor change compared to these sites. • Though some twentieth century work such as the visually intrusive concrete I siphon spillways are readily visible, much of the early nineteenth century fabric exists, with evidence of the 1823-24, 1841, and 1887 periods being particularly

I well represented. I Much of the change which occurred at Lower Locks was on a periodic basis and was superficial and temporary in nature, involving replacement of wooden gates, I wooden spillway aprons, and wooden lock linings. This change involved materials which were susceptible to rapid deterioration through use as well as mere exposure

I to the natural elements. In essence, much of the site work has involved the I temporary replacement of temporary fabric. The surface area occupied by the site is and was historically strictly

limited by defining boundaries. Development of industrial enterprises on the ~ north and south sides of the site has been intense and vital to the overall I I 42 I

context of Lowell's industrial growth. However, this development has not •I infringed on property held by the Proprietors of Locks and Canals. As various maps show (Booth 1980:Figs. 159, 162, 165) to the south of the locks themselves I a narrow strip ·of land was maintained as a buffer zone. This strip undoubtedly represents the vestiges of a tow path, the maintenance of which was mandated by

I the original charter in 1792 (Booth 1980:7). I On the north, Locks and Canals property was even more restricted, being limited to the wasteway wall and northernmost end of the dam. Maps of the area I (Booth 1980:Figs. 159, 162, 165) illustrate that the Prescott Mills attempted to maximize their operating space, having built the cotton room directly above the

I northern wasteway wall. A photograph taken in 1932 shows the nearly claustrophobic I proximity which the Middlesex Company Mills (right) and Prescott Mills (left) had a·ssumed prior to their demolition (Booth 1980:Fig. 174). Significant though these

operations may be, their existence beyond the specific boundaries of the Lower • Locks sites places them beyond our immediate archeological concern. (For a I detailed discussion refer to Booth 1980:159-163.) I Of potential archeological interest at a location such as Lower Locks, situate.d as it is at the confluence of a stream and a river, is the question of prehistoric I activity and to what extent such activity may exist in the archeological record. Theoretically, the topographical characteristics of the site could be considered I a potentially favorable location for prehistoric activities, if not in the form of more permanent occupation at least serving as the basis of intermittent

I subsistence activities. However, as noted above, the site is extremely small in I terms of surface area and the area that does exist has been subject to the vagarities of construction disturbance.

The narrow strip of land existing at the southern end of the site has itself

~ undoubtedly undergone extensive disturbance during the excavation of the lock pits I I 43 I

and subsequent building of southern walls of the chambers. The construction •I of canal and lock walls, as we have seen above, is primarily determined by the need to restrict the detrimental effects of water absorption. The technological I answer to the problem was the construction of massive walls designed with a sloping back side or· batten and backfilled with enormous quantities of rubble.

I Such a configuration is poignantly illustrated by Figures 5-10, which also I indicate the extensive degree of disturbance which occurs in the immediate vicinity. The likelihood that prehistoric resources exist in any form, either I in situ or in a disturbed context, is severely limited by the construction of these lock walls. The successive phases of facility development has confined

I the archeological sensitivity of the site to that of Lowell's industrial history. I More specifically, the archeology of Lower Locks relates to developments in the technology of canal and lock construction •

To follow is a discussion of those features which, based on historic records • and site reconnaissance, are predicted to exist in an archeological context. Some I of these, such as remnants of early lock chamber sidewalls, are evidence of I technological change through time, while others, such as the rubble embankment below the locks, and replacement of wing walls probably reflect repair or I replacement of deteriorated features. I Boat Locks The Lower Locks site has contained navigational locks since 1792-96 when I two wooden chambers, each measuring 150' long by 32' wide, were constructed as part of the original Pawtucket Canal. There is some evidence, though admittedly

I small, that a third lock chamber may have been constructed here sometime between

1802 and 1821 (Booth 1980:16-17, 159). No details of this development have been ~ found other than J. G. Hales' 1821 map which shows a flight of three locks existing I at Lower Locks (Booth Figs. 7, 153).

I 44 I

By 1823 the original wooden locks were severely deteriorated and the •I building campaign undertaken at this time achieved the basic configuration which the site exhibits today. In 1823 two lock chambers fashioned with I stone sidewalls replaced the earlier two or possibly three wooden chambers. The records of the Merrimack Manufacturing Company actually tell us that the

I timber of the older locks was physically removed prior to construction (Booth I 1980:164, 166), precluding their existence in an archeological context. The existi~g rubble walls of the entire 25' wide upper lock chamber and only the I upper portion of the lower lock chamber are vestiges of this period. In 1841 the locks were narrowed to 12' by constructing timber planks and frame chambers

I within the wider stone chambers. Also in 1841, the walls around the gate pockets I were permanently narrowed to 12' by ashlar work. Als'o at this time, the lower section of the lower lock chamber was permanently narrowed to 12' by laying the

ashlar walls which exist there today (Booth 1980:172). It is possible that the • lower portions of the original 25' wide rubble lock remain in place extending I to a depth equal to the bottom of the chamber (Fig. QS). This prediction is not I based on any evidence pertaining to the site itself, but rather from the technique used in 1892 to narrow the upper lock chamber at Swamp Locks (see above). The

removal of this lower section of the 1823-24 rubble lock wall would have been

structurally unsound in regard to the bearing load of the walls. Additionally, I it would have been counter productive in regard to minimizing water absorption through walls, a problem which would have been greatly alleviated by retention

I of the original wall, thus creating a formidable barrier for water to pass. An I entry in an 1842 ledger indicates that a material termed "Macadamizing stone" was used under the flooring of the lower lock chamber (Booth 1980:175). Pre-

sumably this refers to gravel used to puddle the foundation for the bottom.

I 45 I

Although the inner wooden chambers were renewed in 1860 (Booth 1980:178) • and again in 1876 (Booth 1980:184-185) they no longer exist, leaving the locks I essentially as a combination of 1822-23 and 1841 construction. I In 1852, 1877, and 1878 experiments measuring the current flow through the locks required that the mitre sills for the gates be pointed and repainted with I Portland and American cements. (See Booth 1980:178 and 187 for details.) Due to frequent low water conditions on the Concord River, the easterly half

.I of the lower lock was deepened by 2-1/2' in 1905 (Booth 1980:189a). A photograph I at that time suggests that in order to achieve an additional 2-1/2' in depth, the bottom was rounded (Fig. 26). The so-called "inverted arch" bottom was a typical I nineteenth century configuration which was used to resist the upward pressure of water under the bottom and "to distribute the weight of the wall over the portion

I of the foundation under the arch" (Mahan 1856:330). Figure 27 also indicates

that dredging occurred below the locks themselves. The bottom of the upper lock • chamber has been altered more recently. In 1910 a 24" drain pipe was laid from I a valve on the island above the dam beneath the entire length of the lock to its eastern end where it empties water into the lower chamber enabling the lower

I Pawtucket Canal to be drained (Booth 1980:189a:Fig. 184 and 185).

I Lower Locks Dam Details of the first dam which was constructed in 1823-24 are lacking, but

I a ledger entry made at the time indicates that from the beginning it contained I sluice gates (Booth 1980:164). Other vague entries such as "filling in at the dam, Lower Locks" and " ••• levelling off back of dam ••• " (Booth 1980:165) I suggest that the dam was earthen, or partially earthen over a rubble core with sluice gates set into it. ~ I

I 46 I la In 1841 portions of the dam were reconstructed. The clapboards gatehouse over the dam and the large sluice gates near the northern end of the dam may

I be aspects of this building (Booth 1980:174-176) as is the straight sloped I apron still evident in the center of the dam (HAER 1975). This apron is presently covered with a wooden platform which has been recurrently replaced I thr'ough the years • In 1887 the dam was essentially rebuilt when all of the 1841 gates and

I sluiceways were replaced (Booth 1980:187-188:Fig. 160). I The last major alteration to the dam occurred between 1946 and 1950 when three concrete siphon spillways were built over portions of the eastern (down- I ·stream) side of the dam. (Booth 1980:189a:Figs. 177, 178, 184, 186a.)

Wing Walls, Wasteway Walls, and Retaining Walls

The existing rubble walls on either side of the wasteway were built in

1823-24 when the lock chambers were first constructed of stone and the first dam

was built. Technically, the north chamber walls of the two locks and the southern

I wasteway walls are a single unit. However, there is no information which indicates I whether this is a free standing feature entirely of human manufacture or whether there exists some natural land form at its core, having merely been faced with I stone on either side. The fabric employed in the wasteway walls may be indicative of the state of

I technology of the time. I The wasteway walls are of rubble construction. As noted earlier, rubble walls were often favored for wasteway sidewalls, dams, and spillway surfaces I because such masonry was believed to be particularly well adapted for the structural problems which the turbulence and velocity of waste water could ~ cause to such features. I I 47 I

Vag~e references to work performed in 1841 indicate that the wall on • the north side of the race to the dam was built and that an old sidewall I near the dam was removed, and the stone reincorporated into the new walls I being built (Booth 1980:175). Prior to 1860, the wing walls at the south and north ends of the dam I were built of wooden pilings. In 1860 the wooden south wing wall, which also serves as the upper wing wall and portion of the forebay of the upper lock,

I was reconstructed in stone. The account of the work is not entirely clear I and is reproduced here in its entirety: September, 1860. Replaced the piling on the south side of the headgates of the Lower Locks. Took up the old plank piling for 20-1/2 feet from the recess in the wall, to a depth of 7 feet I 8 inches, to a good southern pine plank piling driven by hand when the locks were rebuilt in 1841. A stone and cement wall two feet thick was built up beginning about one foot below the top of the south pine pl,ank piling (Booth 1980: 179 from Francis, Records A, p. 229, September 1860).

This passage suggests that remnants of the wooden wing wall built in 1841

may exist below the stone work which presently characterizes the southern wing

I wall of the upper locking gates (Fig. 25). I The repair of the wing wall at the northern end of the dam undertaken in 1861 appears to have entailed work of a different nature and the description I and sketch is also .reproduced here:

The wooden piling between C & D in the sketch belo~, having become decayed, it was repaired yesterday, by building the I cement work shaded with black ink in the sketch. The piling shaded with ·red ink is of brick; that between C and D was built when the Dam was repaired and heightened in 1841. The top of the brick work is about 5 feet below the top of the wall, being nearly at the level of the camp.of the dam. It was laid in a reddist coloured English cement, now-very hard; above the brick work the piling was of wood and had become very much decayed.

I 48 I

The piling between D and E was built when the Prescott 1·• Cotton House and Boiler House were built in 1845; it is capped with stone at the top of the ground, and in part exposed yester­ day no crack of other imperfection could be discovered. The wall built yesterday was of stone, principally mortar stone, laid in I New York cement3 of which 27 barrels were used (Booth 1980:179 from Francis, Records A, p. 231, July 1861). I I: Plan View I j I J I I " Profile (after Booth 1980:180) I• I Though not rea9ily evident today, such a wall configuration may be

I present at the north wing wall, though it would have been partially impacted I by the laying of a 24" drain in 1910 (Booth 1980:Fig. 184). An additional wall (walls?) was identified during on-site reconnaissance. I Surface evidence indicates that the sloping embankment extending from below the lower lock to the Concord River was formerly faced with rubble or perhaps tra-

I versed by several walls creating a terraced effect. A few exposed segments of

~ 3. New York State was a leading producer of natural cement, a cement used primarily on masonry subjected to moisture yet requiring a high degree of strength. All of the masonry of the Erie Canal was set in New York cement after 1891 I (McKee 19 7 3: 69) • I 49 I

what appears to be a wall underlying quantities of debris on this slope I• suggests that this embankment may have been faced with stone in an effort to impede bank erosion (Fig. 25).

I' Watch House or Tool House and Other Associated Structures ,, A small Tool House or Watch House was situated at the northeast end of the dam. It is represented in a drawing for the first time in 1855 (Booth:Fig. 1570) 1· and is mentioned for the fist time in 1865 when it was reshingled with Kyanized spruce shingles. Sometime between 1870 and 1896 this structure was removed from

I the site. A 1903 drawing of the site shows a facility of the Prescott Mills, I identified as the "Cloth Room" situated on the top of the north wasteway wall extending into the area where this Tool/Watch House was located previously I (Booth 1980:Fig. 165). Today the entire Prescott Mill yard is a parking lot. Though structural remains of the Prescott Mill may have been sealed by macadam,

it is highly unlikely that any evidence of the small foundations for the Tool/ I• Watch House would have survived, much less be identifiable, as such. A second structure was also formerly associated with the Lower Locks Dam. I A small narrow building was situated at the head of the island between the southern end of the dam and the upper locking gate of the upper boat lock. In I 1855 it is represented for the first time at the site (Booth 1980:159) and again in the City of Lowell Atlas of 1879 (Booth 1980:159). A series of photographs

I (Booth Figs. 169, 171, 173, 178) reveals the structure to have been single-story I building with clapboard sides, a steeply pitched roof with a gable front and with a small chimney at the front of the roof ridge. This structure was removed I sometime after 1946 (Booth Fig. 178) after having been a part of the complex for nearly 100 years. The structure had been built on the large granite blocks which I. form the head of the island. When the house was removed no evidence of its I former existence was left. I 50 I

Summary I• The combined results of the background study and walk-over reconnaissance here identifies a number of various archeological features at three of the four I sites under investigation. These features are grouped into two major categories-- Known and Potential Archeological features--which are based on.the degree of

I certainty with which they have been identified. Walk-over reconnaissance has I identified the existence of several features. The historic record has assisted in predicting the existence of others, which must remain conjectural until sub- I surface conditions can be inspected. Summarized below are the specific features which are knowri to exist or I potentially exist in an archeological context at the Francis Gate Complex, I Swamp Locks, and Lower Locks. I. Francis Gate Complex

A. Potential Archeological Features

1. 1822-23 Round Lock: portions of the curved walls of this • first masonry lock at this site may exist behind the existing I straight walled lock. 2. Quoin buttressing. There may exist some form of buttressing or extraordinary support behind each of the four hollow quoins I of the lock chamber.

3. 1848-50 retaining wall foundation located a few feet north I of the ashlar wall which extends between the Guard Gatehouse and the Francis Gatehouse evidence of the foundation or trench for the original retaining wall which was built here between I 1848-50 may exist. 4. East bank retaining wall. On the east bank of the canal extending from the Guard Gatehouse to a vacant lot on Madonna Street a I retaining wall built in 1848-50 and modified in 1866-67 may exist buried below fill which was placed here after dredging in 1893-95. I 5. Toll Gatherer's Counting Room. Between 1839 and 1881 a Counting Room or Toll House existed at the northern end of the island adjacent to the present upper lock gatehouse. Remnants of the ~ western walls may exist below-grade. I I 51 I

6. Toll Gatherer's House and outbuilding. In the lot directly west of the Francis Gatehouse lying buried below-graded fill · • structural remains of the Toll Gatherer's residence and I associated outbuilding. The domestic quarters and outbuilding such as supply sheds were integral components of the Francis Gate Complex during its years of operation making it more of I a true complex of buildings than it is today. B. Known Subsurface Feature

I 1. An 18' portion of the west bank retaining wall exists at grade at the end of the parking lot for the Francis Gate Complex. This wall extends westerly below the recent graded fill and I probably extends within close proximity of the Toll Gatherer's residence. I II. Swamp Locks A. Potential Subsurface Features

I 1 •. The stone lined sidewalls of the original 1822-23 upper lock chamber may exist directly behind the present 12' wide lock chamber which was I narrowed from 24' in 1892. 2. Portions of the 1841 rubble dam lie covered by the concrete apron which was placed here in 1945 after a washout damaged much of the nineteenth century dam and apron. • 3. 1822-23 southern wing wall. A small section of the southern wing wall which originally extended to the head of the Hamilton Canal I may exist directly adjacent to the southern heel post at the head of the upper lock chamber.

4. Quoin Buttressing. Some form of buttressing or other means of I support may exist behind each of the six hollow quoins of the gate posts.

I B. Known Archeological Features

1. Foundation of the Tool/Watch House. Hidden in the brush to the I east of the "wide gate" house are the brick footing blocks and an 18' long timber which served as the former foundation of the Tool/Watch House which had existed at this location from 1852-1927.

I 2. Saco-Lowell Shops Annealing House. Several partially exposed concrete foundations exist just within (west) the chain link fence which marks the Swamp Locks site as owned by the Proprietors of I Locks and Canals and the Pellon Corporation property. ~ I

I 52 I

III. A. Potential Archeological Features • 1. South Wing Wall. Wooden pilings of the 1841 southern wing wall I may exist adjacent to the fore chamber of the upper lock. 2. North Wing Wall. Fabric from the northern wing wall built in 1845 and altered in 1861 may exist adjacent to the north end of the I Lower Locks dam.

3. Quoin Buttressing. Some form of buttressing may exist behind each I of the six hollow quoins of the locking gates. 4. The lower portion of the 25' wide chamber of the lower lock built in 1822-23 may exist behind the 12' wide portion of the lower I chamber wall which .was narrowed in 1841.

5. The embankment on the south side of the lock which extends from the I tail bay to the Concord River may have been faced with stone or terraces to prevent bank erosion. This feature may lie buried below I debris which is strewn across the entire bank. Although there exist numerous historic references concerning the construction I of canals in general as well as the personal records of Chief Engineer James Francis, our knowledge is by no means complete. Archeology may be necessary to conclusively

document the specific construction techniques and physical detail of the varioua • below-grade elements of canal and lock chamber walls, dams, and former structures I which exist or formerly existed at the Francis Gate Complex, Swamp Locks, and I Lower Locks. Site development at any of these sites may potentially impact cultural resources which represent the crowning achievement of America's foremost early civil I engineer, James Francis, and the canal system which was an integral part of Lowell's I industrial and technological development. I I ~ I

I 53 .)I I I I I I I I APPENDIX I • Outlines of Chronological Development I I I I I I ~ I

I 54 I

NORTHERN CANAL GATE COMPLEX •I Outline of Chronological Development A. Pawtucket Falls Bridge

1792 Middlesex Merrimack River Bridge, the first toll bridge, was I constructed across the Merrimack from School Street in Falls Village to Mammoth Road in West Dracut. (Booth 1980:192-193). I 1803 Middlesex Merrimack River Bridge stone abutments rebuilt (Booth 1980:193). I 1832 Southern portion of Middlesex Merrimack River Bridge rebuilt (Booth 1980:216).

1833 Legislation approves changing bridge name from Middlesex Merrimack I River Bridge to Pawtucket Bridge (Booth 1980:216). I 1838 Northern portion of Pawtucket Bridge rebuilt (Booth 1980:216). 1846-1847 Construction of the Northern Canal and its guard gates and lock required modifications to the Pawtucket Bridge; while the northern end of the bridge remained unaltered, the southern abutment was I moved 60' south of its former location. This portion of the bridge was rebuilt with abutments of coursed granite blocks and a wooden superstructure topped with a simple post-and-rail fence. The roadway of the bridge was 18' wide with a 5' sidewalk on the Gatehouse side and a 5' 6" sidewalk on the downstream side • (Booth 1980:216-222). I 1861 The Pawtucket Bridge was sold to Middlesex County making it a public way.

I 1871 The entire Pawtucket Bridge rebuilt with two abutments instead of three and a cast iron superstructure replacing the 1846-47 wooden arc. The bridge was widened by 11-1/2' flanked by 6' sidewalks I withal' 8" drain between the sidewalks and road. The widening of the approach over the guard gates and lock was accomplished by constructing five brick arches over the ten waste gates. These I were faced with granite and with coal tar concrete sidewalks (Fig. 215). A visible line in the brick work of the vaulted arch indicates the width the original 1846-47 gates and bridge and that which was altered in 1871 (Booth 1980:251-261 for details I and specifications).

1916-1917 Pawtucket Bridge rebuilt in concrete. The 1871 granite and cast I iron bridge was replaced by the present concrete structure. The bridge was designed with a 59' 4" wide roadway; the present bridge is approximately 20' wider than the 1871 bridge it replaced. The road surface was also raised 2 1 partially obscuring the eastern ~ elevation of the gatehouse (Booth 1980:272). I SS I

1960s The superstructure of the Pawtucket Bridge was partially rebuilt ~ by replacing the concrete railings with those made of steel (Booth 1980:272).

I B. Pawtucket Falls Dam

1816 Luke Bowers and his son(s) had built a saw mill and a grist mill I just below the Pawtucket Bridge at School Street. A small wing dam was built to assist in the milling operations (Booth 1980:193). I 1824 Kirk Boott bought the former Bowers' Mills from Thomas Hurd who had purchased it for speculative purposes. Boott then built a temporary wing dam at the Pawtucket Falls to help maintain a sufficient head of water in the newly enlarged Pawtucket Canal I (Booth 1980:194).

1825-1830 A new dam was built by the Proprietors of Locks and Canals which I extended across the entire river at the falls, replacing the 1824 temporary structure (Booth 1980:194).

This dam was built with wooden cribs filled with rubble and provides I a head of 30'.

1833 The Pawtucket Dam was raised 2' with the addition of two courses of I granite blocks. This structure was highly suspectible to freshets, as the original stonework was laid dry, and the stone filling washed out in every flood, requiring recurrent maintenance (Shepley Bulfinch , Industrial:Lowell Canal System:3). 1847 Portions of the southern section of the dam were rebuilt to channel the water into the new gatehouse which was also erected in 1847 on the I southern abutment of the Pawtucket Falls Bridge. Brimstone, a sulfur based material, was used for painting because it was considered to I be more durable than cement (Booth 1980:246). 1875 Proprietors of Locks and Canals rebuilt the segment of the Pawtucket Dam which extends from the Great Rock near the middle of the river to I the Dracut shore (Booth:265). The Guard Gate complex was not altered by this work. (Shepley Bulfinch; Industrial: Lowell Canal System:20, for details of this I project). 1915-1916 The granite and iron bridge built in 1871 was replaced by the larger concrete bridge which exists today. As with the 1871 bridge con~ I struction, no direct reference is made of dam alterations during the 1915-16 building campaign. However, enlargement of the abut­ ments would, at the very least, have necessitated some degree of I modification at the joints between the dam and the Guard Gate Complex. ~ I

I 56 I

c. Northern Canal Gates, Gatehouse, and Lock • 1846-1847 Guard dam, ten sluice gates, boat lock, and gatehouse constructed at head of Northern Canal and adjacent I Pawtucket Falls Dam (Booth 1980:234-248; Robbins).

1854 A portion of the sidewall near the lower end of the lock I was in state of collapse and was rebuilt (Booth 1980:251). 1866 An inclined boat ramp was built next to the Locks and Canals Blacksmith Shop on the Merrimack River. This ramp I served the large f lashboard boat used to make repairs on the dam and is still in existence today (Booth 1980:251).

I 1869 A new back gate was installed at the guard gate hoisting wheel apparently replacing the original 1847 gate (Booth I 1980:251, Robbins 1979:13). 1870 A new water wheel and frame for pumping out the wheel pit was installed (Booth 1980:251).

I 1871 The Pawtucket Bridge rebuilt and widened by about 11-1/2'. This necessitated structural additions to the abutment and approach over the guard gates and lock (Booth 1980:251-261 I and Robbins 1979) . The Northern Canal boat lock closed by taking out the decayed 1847 gates and sealing the upper gate with solid Kyanized timbers of southern pine (Booth 1980.:261 and Figs. 240, 241, • Robbins 1979:14). I 1872 A circular watertight cover of plank and cross timbers placed over the wheel pit to deter flooding and allow maximum I efficiency during freshet (Booth 1980:262, Robbins 1979:14). 1878 A new leather main belt measuring 96" long and 20" wide installed, replacing the original 1848 main belt (Booth 1980: I 264, Robbins 1979:14). 1883 The original cast iron main shaft in the gatehouse was replaced by one which had been forged of wrought iron (Booth 1980:264-265, I Robbins 1979:14).

The small belt pulleys which were a part of the original 1848 I hoisting apparatus were replaced by friction pulleys and clutch mechanisms allowing independent operation of each gate (Booth 1980:265).4 I ''

4. Robbins 1979:14 incorrectly notes that in 1883 the friction pulleys and clutch mechanisms were replaced; it was during this year that they were, It in fact, first installed. I

I 57 I

1891 The hoisting system was electrified by installing three IO-horsepower, 500-volt electric motors in the main shaft. • Although the motors themselves no longer exist, the pulleys I for these first motors are still in place on the line shaft (Booth 265-269).

1891 The metal rack which trapped debris from entering the turbine I chambers was replaced with one made of bronze. This work required the use of a coffer dam which was filtered "into a groove at the bottom, originally cut into the rock • • • I in 1847.'' See Booth 1980:270 for details and sketche~. This groove should exist today in front of the turbine rack. I 1915-1916 Pawtucket Falls Bridge rebuilt in concrete. The bridge that exists today is that which was built in 1915-16 replacing the stone and cast iron structure of 1871. The present bridge is approximately 20' wider than the 1871, necessitating I additions to the downstream arches over the guard gates and lock. The 59' 4" roadway is about 2' higher than the 1871 bridge, partially obscuring the lower portion of the Gatehouse I (Robbins Fig. 14 shows cross section with additions). Screws in the Northern Canal head gates replaced (Booth 1980: I 272). 1923 A single 25-horsepower motor installed in place of the three IO-horsepower motors used since 1891. The 25-horsepower with induction motor with its chain shaft in tact presently hangs from beams at the southern end of the line shaft in the • Gatehouse (Booth 1980:273-276). I 1939 A concrete bulkhead replaced the timber bulkhead installed at the upper gate of the lock when it was closed in 1871.

I 1950s The present remote controlled hoisting system which utilizes ten 5-horsepower motors, one for each gate, replaced the I 1923 motor (Booth 1980:276). Three generations of hoisting apparatus exist:

1. turbine I 2. 1923 25-horsepower engine 3. 1950s ten 5-horsepower using three 10-horsepower. I I ~ I 58 I I

Francis Gate Complex - Outline of Chronological Development • 1796 or A. single wooden navigational lock measuring 100' long by I 1797 25' wide was constructed at the location of the present lock. The original lock chamber's upper gate, when closed, acted as a dam; therefore, it was properly called I a guard lock (Booth 1980:39). 1822-23 The decayed wooden lock was replaced with a single curved chamber built in stone (Fig. ). A second channel was cut I east of the lock, creating an island. The channel was spanned by a guard dam and sluice gates. The gates and dam were con­ structed of wood and were footed on stone sills which were I bolted to the bedrock of the canal bottom. The heavy wooden lock gates were on wooden heel posts.

I Site preparation required the blasting away of 23' of ledge and the erection of a bank wall below the dam and wing walls at the I lower gate of the lock chamber (Booth 1980:39-44). 1825-28 Sometime before March 1828 the Toll Gatherer's residence was built on a lot west of the boat lock. The exact location of this structure though not precisely known, can be inferred from Locks and Canals I drawings (Booth Fig. 16) and a series of maps and atlases of Lowell (Booth Fig. 10, 27, 29) and photographs (Fig. ). (See Booth 1980:44-45 for details.)

1831 A freshet caused water to leak over and around the locks and dam. • A temporary earthen embankment was built at the northerly end of the lock.to check the rising water.

1832 A new guard dam was built on its present location about 23' down­ stream from the 1822-23 dam. Unlike its wooden predecessor, this I structure was built of granite and featured five sluice ways and gates (Booth 1980:Figs. 17, 22). I A five-bay wooden gatehouse was constructed over the guard dam to house the gate hoisting apparatus (Booth 1980:Fig. 16).

The use of explosives for site preparation is att.ested to by the I purchase of powder from the local Whipple Powder Mill. See Booth 1980:46-51 for detail~ on the construction of the 1832 I guard dam and gatehouse. 1838-39 Repairs were made to the boat lock. The .nature or extent of this work is not clear. A ledger entry indicates an expenditure for I stone, suggesting that some masonry work was undertaken at this time.

The 1822-23 wooden heel posts for the locking gates were replaced t. (Booth 1980:55). I

I 59 1842 A Counting Room was constructed, presumably at the northern end of the island adjacent the upper locking gates as shown. in Booth: 1980 Figs. 17, 18, 21, 22, 26. The only reference to this feature, other than maps, is a ledger entry which indicates that the structure was footed on a mortar foundation (Booth 1980:56).

1846(?) By 1846 windlasses had been attached to the gates of the boat lock to facilitate easy movement (Booth 1980:71, Fig. 17).

1847 The eastern gate at the head of the boat lock was fitted with I a large cast iron pintel (Booth 1980:56-57).

1848-50 Fear that the guard dam and lock would not withstand a major I freshet, which would be abnormally high due to obstructions in the Merrimack caused by development of the Northern Canal and Pawtucket Bridge, resulted in raising the height of the I dam and central part of the lock by 6'. Booth Figs. 21 and 22 reveal that the central portion of the locks were straightened to adapt it to the Great Gate which I was also built and hung in 1850.

The central portion of the island was raised by 6' by introducing I considerable quantities of fill (2,000 yards). This area was stabilized by the construction of a granite retaining wall and a below-grade rubble wall angling from the retaining wall diagonally , to the Great Gatehouse. The Great Gate was built and hung in the central section of the lock which had been straightened and provided with large grooves I in the sidewalls for the dropped gate. The present Great Gatehouse was also erected at this time (Booth 1980:57-68). I 1852-Broadway Bridge

1853 A new set of balance levers, made of Burnettized white pine, was I installed at the locking gates (Booth 1980:70). The use of the term "new set" of balance levers is somewhat confusing in that it is not clear as to whether this meant levers attached to all I gates or only to one pair. If the latter--was it the upper or lower gates? I 1856 The upper pair of locking gates and all five of the guard dam's sluice gates were replaced. In both cases the earlier (1832, 1848) hardware was reused and no alterations occurred to the I stonework (Booth 1980:71, 72). I. I I 60 I

1857 .. The western gate of the upper lock was fitted with a cast '9 iron pintle similar to the one attached to the eastern gate in 1847 (Booth 1980:72).

1 The first house to span the upper locking gates was also con­ structed in 1857. A plan shows this structure with the two smaller windlass shelters adjacent either end (Booth 1980: I Fig. 26).

1858 Large timbers were erected in the Great Gatehouse to provide I a track or "guide" for the Great Gate to prevent it from becoming stuck in the stone grooves of the lock walls when dropped (Booth 1980:73).

I 1859 A new 300' boom was "built of four timbers of Burnettized spruce, built upstream from the guard gates" (Booth 1980:73).

I The lower pair of locking gates was replaced with new gates constructed of Burnettized oak and pine. Presumarly, it was I the 1822 gates that were replaced (Booth 1980:74). 1866-67 Considerable site alteration occurred during this period.

Repairs were made to Guard Gatehouse. A truss was built beneath I the sill on the northern side of the structure to retard further slippage .

A second story was added to the Toll Gatherer's House which was • originally built between 1825-20 . Dredging removed considerable quantities of stone and gravel from .1 the bottom of the canal near the Broadway Bridge, and, presumably, blasting aided in removing the ledge on the westerly side of the I canal directly below the guard dam. Based on the written evidence, it is likely that both sidewalls of the canal channel running directly below and extending to the I Broadway Bridge were rebuilt. This would have included the southern end of the island. However, lacking a confirming entry, Booth (1980:77) hesitates to conclude whether, in fact, any walls I were rebuilt during this time. The granite ashlar retaining wall running perpendicularly midway across the island and its extension running westerly from the I lock, built in 1848, were relaid (Booth 1980:76, 77).

A post-and-rail fence was placed on top of the retaining walls I (Booth 1980 Fig. 36, 84). A small section of a post-and-rail fence presently exists on the retaining wall to the west of the lock (Booth 1980:Fig. 93).

I 61 ,-. 1868 The eastern bank of the canal below the Guard Gates was I sodded (Booth 1980:78). The 1857 boom was reinforced with additional timber bracing and new fastenings were attached to the lower end (Booth 'I 1980:78). 1870 Due to excessive leakage, the guard gates and sluices were rebuilt along the lines of those at the Northern Canal Gate­ house. The existing stonework was adapted to the new gates, and considerable painting and grouting on the downstream side of the dam occurred. Booth (1980:83-86) provided an in-depth discussion of this work.

The old hoisting apparatus was sold and five hydraulic-assisted lifts put in their place to operate the new gates. A 6" pipe 'I running from an existing pipe in Mechanics Street to Broadway and to the gatehouse, a distance of 3,858', provided water for I the new hoisting apparatus. The existing Guard Gatehouse was also built at this time (Booth ·1 1980:87-92 and Robbins __). 1871 The eastern sidewalls of the canal between the guard gate and Broadway were in need of repair because of the turbulence caused by the wasting water through the sluices. This replaced the wall built in 1867. The east bank was graded between the guard gates • and Broadway. Beautification at the site included the planting of 26 elm trees on the eastern bank near Broadway and 12 horse chestnut trees on the westerly bank above the lock chamber (Booth 1980:92).

I 1872 The roofs of the office, windlass houses, house over the upper lock gates and the southerly side of the Great Gatehouse were reshingled. The office is probably depicted in Locks and Canals drawings of 1836, 1846, 1855, and 1870 (Booth Figs. 14b, 17, 18, 22, 23) which show a small rectangular structure at the northern I end of the entrance adjacent the upper locking gates. 1876 The Great Gate was strengthened by adding strategically placed timber (Booth 1980:94-95).

I 1877 The lock chamber walls between the Great Gatehouse and the lower gates were rebuilt and straightened. Most of the hollow quoins required resetting as well. Portland cement was used on the I hollow quoins and all the below-water-level sections of the new sidewalls. The upper portions were laid with a mixture of "Lime and Newmark Lime and Cement Co. cement."

A portion of the masonry for the Great Gatehouse originally laid ~ dry was grouted with a mixture of lime and American cement (Booth I 1980:99). I 62 I la A water hydrant was placed somewhere in the vicinity of the Guard Gatehouse with a water line connected to a city I hydrant which existed on the "northerly side of Broadway . · about 40' easterly of the L./C. hydrant." A brick shelter I· was built around the new hydrant (Booth 1980:100). 1881 An extensive program of site alteration was undertaken in 1881.

The round lock walls extending from the Great Gate to the upper I locking gates were straightened.

The entire northern end of the island was reshaped by decreasing I its size considerably and adding new granite walls on its edges. The shape of the northern end of the island is the result of this project. Booth, Fig. 30, indicates the extent to which the shape changes as well as indicating the former curved lock walls I juxtaposed with the new straightened walls.

The ashlar retaining wall, built in 1848 when the island was I raised 6', (Booth Fig. 26) was moved back several feet assuming the straight configuration which it exhibits today (Booth Fig. 30). I The present Italianate Lock House replaced the former Lock House and adjacent windlass houses at the upper locking gates. New windlasses were also installed, replacing those in place prior to 1846.

The office, which first appeared in an 1836 plan (Booth Fig. 146), located at the northern end of the island was removed from the I island probably because of the reduction in surface area. The upper locking gates, presumably those installed in 1856, were replaced, and the mitre sill was grouted with melted sulfur to I prevent leakage. (See Booth 1980:i09 for a discussion of this grouting process.)

I A confusing entry by Francis is an expenditure to the diver for "taking up old wall and removing coffer dam." Booth (1980:110) suggests that perhaps the "old wall" refers to the wall which I faced the northern side of the island. This work took place between October 30 - November 11th, only about two weeks before the entire project was completed. It is possible, though I think unlikely, that the island would have been extensively I reshaped, removing quantities of soil and laying a new wall within the former wall. Not only would this have constricted the working space but there was no need to maintain the old I wall temporarily with a coffer dam in place.

I 63 An alternative interpretation is that the "old wall" referred to the sill of the 1822-23 guard gate, reused in 1832, 1846, • and 1870 during site work. By 1881 this sill may have been I sufficiently deteriorated to be no longer functional, as such, it represented an obstacle to the flow of water above the guard gates. The problem with this interpretation is I that the feature has always been referred to as the old 1821-12 dam sill and never termed the "old wall."

1882 Ten pintles of the new upper locking gates failed and were I replaced by ones manufactured in wrought iron. The original 1822 pintels were wrought iron and were replaced in 1847-57 by ones of cast iron which at the time they must have felt I were a better material for such an element.

1885 Among a series of minor maintenance projects this year is an I entry to "Paint the new stone house for the water pipe." (Booth 1980:112). In 1877 a brick structure was built around a new water hydrant at the Guard Gatehouse. Had the brick structure been replaced by a new wooden structure in need of I paint or it this yet another structure which was associated with the complex?

I' 1893-95 Extensive dredging operations enlarged, straightened, and deepened the canal above the headgates, thereby increasing the working capacity of the canal. The spoil was deposited in the eastern shore and between Broadway and Pawtucket Streets, and walls were built on both sides of the canal, improving a • considerable area which was then publicly sold (Booth 1980: I 113-114). 1895- A drain (ditch) measuring an additional 5' below the bottom of 1902 the canal was excavated between the Francis gate complex and I Swamp Locks.

1900 The ~estern walls of the canal below the guard gates was straightened and rebuilt. Booth, Figs. 41, 42, 43, 44 indicates I the nature and extent to which the southern end of the island was rebuilt (Booth 1900:115).

I 1902 The headgate sluices were enlarged by adding an inclined plank flooring to each sluice. The wooden extensions no longer exist though some of the cement covering which protected them is in I place (Booth 1980:115). 1902-07 The drain must not have increased the water flow as much as desired because during this period the ledge below the guard I gates was blasted away to a depth of 4' equally that of the drain. Canal walls were built and spoil backfilled between them, and much improved land was sold (Booth 1980:116). It 1924 The left hand upper locking gate was rebuilt (Booth 1980 Fig. 62). I I 64 I

1942 Guard Gatehouse sill repaired (Booth 1980:Fig. 80, 81).

• Three of the original hydraulic hoisting cylinders were 1965 I replaced with new oil hydraulic pumping cylinders. The two original 1870 cylinders exist at either end of the row of I hoisting apparatus (Booth 1980:1965). 1970s A metal bulkhead was placed in the grooves just above the I Great Gate (Booth 1980:121). I I I I • I I I I I I ~ 1·

I 65 I • Swamp Locks - Outline of Chronological Development 1792- The first navigational lock built here was a single wooden I 1796 chamber measuring 150' long by 32' wide. During the opening day ceremony for the Pawtucket Canal, the wooden lock chamber at Swamp Locks burst, requiring a second wooden chamber ·to be I constructed before the facility became operational (Booth 1980:122-23). I 1800 An earthen dam or dike was erected over the low ground above the lock (Booth 1980:123) Hale's 1821 "Plan of .•. Pawtucket in the Town of Chelmsford" (Booth 1980:Fig. 7) shows a narrow. earthen ridge angling in a northeasterly direction off the I north side of the basin. This dike would encourage pondage and reduce water seepage into the low lying areas around the I lock when its gates were closed. 1822-23 Swamp Locks and dam rebuilt. An extensive development program was undertaken in conjunction with the transformation of the I Pawtucket Canal into a power canal. A new 13' high stone dam with regulating gates was built. To acconunodate the increased drop created by the higher dam an I additional lock, the upper lock, was constructed in stone, with a 25' width. The original lock, th~ lower lock, was also rebuilt in stone and narrowed from 32' to 25'. An 1824 map (Fig. 8, Booth 1980) is the first representation of the site after the 1822-23 building, and shows the general configuration • which is retained today. I The chambers were lined with wood planks to make them watertight.

The narrow island separating the locks from the dam and the I waterway was faced with a substantial rubble wall.

The Merrimack Canal flowing off the basin just above (north) I of the dam was also excavated at this time transforming the Swamp Locks basin into the dividing line between the upper and lower Pawtucket Canal and making it the logistical center I of the entire canal system (Booth 1980:123-126). 1832- A portion of the main track of the Boston and Lowell railroad 1835 was built across the Swamp Locks basin (Booth 1980:128). I (Today this is part of the Boston and Maine Railroad Corporation.) Swamp Locks narrowed by constructing "wooden frames against, and a few feet out from the stone chamber wall" put in in 1822, thus I creating a chamber within a chamber. The new 12' wide chambers were then lined with pine planks so they would hold water. Ashlar masonry was used to narrow the walls around the gate heel posts. Though an original proposal called for some metric sills, pine ~ sills were used until 1864 (Booth 1980:130-131). I

I 66 I

1841 The Swamp Locks dam was rebuilt using 2,490 cubic feet of granite, assuming the multi-leveled, or stepped configuration which it • retains today. The deep gate and sluiceway in the south part of I the dam, and the frame structure which stands over the deep gate, but not including the building over the hoisting apparatus, were probably also built at this time (Booth 1980:131).

I Extensive wall building and repair was undertaken in 1854. A wall was constructed at the north end of the dam connecting the dam with I the wing wall of the Merrimack Canal (Booth 1980, Fig. 116). The wall was constructed of conrete measuring 1/2'· in thickness and approximately 11' deep where it was footed on the natural ledge and I puddled with gravel. A second wall, the rubble wall on the north side of the island between the dam and the locks, was also repaired in 1854. The clay puddle was I excavated from behind this wall which was replaced by a 2' thick cement backing. Additionally, three or four of the top courses were reset I with a solid cement backing (Boo.th 1980: 132). The third wall section receiving attention was the wing wall (piling) on the south side of the Swamp Locks Basin, extending from the head­ I gate of the upper lock to the Hamilton C~nal. Francis' description of the work is not entirely clear. It appears that some sections of this wall, originally built in wood and stone masonry, were backed with a 3' thick wall of cement (Booth 1980:133). • 1858 Piles were driven into the ledge to provide support for the boom which extended from near the north end of the dam across the head of the I Merrimack Canal. The boom defined the portion of the Pawtucket Canal in the basin, to which the public had access to as a navigational canal, from the Merrimack Canal which was solely a power canal (Booth I 1980:133). 1859 The south wing wall repaired in 1854 was again in need of work. The puddling on either side of the wall was excavated to a depth I of 6' and 'the top of the wall was rebuilt. The sloping walls were then plastered smooth with cement (Newark Company cement: 2 parts I sand, 1 part cement) (Booth 1980:134). The wood work of the superstructure dams was completely renewed in 1859. New timbers, planking, flashboard irons, stone and mortar I waste gates and caps were all installed. The narrow frame house was built near the entire crest of the dam. The earlier (1841) two bay, pitcher roof gatehouse over the deep· I gate was incorporated into this new feature. (Booth 1980, Figs. 116, 117, 125, 150, and 148) (also see Booth 1980:134-136 for a detailed description of these buildings.)

The wooden inner chambers installed in 1840 to narrow the locks I. were replaced, maintaining the narrow 12' chamber (Booth 1980:139-140). I

I 67 I

1865 All three pair of locking gates installed in 1840 were replaced with ones made of Kyanized Northern white pine (Booth 1980:140).

• 1868 New booms were built in the basin above the locks and dam. The I booms measuring about 685' in length were constructed of sub­ stantial spruce 12" by 12" timber about a ton of Norway iron I was used for straps, bands, and other functions (Booth 1980:141). 1871 New balance levers were fastened to the upper set of gates I (Booth 1980:141). 1874 Tratch House and/or Tool House moved and repaired. Records do not conclusively indicate when such a structure first appeared on the site or from where it was moved, though a structure does appear I on the island as early as 1852 (Booth 1980:Fig. 100), records do not conclusively indicate when such a structure first appeared on the I site or from where it was moved (see below). 1885 Plans were made to repair the lower lock chamber. The estimate included a comparison between the cost of wood and that of stone, I (Booth 1980:144-146). If the work was undertaken, the wooden chamber was rebuilt and was never renewed after it had finally deteriorated for the lower lock I chamber that exists today is the original 25' wide chamber built in 1822-23 .

1892 The upper lock chamber was permanently narrowed with quarried stone • to a width of 12'. (Booth 1980:Fig. 105) the entire cross section was completed, I revealing that the new ashlar wall is 4' wide at the bottom and 3' wide at the top was constructed inside the 1822 wall. The I space between the two walls was filled with rubble (Booth 1980:147). Three pairs of locking gates made of spruce replaced the white pine I gates hanging since 1865 (Booth 1980:148-149). 1894- Major renovations transformed the swamp basin. 1895 A .new granite wall running from the head of the upper gates to the I Hamilton Canal was constructed at points as much as 38' from the original wing walls repaired in 1854 and 1859. Approximately 1/2 acre of land was reclaimed with landfill, transforming the config­ I uration. Figure 139a shows how the basin looked after the filling and walls were built. A dotted line from the locks across the Lowell Machine Shop property, also indicates the pre- and post-1894-95 I land form conditions. It I . \

I 68 I

A granite and wood ramp was built into a part of the south wing wall, beginning at a point approximately 45' upstream • from the head gate of the upper lock. The 1890s was a period I during which most of the walls for the entire canal system were finally all rebuilt in stone and straightened to their present configuration. These ramps provided the only easy means of deploying men and teams to the canals for periodic I repairs and cleaning once all the walls were completed (Booth I 1980:149-150). I I I I

I• I

I ~ I I I ~ I I 69 I

Lower Locks - Outline of Chronological Development •I 1792-96 Two wooden lock chambers each 150' long and 32' wide constructed during this period. Problems with the water level of the Concord required that 100' of the lower lock I be taken up and reset 3' deeper (Booth 1980:159; 15-16).

1802(?) Possibly as early as 1802 a third lock chamber existed at the I site. No details exist but this configuration appears in J. G. Hale's map Pawtucket Farms 1821 (Booth 1980:159; 16-17, Figs. 7 and 153).

I 1823-24 Lower Locks rebuilt and first dam constructed. Two stone lined chambers replaced the three wooden chambers the timbers of which were physically removed from the site (Booth 1980:164). Excavations I to a depth of 40' were undertaken for the lock pits (Booth 1980:166). The side walls were constructed of large and small stone laid with­ out mortar. The chambers were 25' wide and lined with lumber in I order to hold water (Booth 1980:167). Details of the first dam are lacking, but an account entry was made for the building of sluice gates (Booth 1980:104) and mention of I "filling in at the Dam, Lower Locks" and" .•• levelling off back of dam .••• " (Booth 1980:165) suggests that the dam may have been earthen or partially earthen with a rubble core with sluice gates get into it • • The rubble stonework of the wasteway wall and lock chamber walls .1 are remnants of this development. 1841 Lock chambers narrowed to 12' by constructing a chamber with a chamber made of bracing timbers and planking. The lock gates I were permanently narrowed to 12' with granite ashlar masonry set with hydraulic cement (Booth 1980:171-172). I The lower portion of the lower chamber was rebuilt in ashlar (Booth 1980:172).

Excavations removed 37. 44 perches of cobble and. the wall on the I north side of the race to the Lower Locks dam constructed. The dam was partially reconstructed and new paving above and below the dam spiling set in place. Ledger indicates "Old side wall I near dam" removed "McAdamizing stone. • • used under flooring of lower chambers" (Booth 1980:175). The pitched roof, clap­ boarded gatehouse over the dam, and the large sluice gate near I the northern end of the Lowe Locks dam may be aspects of this extensive 1841 rebuilding program.

1852 Experiments on the flow of water over the weirs made by Francis and James F. Baldwin required some temporary modifications to ~ the locks including the removal of the upper set of lock gates I and their mitre sills (Booth 1980:178).

I 70 1860 The wooden inner chambers in place for 19 years were completely replaced with new Burnettized side planking and timbers (Booth • 1980:178). I Also replaced the wooden piling on the south side of the headgates (the wing wall at the southern end of the dam which also serves as the upper wing wall and forebay of the upper lock). The wooden I pilings taken up only to a depth of 7' 8" and a 2' thick stone wall was built about "one foot below the top of the southern pine plank piling" (Booth 1980:179) suggesting that the lowest portions I of these pilings may exist below the stone wall. 1861 The wing piling (wall) at the northerly end of dam repaired by constructing a stone wall laid in New York cement (Booth 1980:179, I Sketch 180). I The paving at the foot of the dam was also repaired in 1861. 1865 Repairs were undertaken to the gatehouse over the dam to a "watch or tool house'' to the northeast of the dam (Booth 1980:182).

This is the first mention of a Tool House which was moved from the site sometime between 1879 and 1896. This location is presently I part of a paved parking lot. A second small house appears at the head of the island between the ,, upper lock and the dam (Booth Figs. 159, 169, 171, 172, 173, 178). No information exists concerning when it was built, though stylistically is resembles 1840s. The house may have been a Tool House/office for the locking system. .~I 1865 The three pairs of locking gates were replaced with new gates made of Kyanized Northern white pine (Booth 1980:183).· ~I 1871 New Kyanized balance levers attached to the upper set of locking gates (Booth 1980:184).

1874 Decayed "plank piling" located at the "southerly end of the wasteway of the Lower locks dam" was repaired. There exists some confusion as to exactly where at the Lower Locks this refers to.

1876 The woodwork in both chambers was rebuilt with Kyanized spruce. The spruce and floor timbers of the upper chamber were not renewed (Booth 1980:184-185).

1876 Apron of the dam replanked.

1877 Current meter experiments required well-jointed sills. The spaces between the sills of the sides of the locks and footing stones pointed with Portlant cement on the front and grouted from the 't. lock with American cement. I

I 71 I

'9 1878 Again experiments required some masonry work, but the records do not specifically indicate what or where this was done 1 (Booth 1980:187). 1887 New sluiceways and waste gate at the Lower Locks dam were con­ structed replacing those built in 1841 (Booth 1980:187-188, I Fig. 160).

1892 February 1892 a schedule for lumber was drawn up by Francis for I the replacement of the gates which had hung since 1865 (Booth 1980:189).

1900 A 1900 sketch of the upper gates and the Lower Locks suggests I that perhaps these gates or at least the upper gates were not actually renewed until this time (Booth 1980:Fig. 161).

I 1905 In order to maintain water in the Lower Lock during low water conditions in the Concord, the eastern half of the lock was I deepened by approximately 2-1/2' (Fig.~->· 1910 A 24" drainage pipe was laid from a main valve on the small island above the dam, extending beneath the upper lock and emptying into the Lower Lock. The pipe, which is operational I today, serves to drain the lower Pawtucket Canal and appears in the HAER drawings (Fig.~->·

1946-58 Three concrete siphon spillways were built on the downstream, eastern side of the dam between 1946-58. Figure 177, Booth • 1980, shows the plans and sections of these spillways (see I also Booth 1980 Figs. 178, 186a). I I

I I

72 I

'9 BIBLIOGRAPHY Baker, I. o.

1 1889 Treatise on Masonry Construction, John Willey & Sons, New York. I Booth, A. 1980 Historic Structures Report. Historical Data. Pawtucket Canal Guard Gates, Boat Lock, Great Gate; Northern Canal Guard Gates I and Boat Lock; Swamp Locks; Lower Locks, National Park Service, Denver, Colorado. I Burton, A. 1972 The Canal Builders. Eyre Methuen, London.

Cqwley, C.

1868 Illustrated History of Lowell. Sargent and Merrill, Lowell, I Massachusetts. Cresy, E.

I 1847 An Encyclopedia of Civil Engineering, Historical, Theoretical and Practical. Vol. II. Longman, Brown, Green and Longmans, London. • Gibb, G. S. 1950 The Saco-Lowell Shops 1813-1949. Harvard University Press, I Cambridge, Maryland. I Hudson, K. 1976 The Archaeology of Industry. Charles Scribners Sons, New York. I Lankton, L. D. and P. M. Malone 1973 The Power Canals of Lowell, Massachusetts. Occasional Paper, Lowell Urban National Park Project. Human Service Corporation, I Lowell, Massachusetts. I Mahan, D. H. 1856 An Elementary Course of Civil Engineering. Willey and Halstead, I New York. McKee, H. J.

1973 Introduction to Early American Masonry, Stone, Brick, Mortar, Plaster. National Trust for Historic Preservation and Columbia ~ University. I

I 73 I '9 Miniken, R. C. 1920 Practical River and Canal Engineering. Griffin & Col, Ltd., 1 London. Pannel, J. P. M. I 1964 An Illustrated History of Civil Engineering. Ungar Publishing Company, New York. I Patton, W. M~ 1895 A Treatise on Civil Engineering: Willey & Sons, New York.

I Robbins J. and A. 'Guitian

1980 Historic Structures Report. Architectural Data. Pawtucket Canal I Guard Gates, Lock and Great Gate and Northern Canal Guard Gates and Lock·. National Park Service, Denver, Colorado. I Rosebrock, E. 1980 Lowell Heritage State Park: Transportation System. (B-1 Draft) Institute of Conservation Archeology, Peabody Museum, \Cambridge, I Maryland .

Shepley, Bulfinch, Richardson and Abbott

1980 Report Lowell National Historical Park and Preservation District • Cultural Resources Inventory. I Vernon, L. F ~ I 1882 A Treatise on Rivers and Canals. Harcourt Clarendon Press, Oxford. I I I I \ I

I 74 I

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I /~25 ""'9'9 I

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~ Fig. 26 . I Lower chamber at Lower Locks after the "Inverted Arch" bottom completed in 1905. I 100 .- ··- I I

Fig. 27 . Dredging activities in progress in 1905 below the lower chamber of the Lower Locks .

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101