heritage

Article Conservation of the Traditional Grain Mills in , : Study of Mechanical Systems and Restoration

Yasser Ali

Head Restoration for Islamic and Coptic Antiquities, Ministry of Antiquities, Dakhla Oasis 72719, Egypt; [email protected]; Tel.: +20-0101-1671-845

 Received: 11 September 2018; Accepted: 10 October 2018; Published: 17 October 2018 

Abstract: This paper is the first study of traditional grain mills in Dakhla Oasis, Egypt, to ensure the sustainability of these traditional production systems while retaining their original function. In this sense, the aim of this study was to analyze the mechanical systems of the animal-powered traditional mills in Dakhla Oasis, which remain the key to figuring out the puzzle of how these mills work and produce flour. This is an original study that examines a sample animal-powered mill to be conserved; this sample old mill was selected from seven potential grain mills, after investigating each mill. This study provides the technical background and description of the selected grain mill in Dakhla Oasis, and describes its working and mechanical movement. In addition, the physical properties of the historic grain mill wood were measured (e.g., density, shrinkage, and hardness), using scientific techniques, to get some information about their properties. In this study, the methodology for grain mill conservation was based on a combination of the traditional experience of the old craftsmen and modern technology applications in the restoration and rehabilitation of animal-powered mills, in addition to the use of software programs in data analysis. Our results proved that the ancient traditional expertise of the old craftsmen and scientific techniques are the most appropriate methods for restoring and preserving animal-powered mills, which include the determination and rework of the mechanical movement between the wooden gear wheel and millstones. Finally, this study gives an in-depth look into the practical scientific restoration of animal-powered mills in Egypt and other countries.

Keywords: Dakhla Oasis; grain mills; mechanical systems; animal-powered; traditional expertise

1. Introduction The milling of grain has been done since the dawn of history. Grinding was mostly women’s work and only the amount of meal needed each day was prepared. They fought tedium by singing chants such as “May the gods give my master strength and health” [1]. The history of the ancient grain mills in Dakhla Oasis is closely related to that of the bread industry. Wheat, barley, corn, and other grains have been milled there for the purpose of baking; they are the main source of food in Dakhla Oasis, as it is a purely agricultural environment. Egyptian oases house various known milling machines, including the primitive form and the grain mill. The grain mill is based on the mechanical movement between a wooden gear and millstones and is animal-powered. Dakhla Oasis lies in the in Egypt, 950 km from , and between the oases of Farafra and Kharga, as seen in Figure1. There are several cultural heritage sites made of mud brick in Dakhla Oasis, such as Al-Qasr [2], as well as charming mud-brick housing in the fortified town and the city of Balat. Moreover, there are seven similar animal-powered historical mills in Dakhla Oasis that we need to know about, and what to do with each one.

Heritage 2018, 1, 254–272; doi:10.3390/heritage1020017 www.mdpi.com/journal/heritage Heritage 2018, 1 255 Heritage 2018, 2, x FOR PEER REVIEW 2 of 18

Figure 1. MapMap of of Egypt Egypt which which shows shows Dakhla Dakhla Oasis: Oasis: Loca Locatedted 189 189 km km west west of Kharga of , Oasis, Egypt Egypt (by (byauthor). author).

Historical Background of Grain Mills in Egypt Historical Background of Grain Mills in Egypt Grain mills in Egypt, and the old towns in which they sit, have long been a part of Egyptian Grain mills in Egypt, and the old towns in which they sit, have long been a part of Egyptian heritage. However, the mill which was found in the archaeological area of al-Tarqah, in , heritage. However, the mill which was found in the archaeological area of al-Tarqah, in Upper Egypt, and used in grain milling for more than three thousand years, is one of the oldest and most famous and used in grain milling for more than three thousand years, is one of the oldest and most famous mills. The length is 48 cm, and there is a gap at the top, which is used to grind the grain. There are a mills. The length is 48 cm, and there is a gap at the top, which is used to grind the grain. There are a few animal-powered mills used to grind grain, including the Abu Shahin mill, which was established few animal-powered mills used to grind grain, including the Abu Shahin mill, which was established by Osman Agha al-Tobji in the twelfth century AH, in Rashid City, north of Cairo, in addition to by Osman Agha al-Tobji in the twelfth century AH, in Rashid City, north of Cairo, in addition to animal-powered mills in Dakhla Oasis. animal-powered mills in Dakhla Oasis.. Grinding grain into flour began early in mud-brick houses in Dakhla Oasis, Egypt, whereby Grinding grain into flour began early in mud-brick houses in Dakhla Oasis, Egypt, whereby women used a stone bowl (mortar) made of a native palm trunk and a long stone (pestle) made of women used a stone bowl (mortar) made of a native palm trunk and a long stone (pestle) made of acacia wood to make flour for bread, as those shown in Figure 2. acacia wood to make flour for bread, as those shown in Figure2. Then began the use of the handmill (see Figure3). The handmill is one of the most primitive utensils found in the world. As we have learnt from wooden models found in Egyptian tombs, now preserved in the Museum of Gizeh in Egypt, the way these utensils worked was by placing one round flat stone on another stone of the same kind using the power of the human hand—that is to say, the handmill [3]. Luckily, there are still a few of the old hand-powered mills for grinding grain available in Dakhla Oasis. Made during the Mamaluke and Turkish eras, this mill generally consisted of a couple of hard stones, the upper stone convex from the sides, 98 cm diameter, 20 cm thickness with a 11 cm hole in the center, and a lower fixed stone with a wooden peg at the center (see Figure4).

Figure 2. Ancient mortar and pestle.

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Figure 1. Map of Egypt which shows Dakhla Oasis: Located 189 km west of Kharga Oasis, Egypt (by author).

Historical Background of Grain Mills in Egypt Grain mills in Egypt, and the old towns in which they sit, have long been a part of Egyptian heritage. However, the mill which was found in the archaeological area of al-Tarqah, in Upper Egypt, and used in grain milling for more than three thousand years, is one of the oldest and most famous mills. The length is 48 cm, and there is a gap at the top, which is used to grind the grain. There are a few animal-powered mills used to grind grain, including the Abu Shahin mill, which was established by Osman Agha al-Tobji in the twelfth century AH, in Rashid City, north of Cairo, in addition to animal-powered mills in Dakhla Oasis. Grinding grain into flour began early in mud-brick houses in Dakhla Oasis, Egypt, whereby women used a stone bowl (mortar) made of a native palm trunk and a long stone (pestle) made of Heritage 2018, 1 256 acacia wood to make flour for bread, as those shown in Figure 2.

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Then began the use of the handmill (see Figure 3). The handmill is one of the most primitive utensils found in the world. As we have learnt from wooden models found in Egyptian tombs, now preserved in the Museum of Gizeh in Egypt, the way these utensils worked was by placing one round flat stone on another stone of the same kind using the power of the human hand—that is to say, the handmill [3]. Luckily, there are still a few of the old hand-powered mills for grinding grain available in Dakhla Oasis. Made during the Mamaluke and Turkish eras, this mill generally consisted of a couple of hard stones, the upper stone convex from the sides, 98 cm diameter, 20 cm thickness with a 11cm hole in the center, and a lowerFigureFigure fixed 2. Ancient 2. stoneAncient withmortar a and andwooden pestle. pestle. peg at the center (see Figure 4).

Figure 3. ShowingFigure 3. whatShowing a handmill what a handmill is and is and how how it it could could be be used used in making in making flour. (Aliaflour. Hussein (Alia 1965). Hussein 1965). (DH/Alia Hussein,(DH/Alia 1965) Hussein, [4]. 1965) [4].

Figure 4. Old handmill in Dakhla Oasis.

A mechanism of the grinding process in Dakhla Oasis has evolved into the type of animal- powered mill since the Ottoman era. Consequently, the Abu Ishmael mill, one of the landmarks of the town of Al-Qasr, was built during the Turkish era in 1198 AH to be used to grind grain for all the people, according to the wooden lintel over the entrance. In addition, we have the Sheikh Ahmed mill (see Figure 5) and El-Prince Mill (Figure 6), which is one of the largest mills in the village of Balat. The millstone in this mill is one of the biggest millstones in Dakhla Oasis, with more than alternatives for a millstone, as seen in Figure 6. It had a presence in the production of flour and was built during the 4th century AH, according to the wooden lintel over the entrance.

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Then began the use of the handmill (see Figure 3). The handmill is one of the most primitive utensils found in the world. As we have learnt from wooden models found in Egyptian tombs, now preserved in the Museum of Gizeh in Egypt, the way these utensils worked was by placing one round flat stone on another stone of the same kind using the power of the human hand—that is to say, the handmill [3]. Luckily, there are still a few of the old hand-powered mills for grinding grain available in Dakhla Oasis. Made during the Mamaluke and Turkish eras, this mill generally consisted of a couple of hard stones, the upper stone convex from the sides, 98 cm diameter, 20 cm thickness with a 11cm hole in the center, and a lower fixed stone with a wooden peg at the center (see Figure 4).

Figure 3. Showing what a handmill is and how it could be used in making flour. (Alia Hussein 1965). Heritage 2018, 1 257 (DH/Alia Hussein, 1965) [4].

FigureFigure 4. 4.OldOld handmill handmill inin Dakhla Dakhla Oasis. Oasis.

A mechanismA mechanism of the of thegrinding grinding process in Dakhlain Dakhla Oasis hasOasis evolved has intoevolved the type into of animal-powered the type of animal- poweredmill mill since since the the Ottoman Ottoman era. Consequently, era. Consequently the Abu, Ishmael the Abu mill, Ishmael one of the mill, landmarks one ofof the the landmarks town of the townof of Al-Qasr, Al-Qasr, was was built built during duri theng Turkish the Turkish era in 1198 era AH in to1198 be used AH toto grind be used grain to for grind all the grain people, for all the people, accordingaccording to to the the wooden wooden lintel lintel over over the entrance.the entrance. In addition, In addition, we have we the have Sheikh the Sheikh Ahmed Ahmed mill mill (see Figure5) and El-Prince Mill (Figure6), which is one of the largest mills in the village of Balat. (see FigureThe 5) millstone and El-Prince in this mill Mill is one (Figure of the 6), biggest which millstones is one inof Dakhla the largest Oasis, mills with more in the than village alternatives of Balat. The millstonefor in a this millstone, mill is as one seen of in Figurethe biggest6. It had millstones a presence inin theDakhla production Oasis, of flourwith andmore was than built alternatives during for a millstone,theHeritage 4th as 2018 centuryseen, 2, xin FOR AH, Figure PEER according REVIEW 6. It hadto the a wooden presence lintel in over the theproduction entrance. of flour and was built4 of during 18 the 4th century AH, according to the wooden lintel over the entrance.

Figure 5. (a) Abu Ishmael mill. ( b) El-Sheikh Ahmed mill.mill.

Figure 6. El-Prince grain mill.

2. Materials and Methodology

2.1. Description and Technical Background The simplest type of animal-powered mill is the gearless stone mill, known in antiquity as the “hourglass mill” [5]. The animal-powered mill in Dakhla Oasis is a machine for converting the energy of animal-powered into useful forms of mechanical movement, usually in a grain mill. A grain mill consists of a wooden gear wheel (Perimeter = 6.20 m; Radius = 95 cm) (usually constructed from acacia wood), with sixty wooden sprockets (Length = 31 cm; Width = 4 cm). The wheel is actually based on a wooden cross and mounted horizontally on a vertical shaft (a drive shaft) (Length = 2.35 m; Width = 27 cm), with a wooden finger at the hole under the center of a large hollow wheel, with its base pivoting on a wooden concave base set in the middle of a stone base. A drive shaft is rotated in a hole inside a “wooden balance” (Length = 91 cm; Width = 0.22 cm) between the drive shaft and the wooden palm trunk which bears all the parts of the mill (Length = 6.10 cm). In the middle of the drive shaft,

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Heritage 2018, 1 258 Figure 5. (a) Abu Ishmael mill. (b) El-Sheikh Ahmed mill.

Figure 6. El-Prince grain mill.

2. Materials and Methodology 2. Materials and Methodology

2.1. Description and Technical BackgroundBackground The simplest type of animal-powered mill is thethe gearless stone mill, known in antiquity as the “hourglass“hourglass mill”mill” [[5].5]. The animal-powered millmill inin DakhlaDakhla Oasis is a machine for converting the energy of animal-powered into useful forms of mechanical movement, usually in a grain mill. A grain mill consists of of a a wooden wooden gear gear wheel wheel (Perimeter (Perimeter = 6.20 = 6.20 m; Radius m; Radius = 95 =cm) 95 (usually cm) (usually constructed constructed from acacia from acaciawood), wood), with sixty with wooden sixty wooden sprockets sprockets (Length (Length = 31 cm; = Width 31 cm; = Width4 cm). =The 4 cm).wheel The is actually wheel is based actually on baseda wooden on a cross wooden and cross mounted and mounted horizontally horizontally on a vertical on a verticalshaft (a shaftdrive (ashaft) drive (Len shaft)gth (Length = 2.35 m; = 2.35Width m; Width= 27 cm), = 27 with cm), a withwooden a wooden finger fingerat the athole the under hole under the center the center of a large of a largehollow hollow wheel wheel,, with withits base its basepivoting pivoting on a wooden on a wooden concave concave base baseset in set the in middle the middle of a stone of a stone base. base. A drive A drive shaft shaftis rotated is rotated in a hole in a holeinside inside a “wooden a “wooden balance” balance” (Length (Length = 91 cm; = 91Width cm; Width= 0.22 cm) = 0.22 between cm) between the drive the shaft drive and shaft the wooden and the woodenpalm trunk palm which trunk bears which all bears the parts all the of partsthe mill of the (Len millgth (Length = 6.10 cm). = 6.10 In cm). the middle In the middle of the ofdrive the shaft, drive shaft, there is a wooden rod varying in length from 3 to 4 m, with a wooden stick placed on the bull’s necks, rotating in a circular track of mud-brick (Radius = 1.5 m; Height = 70 cm). The wheel is attached to one vertical driven gear, with 4 wooden teeth under the millstones; it consists of two circular stone, the upper stone “runner”, with a 43 cm perimeter, usually a little smaller than the lower stone, with Radius = 55 cm. The upper one has a slightly convex upper surface and rotates, while the lower one is normally fixed and attached to the vertical gear (pinion) by an ax. The vertical gear is based on a “nether balance” in its concave gap and jointed to the upper stone with a sword. The grains pour into the millstones wooden box (Hopper), which is fixed above them; it comes down to the millstone for grinding. Finally, flour comes down to a pot of pottery in a hole spanning a total depth of 35.50 cm (9.8 inches) called “Flour Home”.

2.2. Methodology The protection of cultural heritage is one of the most significant issues in the world. One of the most important issues in protecting cultural heritage is the difficulty in providing financial support. In fact, the preservation of the cultural heritage of the Oasis, including its traditional architecture and local structures, is the responsibility of international organizations interested in cultural heritage and workers in the field of cultural heritage protection. Moreover, the methodology of the research paper is based on the extent of compatibility between modern theories in the field of energy production Heritage 2018, 1 259 and the laws of gearing with the traditional experience of the old mill manufacturers in Dakhla Oasis, in addition to different scientific methods in restoration and rehabilitation. Furthermore, the study is based on the documentation of the human skills of the old craftsmen; most of these were no longer alive, except master craftsmen. Mr Mebarz Madani Mansour Issa Allam Al-Najjar, ninety-eight years old, is the last descendent of the Allam Al-Najjar family in Dakhla Oasis; this family made the grain mills and the wooden lintels in the towns of Dakhla Oasis. In addition, we adopted this traditional experience as a scientific and practical reference in the field of the grain mills restoration.

2.3. Mechanical Systems of Traditional Animal-Powered Mills Most visitors of old grain mills do not know the exact process of the millstones. There are several mechanical movements related to starting and stopping the old millstones [6]. A brief visual summary of the mechanical system of traditional animal-powered mills is provided in Figure7. Mechanical systems in the grinding process depend on the main mechanical movements of the traditional grain mills in Dakhla Oasis, from one part to another. A mechanical system in Dakhla Oasis grain mills uses animal power to accomplish a task that involves forces and movement in symmetry relationships between the hollow wheel (5) and the pinion jointed to the millstone, to achieve the desired forces and movement. In the beginning, the “miller” would open a bowl of grain and pour it into the millstone hopper (1). As a matter of fact, the first mechanical movement is based on the main drive shaft (3), a massive acacia pole, thus turning animal power into a main mechanical movement on its long axis attached to the wooden wheel, the drive shaft rotating freely with a wooden rod (4); this rod, placed on the bull’s neck, rotates in a circular track (2). The second mechanical movement is based on striking the pinion (12) under the millstone with a wooden wheel; such a wooden wheel would create great torque stresses for the pinion and the upper stone. The third mechanical movement is based on the upper millstone (6); the upper stone is rotating at 15 rpm, under steady steps, average for the bull, at a rate of 1 rpm of the wooden wheel in an anticlockwise direction. Finally, the last mechanical movement is based on the sword (9) attached to a “nether balance” (10) and the upper stone, in order to control the upper stone up and down. Such a process is needed in the production of flour for the desired grind grade. HeritageHeritage2018, 12018, 2, x FOR PEER REVIEW 6 of 18 260

Figure 7. (a) The major mechanisms of the grain mill. (b) Schematic of the elements of the working Figure 7. (a) The major mechanisms of the grain mill. (b) Schematic of the elements of the working system. system.

2.4. A2.4. Case A Case Study Study of the of Currentthe Current Status Status and and Deterioration Deterioration Factors of of Grain Grain Mills Mills in inDakhla Dakhla Oasis Oasis The studyThe study examined examined the current the current status status of 7 grain of 7 millsgrain (seemills Figure (see 8Figure) in Dakhla 8) in Oasis.Dakhla Particularly, Oasis. 6 of themParticularly, are located 6 of them in archaeological are located in archaeological cities and registered cities and registered as Islamic asmonuments Islamic monuments at the at Egyptian the MinistryEgyptian of Antiquities. Ministry of InAntiquities. addition, In 1 addition, grain mill 1 grain is located mill is within located the within ruins the of ruins the ancientof the ancient historical historical village in Dakhla Oasis, but not registered in the Islamic monuments at the Egyptian village in Dakhla Oasis, but not registered in the Islamic monuments at the Egyptian ministry ministry of antiquities. of antiquities.

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Figure 8. (aFigure) Photos 8. (a )of Photos a short of a short movie movie show show onon Yasser Yasser Ali’s Ali’s profile profile on LinkedIn on (bLinkedIn) Location of ( theb) grainLocation of the mills in Dakhla Oasis on the map of Dakhla Oasis on the Google Earth website. (c) Ground plan of grain mills inAbu Dakhla Ishmael’s Oasis grain mill.on the map of Dakhla Oasis on the Google Earth website. (c) Ground plan of Abu Ishmael’s grain mill. The “Best” grain mills are grain mill No. 1, named: “Abu Ishmael’s grain mill” in the ancient city The “Best”of Al-Qasr, grain after mills restoration are grain by the mill Egyptian No. 1, Ministry named: of Antiquities “Abu Ishmael’s and Social Fundgrain for mill” Development in the ancient city in 2015. Grain mill No. 2 is named: “El-Prince grain mill” in the ancient city of Balat after restoration of Al-Qasr, afterby the restoration Egyptian Ministry by the of Antiquities Egyptian in Ministry February 2017. of Antiquities and Social Fund for Development in 2015. Grain millThe “damaged”No. 2 is named: grain mills “El-Prince are grain mill grain No. 3, mill” named: in “El-Zinni the ancient grain mill” city in of Qasr, Balat and after grain restoration by the Egyptianmill No. Ministry 4, named: of “Sheikh Antiquities Ahmed grain in February mill”, also in2017. Qasr. The “damaged”Finally, thegrain “ruined” mills grain are mills grain are grainmill millNo. No. 3, 5,named: “without “El-Zinni name”, in the grain village mill” of Al-Hindaow, in Qasr, and grain grain mill No. 6, named: “Abu Yassin grain mill” in Balat, and grain mill No. 7, “without name”, mill No. 4, named:in Qasr. “Sheikh Ahmed grain mill”, also in Qasr. Finally, theThe “ruined” evaluation criteriagrain ofmills grain are mills grain in Dakhla mill Oasis No. that 5, were “without identified byname”, visual andin scientificthe village of Al- Hindaow, grainmethods mill are No. based 6, on named: the mechanical “Abu system Yassin that grai wasn damaged mill” in or not,Balat, restoration and grain and conservation mill No. 7, “without works, various degrees of damage, etc. name”, in Qasr.Fluctuating temperature, biological deterioration, and human activities are the main deterioration The evaluationfactors of grain criteria mills of in Dakhlagrain Oasis.mills in Dakhla Oasis that were identified by visual and scientific ◦ methods are basedTemperature on the in mechanical Dakhla Oasis cansystem rise up that to 50 wasC during damaged the day. or At not, night, restoration temperature can and drop conservation to below 15 ◦C; there is great variation in temperature during the day and night. In conservation science, works, various degrees of damage, etc. Fluctuating temperature, biological deterioration, and human activities are the main deterioration factors of grain mills in Dakhla Oasis. Temperature in Dakhla Oasis can rise up to 50 °C during the day. At night, temperature can drop to below 15 °C; there is great variation in temperature during the day and night. In conservation science, temperatures certainly play a large role in the damage to the grain mills’ wood. High temperatures produce a thermal energy; this leads to dimensional changes in physical properties, such as flexibility, rigidity, and the development of biological pests. With regard to the biological causes of wood deterioration, the main wood-destroying organisms in Dakhla Oasis are termites. Termites are soft-bodied social insects which feed on cellulose, although the gastric juices of most species do not contain celluloses. The presence of cellulose-digesting protozoa in their hindgut enables them to utilize wood as food. Because these one-celled animals play such an important role, termites are indirectly vulnerable to high temperatures and oxygen pressures [7].

Heritage 2018, 1 262 temperatures certainly play a large role in the damage to the grain mills’ wood. High temperatures produce a thermal energy; this leads to dimensional changes in physical properties, such as flexibility, rigidity, and the development of biological pests. With regard to the biological causes of wood deterioration, the main wood-destroying organisms in Dakhla Oasis are termites. Termites are soft-bodied social insects which feed on cellulose, although the gastric juices of most species do not contain celluloses. The presence of cellulose-digesting protozoa in their hindgut enables them to utilize wood as food. Because these one-celled animals play such an important role, termites are indirectly vulnerable to high temperatures and oxygen pressures [7]. In the opinion of the author, the relationship between human activities or man-made damages and local structures is mutually beneficial; more attention to the importance of local structures is given when a person derives a direct personal benefit. Therefore, the interests of citizens with grain mills in Dakhla Oasis remained conditional on their production of flour. As a final point, lack of cultural awareness causes severe damage to grain mills in Dakhla Oasis; grain mill structures for grinding grain are exposed to mechanical deterioration due to loads and stresses resulting from the wrong use of the mill, as well as using the wooden structures for other purposes.

2.5. The Scientific Method in the Restoration of Animal-Powered Mills in Dakhla Oasis There is no doubt that most countries around the world and the international organizations interested in preserving cultural heritage seek to restore traditional mills. Furthermore, once a mill has been restored wrong or incorrectly, it may be almost impossible to have it restored right. There are a great number of mills that have been restored incorrectly. These mills were just not that way originally [8]. The basic procedure for the restoration of old animal-powered mills starts with an in-depth look at its mechanical system philosophy, which lies behind all the difficult decisions. This is followed by an outline of the management of such a project and a description of all the other aspects and activities that are necessary for the successful outcome of any restoration project [9]. The society for the preservation of old mills (SPOOM) [10] shares common interests with the International Molinological Society (TIMS) [11] in promoting interest in old mills. David H. Jones is a Senior Lecturer in TIMS, who says: “What is the right way to preserve a mill? If we are taking this literally, we need not discuss it at all, because it does not exist. While there are plenty of wrong ways of treating mills, there is no single ‘right’ way, every preservation must be seen as a special case to be decided on its merits” [12]. To begin with, it is relatively easy to say there were animal-powered mills in Europe, Australia, the United States, and other countries during the nineteenth century. Sometimes, people interested in old animal-powered mills forget the formal documentation methods entirely; sometimes they don’t look at the writing about their experiences. At the same time, restoration experiences may not always be interchangeable. Based on these assumptions, sharing of practical experience and scientific expertise may be limited. However, to this end, the restoration project of the Volckerinckove horse mill in France [13] (see Figure9) is probably the closest model to other restoration experiences. Alongside all this tangible evidence, the mechanical movement is the basis of the restoration process in each animal-powered mill. Based on the foregoing observations, the restoration project of El-Prince Mill in Dakhla Oasis could be considered a scientific–practical reference for the restoration process of animal-powered mills and their mechanical systems in Egypt and other countries (Table1). Heritage 2018, 1 263 Heritage 2018, 2, x FOR PEER REVIEW 9 of 18

FigureFigure 9.9. ComparisonComparison betweenbetween the Horse-drawnHorse-drawn mill of Volckerinckove inin FranceFrance andand otherother animalanimal poweredpowered mills in our Oasis. There There are are some some copies copies in in Belgium. Belgium. Association Association Yser Yser Houck Houck rebuilt rebuilt it in it in2009–2010. 2009–2010.

2.5.1. Scientific DocumentationTable 1. The Restoration for El-Prince Diagram Mill of the traditional animal-powered mills. Quebec declaration pointed out that modern digital technology can be used efficiently and effectively in cultural heritage documentation [14]. In addition to artistic archaeological documentation, photographs were taken with a digital camera connected to a computer and video recorder. A “deterioration graphical profile” was designed by ArcGIS visualization software program in data analysis to evaluate the relationship between deterioration factors and deterioration patterns, as well as to choose the suitable conservation and interventions that should be applied. Additionally, an architectural documentation drawing was produced using SketchUp Pro 2016, to give an accurate visualization of the mill, including the details (see Figure 10).

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Figure 9. Comparison between the Horse-drawn mill of Volckerinckove in France and other animal powered mills in our Oasis. There are some copies in Belgium. Association Yser Houck rebuilt it in Heritage 2018, 1 264 2009–2010.

TableTable 1. 1.The The Restoration Restoration DiagramDiagram of the tr traditionaladitional animal-powered animal-powered mills. mills.

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2.5.1. Scientific Documentation for El-Prince Mill Quebec declaration pointed out that modern digital technology can be used efficiently and effectively in cultural heritage documentation [14]. In addition to artistic archaeological documentation, photographs were taken with a digital camera connected to a computer and video recorder. A “deterioration graphical profile” was designed by ArcGIS visualization software program in data analysis to evaluate the relationship between deterioration factors and deterioration patterns, as well as to choose the suitable conservation and interventions that should be applied. Additionally, an architectural documentation drawing was produced using SketchUp Pro 2016, to give an accurate visualization of the mill, including the details (see Figure 10).

Figure 10. (a) Showing the front view of the El-Prince Mill after drawing a graphical profile by ArcGIS Figure 10. (a) Showing the front view of the El-Prince Mill after drawing a graphical profile by ArcGIS visualization, data analysis. (b) Top view of the lower parts under the millstone, by SketchUp Pro visualization, data analysis. (b) Top view of the lower parts under the millstone, by SketchUp Pro 2016. 2016.

2.5.2. Physical and Mechanical Properties of Selected Wood Species in El-Prince Mill Acacia is a native wood in the El-Prince Mill. Three samples of damaged wood were examined in order to determine the physical and mechanical properties, and to choose the suitable conservation technique that should be applied. Consequently, the sizes of the samples are 3 cm × 3 cm × 3 cm, 2.05 cm × 2.05 × 2.05 cm, and 1.80 cm × 1.80 cm × 1.80 cm, respectively. In Table 2, analytical results referring to the acacia wood are dark brown, hardwood, moderately dense, and fine-grained. At the same time, there is low moisture content, specific gravity, and volumetric shrinkage. Finally, Acacia wood has generally been considered suitable for restoration and conservation.

Table 2. Average values of physical and mechanical properties.

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2.5.2. Physical and Mechanical Properties of Selected Wood Species in El-Prince Mill Acacia is a native wood in the El-Prince Mill. Three samples of damaged wood were examined in order to determine the physical and mechanical properties, and to choose the suitable conservation technique that should be applied. Consequently, the sizes of the samples are 3 cm × 3 cm × 3 cm, 2.05 cm × 2.05 × 2.05 cm, and 1.80 cm × 1.80 cm × 1.80 cm, respectively. In Table2, analytical results referring to the acacia wood are dark brown, hardwood, moderately dense, and fine-grained. At the same time, there is low moisture content, specific gravity, and volumetric shrinkage. Finally, Acacia wood has generally been considered suitable for restoration and conservation.

Heritage 2018, 2, x FOR PEER REVIEW 11 of 18 Table 2. Average values of physical and mechanical properties.

No. of Samples Sample Properties No. of Samples Sample Properties 1 2 3 Density (g/cm13) 2.05 2 1.08 1.05 3 Density (g/cm3) Porosity (%)2.05 0.21 1.08 0.15 0.12 1.05 Porosity (%)Moisture content 0.21 (%) 4.02 0.15 3.07 2.09 0.12 Moisture contentShrinkage (%) (tangential) 4.02 % 0.32 3.07 0.15 0.07 2.09 Shrinkage (tangential)Shrinkage % (radial) 0.32 % 0.22 0.15 0.12 0.01 0.07 Shrinkage (radial) %Hardness (kg) 0.22 17.04 0.12 15.03 12.34 0.01 Hardness (kg) 17.04 15.03 12.34 Stress (kg/cm2) 15.0 431.8 12.45 Stress (kg/cm2) 15.0 431.8 12.45

2.5.3. Mechanical and Chemical Cleaning 2.5.3. Mechanical and Chemical Cleaning For the purposes of mechanical cleaning, we used brushes, scalpels, and soft abrasives to remove the dirt,For thedust, purposes and other of mechanical surface deposits cleaning, accumula we usedted brushes, on wood scalpels, species and without soft abrasives any reach to remove to the thewood dirt, surface dust, and without other surface eroding deposits parts of accumulated the cell walls. on woodHowever, species chemical without cleaning any reach with toEthyl the woodalcohol surface (95%) andto remove without coating eroding material parts ofachieved the cell satisfying walls. However, results, and chemical this may cleaning need withto be Ethyltaken alcoholinto account (95%) for to the remove chemical coating compounds material used achieved in the satisfying invisible results,part. According and this mayto the need result to of be several taken intostudies, account Ethyl for alcohol the chemical had the compounds least influence used on in the invisiblesurface of part. archaeological According towood the result[15] (see of several Figure studies,11). Ethyl alcohol had the least influence on the surface of archaeological wood [15] (see Figure 11).

Figure 11. Cont.

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FigureFigure 11.11. ((aa)) MechanicalMechanical cleaning.cleaning. ((bb)) ChemicalChemical cleaning.cleaning. ((cc)) AfterAfter restoration.restoration.

2.5.4.2.5.4. Rehabilitation WoodWood StructuresStructures andand RestoringRestoring aa MechanicalMechanical MillMill MovementMovement byby LocalLocal Milling MillingExperts Experts AsAs wewe seesee inin Figure 1212,, the application of traditional expertise in rehabilitation andand restoringrestoring thethe mechanicalmechanical millmill movementmovement byby locallocal millsmills expertexpert MebarzMebarz MadaniMadani MansourMansour IssaIssa AllamAllam Al-NajjarAl-Najjar couldcould bebe summarizedsummarized asas follows:follows: (a)(a) The local expert adjusts adjusts the the perimeter perimeter of of the the adden addendumdum circle. circle. In In fact, fact, the the addendum addendum circle circle is isa circlea circle touching touching the the outermost outermost points points of of the the spro sprocketsckets of of the the wooden wooden gear gear wheel wheel (pitch circle). The local expert uses a wooden tool from a palm branch. The wooden tool end remains fixedfixed atat the circular track of the grain mill, and in front of a fixedfixed point at the other end, the wooden geargear rotates to determine the addendum circle from thethe correctcorrect perimeterperimeter [P[P == 6.20 m]. (b)(b) Next, use anan awlawl toto punchpunch aa wooden wooden scantling scantling in in the the center center between between every every two two gear gear sprockets sprockets to toadjust adjust the the proper proper spacing spacing between between the wooden the wooden gear sprockets. gear sprockets. This spacing This spacing is a preset is distancea preset distanceon the pitch on the circle. pitch Nine circle. centimeters Nine centimeters is just the is right just the spacing right inspacing every spacein every between space between the wooden the woodengear sprockets. gear sprockets. As an illustration, As an theillustration old craftsman, the usedold craftsman a wooden measuringused a wooden instrument measuring (closer instrumentto the Vernier (closer caliper to today), the Vernier designed caliper according today), to thedesigned proper according spacing between to the theproper wooden spacing gear betweensprockets the and wooden the beginning gear sprockets of the pinion and the tooth beginning when itof startsthe pinion running. tooth when it starts running. (c)(c) Reinstall the pinion gear down on the surface of thethe millstonemillstone toto 9090°◦ verticallyvertically andand rotaterotate 9090°◦ clockwise to transfer power to the upper millstone.

(d)(d) Reinstall the lower millstone (radius = 55 cm). In addition, reinstall the upperupper millstonemillstone andand install it with the pinion gear by an ax. (e) Animal-powered mills in Dakhla Oasis are made almost entirely of wood; after a long while, (e) Animal-powered mills in Dakhla Oasis are made almost entirely of wood; after a long while, these wooden parts can be worn down. Old Craftsman can often replace them with other parts these wooden parts can be worn down. Old Craftsman can often replace them with other parts in in a like-new condition with the same dimensions, or sometimes tweak the shape of the wooden

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Heritagea 2018 like-new, 2, x FOR condition PEER REVIEW with the same dimensions, or sometimes tweak the shape of the wooden13 of 18 gear sprockets. Old craftsmen are actually famous for offering a lifetime warranty on grain mills gearin Dakhla sprockets. Oasis. Old craftsmen are actually famous for offering a lifetime warranty on grain mills in Dakhla Oasis.

Figure 12. (a,b) Adjust the distances between the wooden Sprockets. ( (cc)) Adjust the perimeter of the Addendum circle. ( d,e) Reinstall the vertical gear. ((ff)) ReinstallReinstall thethe lowerlower stonestone ofof thethe millstone.millstone.

3. Results Results and and Discussion Discussion Animal-powered mills mills in in Dakhla Dakhla oasis oasis are are an an outstanding outstanding example example for forthe thebeginnings beginnings of the of old the millold millmanufacturers’ manufacturers’ knowledge knowledge of ofmechanical mechanical engineering engineering and and gears. gears. Indeed, Indeed, in in mechanical engineering, as as shown shown in in Figure Figure 13,13, it is possible to to say say “these are the simple gears”. Particularly, Particularly, wooden gear wheel No. 1 is called the driver andand vertical gear No. 2 is called the pinion.

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Figure 13. ((aa)) The The driver driver and and the the driven driven gear gear in in mechanical mechanical engineering. engineering. ( (b) The The driver driver and the driven . gear in animal-powered mill.mill

Let N1 = Speed of driver (rpm) [16]. Let N1 = Speed of driver (rpm) [16]. N2 = Speed of driven in (rpm) N2 = Speed of driven in (rpm) T1 = Number of teeth on gear 1 T1 = Number of teeth on gear 1 T2 = Number of teeth on gear 2 T = Number of teeth on gear 2 2 N T TrainTrain Value Value = 2 = =N 2 =2 T [17].2 [17 ]. N N1 T T1 Train Value1 = speed1 of driven = No.of teeth on driver = 60 = 15 speedspeed of driven of driver No.of. of teeth teethondriver on driven 4 60 TrainIt Value should = be noted that the = ratio of the speed of the driven= = to15 the speed of the driver is known as the train valuespeed of the of gear driver train. No. of teethondriven 4 The working speed for most draught animals is about 1 m/s (3.6 km/h, 2 mph) [18]. Therefore, It should be noted that the ratio of the speed of the driven to the speed of the driver is known as calculations of revolution per minute (rpm) in the Al-Prince mill, according to Kent’s Mechanical the train value of the gear train. Engineers Handbook 12th Edition [19], are as follow: The working speed for most draught animals is about 1 m/s (3.6 km/h, 2 mph) [18]. Therefore, Average of cow speed = 1 m/s, diameter of cow path = 9 m, diameter of millstone = 86 cm. calculations of revolution per minute (rpm) in the Al-Prince mill, according to Kent’s Mechanical When, in fact, the velocity of millstone: W1 = V/R = 1/15 = (0.666 rps/6.35 rpm) Engineers Handbook 12th Edition [19], are as follow: According to that, the Mechanical System in animal-powered mills in Dakhla Oasis is as follows: Average of cow speed = 1 m/s, diameter of cow path = 9 m, diameter of millstone = 86 cm. When, Free “software” of any animal-powered mill is the mechanical mill movement that transfers in fact, the velocity of millstone: W1 = V/R = 1/15 = (0.666 rps/6.35 rpm) animal power into motion that can be transmitted to the “Hardware” of the mill or the structures. According to that, the Mechanical System in animal-powered mills in Dakhla Oasis is as follows: When four sprockets of the wooden gear, which has sixty sprockets, are in its normal engaged Free “software” of any animal-powered mill is the mechanical mill movement that transfers position with pinion gear tooth (341.73 inches for everyone), they cause the wheel to revolve. This gives animal power into motion that can be transmitted to the “Hardware” of the mill or the structures. one turn of the upper millstone at the same time as the one turn of the wooden gear, which pushes the When four sprockets of the wooden gear, which has sixty sprockets, are in its normal engaged pinion gear. This gives a gear ratio of 15:1. For every one turn of the wooden gear, the pinion gear position with pinion gear tooth (341.73 inches for everyone), they cause the wheel to revolve. This rotates 15 times. gives one turn of the upper millstone at the same time as the one turn of the wooden gear, which Hence, the upper millstone would rotate at 0.66 revolutions per second (RPS) and at 95 to pushes the pinion gear. This gives a gear ratio of 15:1. For every one turn of the wooden gear, the 100 revolutions per minute (RPM), as opposed to 6.35 revolutions per minute (RPM) for the wooden pinion gear rotates 15 times. gear wheel. Hence, the upper millstone would rotate at 0.66 revolutions per second (RPS) and at 95 to 100 Application of traditional expertise enhances the positive role of civil society in the protection of revolutions per minute (RPM), as opposed to 6.35 revolutions per minute (RPM) for the wooden gear cultural heritage, with their experience in using mechanical engineering and mathematics. Adjusting wheel. the perimeter of the Addendum circle refers to the knowledge of the old mill manufacturers in Dakhla Application of traditional expertise enhances the positive role of civil society in the protection of cultural heritage, with their experience in using mechanical engineering and mathematics. Adjusting the perimeter of the Addendum circle refers to the knowledge of the old mill manufacturers in Dakhla

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Oasis on the tangent theory to a circle. A tangent to a circle is a line that intersects a circle in exactly one point (simply tangent),tangent), asas explainedexplained inin FigureFigure 1414[ 20[20].].

FigureFigure 14. 14. (a(a) )Tangent Tangent theory theory to to a a circle. circle. ( b) The same tangenttangent theorytheory toto aa circlecircle byby local local milling milling expert. expert.

The old carpenters in Dakhla Oasis defined defined the cu culturelture of the reduction pr processocess of wheat flours, flours, whichwhich express wheat flourflour particle size during the milling process and are composed of sizing, middling, andand finefine bran. That was before the knowledge of modern commercial mills, where the grain particlesparticles areare beingbeing exposedexposed toto strongstrong shear shear and and pressure pressure by by the the teeth teeth of of the the cylinder cylinder surface surface towards towards a milla mill nip nip area. area. Thus, Thus, the the old old grain grain mill mill manufactures manufactures in in Dakhla Dakhla OasisOasis usedused thethe swordsword attachedattached toto the pinionpinion andand upperupper stone.stone. It may be raised or lowered to alter the spacing between the millstones. Such a processprocess isis neededneeded inin thethe productionproduction ofof flourflour forfor thethe desireddesired grindgrind grade.grade. According to this, recentrecent scientificscientific research hashas demonstrateddemonstrated the effectivenesseffectiveness of the reductionreduction process onon thethe biochemicalbiochemical and technologicaltechnological properties of wheatwheat flours.flours. It definitelydefinitely affects dough propertiesproperties and quality of bread [[21].21]. The study ofof thethe mechanicalmechanical systemssystems ofof thethe traditionaltraditional animal-poweredanimal-powered mills in DakhlaDakhla OasisOasis adds background Information about the operatingoperating system of animal-powered mills in EgyptEgypt andand other countries. Aside from these considerations, TheThe target mechanism for this type of restorationrestoration ensures theirtheir survivalsurvival asas an an integral integral part part of of the the traditional traditional cultural cultural heritage heritage and and adding adding new new quality quality of archaeologicalof archaeological sites sites on on the the tourist tourist map. map. Restoration of the traditional grain mills in Dakhla Oasis played a dominant role in influencinginfluencing society withwith regardregard to to reinforcing reinforcing social social cohesion, cohesion, strengthening strengthening the sensethe sense of identity. of identity. Moreover, Moreover, grain millgrain restoration mill restoration projects projects are committed are committed to providing to employmentproviding employment opportunities opportunities to all unemployed to all unemployed youth. As a result, the conservation process trained local youths on techniques of

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Heritage 2018, 2, x FOR PEER REVIEW 16 of 18 youth. As a result, the conservation process trained local youths on techniques of rehabilitation of rehabilitationancient grain mills,of ancient which grain were mills, rehabilitated which were under rehabilitated the guidance under of the the Ministry guidance of Antiquitiesof the Ministry and of in Antiquitiescooperation and with in the cooperation New Valley with Governorate the New Valley (see Figure Governorate 15). (see Figure 15).

Figure 15. The diagram shows the number of participants in the restoration of the El-Prince Mill and Figure 15. The diagram shows the number of participants in the restoration of the El-Prince Mill and Abu Ishmael Mill in Dakhla Oasis under the guidance of the Ministry of Antiquities and in Abu Ishmael Mill in Dakhla Oasis under the guidance of the Ministry of Antiquities and in cooperation cooperation with the New Valley Governorate. with the New Valley Governorate.

In addition to these considerations, the grain mills in Dakhla Oasis and its traditional production structureIn addition attract local to these and considerations, foreign tourists the in grainall stag millses of in production, Dakhla Oasis such and as its an traditional olive mill productionbuilt in the 1860sstructure in Southern attract local France and and foreign the touristswater mill in all in stagesthe Antalya of production, Province, such Konyaalt as an oliveı County. mill builtTherefore, in the 1860sinternational in Southern organizations France and involved the water in millheritage in the conservation Antalya Province, must provide Konyaaltı financial County. and Therefore, moral supportinternational for the organizations conservation involved of these in rare heritage mills. conservation must provide financial and moral support for the conservation of these rare mills. 4. Conclusions 4. Conclusions The grain mills located in Dakhla Oasis in Egypt’s New Valley are one-of-a-kind models, which The grain mills located in Dakhla Oasis in Egypt’s New Valley are one-of-a-kind models, were, at one time, used for the production of flour, one of mankind’s staple nourishments. This study which were, at one time, used for the production of flour, one of mankind’s staple nourishments. investigated the strategies used to rehabilitate these mills. The investigation was based on the This study investigated the strategies used to rehabilitate these mills. The investigation was based on hypothesis that the restoration of the mills should combine logical, cutting-edge conservation and the hypothesis that the restoration of the mills should combine logical, cutting-edge conservation and preservation strategies with the traditional experience of old craftsmen. The research also examined preservation strategies with the traditional experience of old craftsmen. The research also examined the the significance of promoting the undocumented experience of these craftsmen, as well as the significance of promoting the undocumented experience of these craftsmen, as well as the utilization utilization of modern technology in the restoration and conservation of cultural heritage. of modern technology in the restoration and conservation of cultural heritage. The study presented a logical strategy for the conservation and protection of animal-powered The study presented a logical strategy for the conservation and protection of animal-powered mills mills and included an investigation of their mechanical systems, per the international charters and included an investigation of their mechanical systems, per the international charters governing governing restoration interventions. Additionally, all the scientific methods that could facilitate the restoration interventions. Additionally, all the scientific methods that could facilitate the examination examination and conservation of cultural heritage, as stipulated by the Venice Charter of 1964, were and conservation of cultural heritage, as stipulated by the Venice Charter of 1964, were utilized. utilized. The examples provided in this study delineated the significance of the grain mills as a feature of The examples provided in this study delineated the significance of the grain mills as a feature of the cultural heritage of the Egyptian Oasis, which is portrayed as in shortage and unique. Financial the cultural heritage of the Egyptian Oasis, which is portrayed as in shortage and unique. Financial assistance is needed from associations worldwide that focus on social legacy, as this would facilitate assistance is needed from associations worldwide that focus on social legacy, as this would facilitate the reclamation of the grain mills in Dakhla Oasis. the reclamation of the grain mills in Dakhla Oasis. The traditional technique of using animal power to transfer mechanical movement into millstones The traditional technique of using animal power to transfer mechanical movement into to grind wheat into flour can help us to understand the developments in the milling process to flour millstones to grind wheat into flour can help us to understand the developments in the milling mills and industrial mills. process to flour mills and industrial mills. In regard to the economic and social dimensions, reclamation would promote internal and external tourism, increase employment opportunities for young people, and improve the sustainability of traditional experience in the restoration of traditional heritage.

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In regard to the economic and social dimensions, reclamation would promote internal and external tourism, increase employment opportunities for young people, and improve the sustainability of traditional experience in the restoration of traditional heritage. On the whole, further research is needed to strengthen the mechanisms for the preservation of the grain mills in Dakhla Oasis, and this is expected to reinforce the instruments used in their conservation. If we take a last look back at a mill story, we can see the “miller” was feeding the grain slowly into the millstones and could weigh 100 kg or more, then begin a wooden wheel powered by animal power striking the driven gear at the point from one to two, the height of the pinion, causing the “runner” to revolve in a direction opposite to grinding 300 pounds or more of wheat in an hour. Time to try out the traditional mills in Dakhla Oasis!

Funding: This research received no external funding. Acknowledgments: We want to thank the protectors of civilization in Dakhla Oasis. In either case, a tribute to these men who are working in silence. Thanks to Mr. Haj Mebarz Madani Mansour Issa Allam Al-Najjar. Conflicts of Interest: The authors declare no conflict of interest.

References and Notes

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