Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/128/02/28/6383354/me-2006-feb3.pdf by guest on 26 September 2021

Victoria"n publicity: An idealized portrayal of the . ictor Hugo coined the phrase, "The detail in Atmospheric Railways by C. Hadfield (David and power of an idea whose time has come." Charles, Newton Abbot, 1967). This book not only gives The world has seen many ideas that were technical information, but also explores the cultural an­ powerful, some earthshaking, some tech­ thropology that went into arranging funding and wooing nological-democracy, the scientific method, the airplane, public support. The British government's involvement the Internet-but there have been other ideas that looked strongly resembled the politics now connected with the attractive but failed because of poor tin1i.ng. The so-called International Space Station. And as with NASA, railway "atmospheric railway," a 19th-century attempt by British developers had to solicit public support for their efforts. engineers to improve rail technology with the use of an Press releases were planted in the newspapers to arouse evacuated tube, was such a failure. public interest. An image used in the campaign was of a The middle of the 19th century was a great age for heroic figure at the front of a carriage. It represented a

engineering. The steam engine had allowed a growing driver of the who manipulated a valve and a brake. Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/128/02/28/6383354/me-2006-feb3.pdf by guest on 26 September 2021 network of rails to tie together a previously fragmented There was no other onboard machinery. island, so Britain as a whole was very optimistic about The effort to secure the public's approval involved ges­ rail technology. tures beyond spirited press releases. Britain was in the Engineers who built the railroads, however, were aware middle of the Gothic architectural revival and pumping of the limitations. The public distaste for smoke-belch­ stations were designed according to the rage. Many of ing locomotives could be surmounted, but mechanical the stations resembled a bad stage setting for Ivanhoe. constraints demanded something more than a publicity Experimentation with the "atmospheric" system began campaign. One factor that nothing could improve was in earnest in 1840 and led to successful passenger-carrying the coefficient of friction of metal wheels on metal in 1843. The initial work was done in Ireland at Dalkey. tracks. It limited traction and put a ceiling of about one The success in Ireland attracted the attention of Isam­ percent on the maximum grade that a conventionallo­ bard Kingdom BruneI, who had spearheaded the con­ comotive could negotiate. That greatly constrained struction of the a decade before. railbeds in hilly terrain. He became involved with the "atmospheric" concept in The "atmospheric" railway was conceived as a solution 1844, in the middle of a career that had begun in 1825, to both problems-public relations as well as mechanical. when he supervised construction of the Thames subway Coal-burning pumping stations could be located away tunnel at the age of 18. from urban centers and the prime mover did not depend BruneI initially toyed with the idea of producing a vac­ on the traction of wheels on track. Even now, we cannot uum without mechanical pumps, using Newcomen's say that it was a fundamentally bad idea. During its hey­ method of filling shells with low-pressure steam to dis­ day in Britain, from about 1843 to 1848, there were a place the air, then condensing the steam with water injec­ dozen or more separate lines. tion to create a . Ultimately, more conventional The Industrial Revolution began in Newcastle in 1710 pumps driven by steam engines were chosen. The very with the Newcomen steam engine, which depended on first versions were walking beam types in which recipro­ vacuum rather than high pressure. That may have made cating engine and pump cylinders were connected side Victorian engineers particularly conscious of vacuum­ by side with a pivoted beam, in an arrangement like that operated machines. used to pump water from mines. A more familiar The atmospheric railway depended on vacuum. It was a arrangement using rotating machinery was soon adopted. system very much like the pneumatic conveyors that were The 82Y2-horsepower engines had flywheels 25 feet in common everywhere until recent years. The heart of the diameter with connecting rods 20 feet long. The steam system was an evacuated tube about a foot in diameter. It cylinders were 40 inches in diameter and the pump was located between the tracks and stretched the entire cylinders 80 inches. The pistons had a stroke of 8 feet. length of the road. A piston driven by atmospheric pres­ They did not have piston rings, which were invented 10 sure moved inside the tube and was connected to the train years too late. by a strut running through a groove in the top of the tube. A very sophisticated valve cycling and timing arrange­ An elaborate zipper-like arrangement kept the tube ment was incorporated, however. The entire design may sealed on the vacuum side ahead of the piston, and open well have been analyzed using the work of Carnot, who for several feet behind it to allow air to enter. It is not in­ had published the cycle that bears his name in 1825, just tuitively obvious that this arrangement can generate a re­ a few years before. The ability to treat a heat engine spectable tractive force until one does the arithmetic. A mathematically was one piece of the puzzle that did ar­ 15-inch-diameter tube, for example, evacuated to about rive in time to be useful. half an atmosphere provides force on the order of 1,300 Iron casting had become a fine art by the time of the at­ pounds, which is quite adequate to move a small train. mospheric railway. Since wrought iron was more expen­ The atmospheric railway is documented in exhaustive sive than cast iron, bridges and large structures, such as the famous railway stations designed by BruneI, were being Robert Woods is a Fellow of ASME and a frequent contributor to Mechanical Engineering. Although it was some years ago that he visited the sites of BruneI" s triumphs in Britain. he only made increasingly of cast iron. A decade later, this tech­ recently learned of the atmospheric railway. It is not advertised as one of Brunel"s big successes. nology was raised to a high point in the United States,

mechanical engineering February 2006 29 where the dome of the U.S. Capitol was made of cast iron. to be opened in succession, was a qualified success. Later, The tubes for the atmospheric railway were cast iron, an engineer named Hallett proposed a geometry shaped delivered in nine-foot lengths and bolted together. A large much like that now used on aircraft carriers. It had a plate valve at each station isolated the approximately three miles running between two inflated rubber tubes that ran the of line being served by each entire length of the system. That sub­ pump. Synchronizing the stituted a continuous slide for a domi­ operation of valves and no-like progression. It probably pumps with train motion would have worked, but by the time it was critical. A first genera­ was proposed, the atmospheric rail­ tion of telegraphy was avail­ road was already doomed able to coordinate the tim­ As much of a handicap as the prim­ ing over distances, but al­ itive seal material was the state of lu­ though it was being used brication. Oil, which would have Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/128/02/28/6383354/me-2006-feb3.pdf by guest on 26 September 2021 successfully on other lines, been useful, first became commer­ BruneI appears not to have cially available from wells in Pennsyl­ trusted it and relied instead vania in 1859, just as the final branch on a printed schedule. That of the last line closed. Grease, made was ~ery inefficient, result­ by bulking oil with additives to make ing in the pumps running it more viscous, and the ubiquitous when they were not needed. grease cup, were not to be invented . The key to the overall op­ for another decade. eration was a means of seal­ Victorian engineers were limited to ing the longitudinal gap in the millennia-old choices of animal the tube while allowing a fat and tallow, which, along with the strut to pass through. This properties of leather, proved to be a arrangement is conceptually real problem. In addition to being similar to the one used today short-lived, thus requiring an ongo- to catapult shipborne air­ ing expenditure of craft. It posed a major chal­ manpower to apply LEATHER COMPOSITION lenge to Victorian-era engineers. IRON lubricant over the Even with the technology now length of the line, available, there is still substantial the leather/animal leakage in shipboard catapults, fat combination which operate with pressure in­ was prone to freez­ stead of vacuum. In modern equip­ ing in winter and ment the steam generators can be the leather to fa­

sized to overwhelm any predictable The railway relied on a vacuum tube beneath coaches. The method of sealing tiglle failure even at leakage. The Victorian engineers the system proved to be one of the weak points of the scheme. room temperature. didn't have the advantage of brute · Beyond that, a force and fought a losing battle to seal their system. problem today's tribologist does not often face was that of Lubrication of the sliding seals and choice of materials rats eating the gaskets. In the case of one line, the 20-mile were questions to which the answers also arrived a few South Devon, replacing the gaskets cost 1,018 pounds. years too late. The vulcanization process for rubber was That may well have been the final nail in the coffin of that discovered at exactly the same time that experimentation particular run, which had initially cost on the order of on the atmospheric railway began in 1840. 43,400 pounds. To put this in perspective, a well-paid ex­ Since rubber was not initially available as a choice for ecutive of the time was paid 300 pounds per year. flexible seal components, the only alternative was Charles Fort, a 1920s newspaperman and a keen ob­ leather. That led to some bizarre-looking arrangements server of human history, noted that when the time has in which the slots were sealed by leather flaps, which come to "steam engine," the human race will "steam were raised locally as the strut passed through them. An engine." That was a whimsical way of saying that when elaborate arrangement was contrived to hold open all of the technology exists, it is inevitable that some­ roughly a 15-foot length of the valve behind the piston, body-almost anybody-will put the pieces together allowing air to enter and provide the necessary pressure and bring on a new epoch. The unstated corollary is that differential. Force to reseal the gasket was accomplished ifless than all of the technology exists, some humans can by a following set of wheels that pressed the leather valve waste a lot of effort and accomplish nothing lasting. The into a sealing matrix of beeswax and tallow. To render atmospheric railway was not a success and it cost a lot of the seal more pliable, a heater filled with smoldering people a great deal, both in money and in reputation. It charcoal sometimes followed. failed because there were pieces missing. Ironically, all of The seal, which involved a series ofleather flaps that had those pieces arrived j list a few years later. •

30 February 2006 mechanical engineering