Chapter 2

In addition to the element of potential danger from careless operation or failure of the brake, the Baldwin system was extremely expensive to install as a result of the second shaft, which of course was required to be more or less watertight.

Much of the water-balance elevator's development and refinement was done by William E. Hale of Chicago, who also made most of the installations. The system has, therefore, come to bear his name more commonly than Baldwin's.

The popularity of the water-balance system waned after only a few years, being eclipsed by more rational systems. Hale eventually abandoned it and became the western agent for Otis--by this time prominent in the field--and subsequently was influential in development of the hydraulic elevator.

The rope-geared system of hydraulic elevator operation was so basically simple that by 1880 it had been embraced by virtually all manufacturers. However, for years most builders continued to maintain a line of steam and belt driven machines for freight service. Inspired by the rapid increase of taller and taller buildings, there was a concentrated effort, heightened by severe competition, to refine the basic system.

By the late 1880's a vast number of improvements in detail had appeared, and this form of elevator was considered to be almost without defect. It was safe. Absence of a drum enabled the car to be carried by a number of cables rather than by one or two, and rendered overtravel impossible. It was fast. Control devices had received probably the most attention by engineers and were as perfect and sensitive as was possible with mechanical means. Cars with lever control could be run at the high speeds required for high buildings, yet they could be stopped with a smoothness and precision unattainable earlier with systems in which the valves were controlled by an endless rope, worked by the operator. It was almost completely silent, and when the cylinder was placed vertically in a well near the shaft, practically no valuable floor space was occupied. But most important, the length of rise was unlimited because no drum was used. As greater rises were required, the multiplication of the ropes and sheaves was simply increased, raising the piston-car travel ratio and permitting the cylinder to remain of manageable length. The ratio was often as high as 10 or 12 to 1, the car moving 10 or 12 feet to the piston's 1.

In addition to its principal advantages, the hydraulic elevator could be operated directly from municipal water mains in the many cities where there was sufficient pressure, thus eliminating a large investment in tanks, pumps and boilers (fig. 14).

By far the greatest development in this specialized branch of mechanical engineering occurred in the United States. The comparative position of American practice, which will be demonstrated farther on, is indicated by the fact that Otis Brothers and other large elevator concerns in the United States were able to establish offices in many of the major cities of Europe and compete very successfully with local firms in spite of the higher costs due to shipment. This also demonstrates the extent of error in the oft-heard statement that the skyscraper was the direct result of the elevator's invention. There is no question that continued elevator improvement was an essential factor in the rapid increase of building heights. However, consideration of the situation in European cities, where buildings of over 10 stories were (and still are) rare in spite of the availability of similar elevator techniques, points to the fundamental matter of tradition. The European city simply did not develop with the lack of judicial restraint which characterized metropolitan growth in the United States. The American tendency to confine mercantile activity to the smallest possible area resulted in excessive land values, which drove buildings skyward. The elevator followed, or, at most, kept pace with, the development of higher buildings.

European elevator development--notwithstanding the number of American rope-geared hydraulic machines sold in Europe in the 10 years or so preceding the Paris fair of 1889--was confined mainly to variations on the direct plunger type, which was first used in English factories in the 1830's. The plunger elevator (fig. 16), an even closer derivative of the hydraulic press than Armstrong's crane, was nothing more than a platform on the upper end of a vertical plunger that rose from a cylinder as water was forced in.

There were two reasons for this European practice. The first and most apparent was the rarity of tall buildings. The drilling of a well to receive the cylinder was thus a matter of little difficulty. This well had to be equivalent in depth to the elevator rise. The second reason was an innate European distrust of cable-hung elevator systems in any form, an attitude that will be discussed more fully farther on.

THE ELECTRIC ELEVATOR

At the time the Eiffel Tower elevators were under consideration, water under pressure was, from a practical standpoint, the only agent capable of fulfilling the power and control requirements of this particularly severe service. Steam, as previously mentioned, had already been found wanting in several respects. Electricity, on the other hand, seemed to hold promise for almost every field of human endeavor. By 1888 the electric motor had behind it a 10- or 15-year history of active development. Frank J. Sprague had already placed in successful operation a sizable electric trolley-car system, and was manufacturing motors of up to 20 horsepower in commercial quantity. Lighting generators were being produced in sizes far greater. There were, nevertheless, many obstacles preventing the translation of this progress into machinery capable of hauling large groups of people a vertical distance of 1,000 feet with unquestionable dependability.

The first application of electricity to elevator propulsion was an experiment of the distinguished German electrician Werner von Siemens, who, in 1880, constructed a car that successfully climbed a rack by means of a motor and worm gearing beneath its deck (figs. 17, 18)--again, the characteristic European distrust of cable suspension. However, the effect of this success on subsequent development was negligible. Significant use of electricity in this field occurred somewhat later, and in a manner parallel to that by which steam was first applied to the elevator--the driving of mechanical (belt driven) elevator machines by individual motors. Slightly later came another application of the "conversion" type. This was the simple substitution of electrically driven pumps (fig. 21) for steam pumps in hydraulic installations. It will be recalled that pumps were necessary in cases where water main pressure was insufficient to operate the elevator directly.

In both of these cases the operational demands on the motor were of course identical to those on the prime movers which they replaced; no reversal of direction was necessary, the speed was constant, and the load was nearly constant. Furthermore, the load could be applied to the motor gradually through automatic relief valves on the pump and in the mechanical machines by slippage as the belt was shifted from the loose to the fast pulleys. The ultimate simplicity in control resulted from permitting the motor to run continuously, drawing current only in proportion to its loading. The direct-current motor of the 1880's was easily capable of such service, and it was widely used in this way.

Adaptation of the motor to the direct drive of an elevator machine was quite another matter, the difficulties being largely those of control. At this time the only practical means of starting a motor under load was by introducing resistance into the circuit and cutting it out in a series of steps as the speed picked up; precisely the method used to start traction motors. In the early attempts to couple the motor directly to the winding drum through worm gearing, this "notching up" was transmitted to the car as a jerking motion, disagreeable to passengers and hard on machinery. Furthermore, the controller contacts had a short life because of the arcing which resulted from heavy starting currents. In all, such systems were unsatisfactory and generally unreliable, and were held in disfavor by both elevator experts and owners.

There was, moreover, little inducement to overcome the problem of control and other minor problems because of a more serious difficulty which had persisted since the days of steam. This was the matter of the drum and its attendant limitations. The motor's action being rotatory, the winding drum was the only practical way in which to apply its motive power to hoisting. This single fact shut electricity almost completely out of any large-scale elevator business until after the turn of the century. True, there was a certain amount of development, after about 1887, of the electric worm-drive drum machine for slow-speed, low-rise service (fig. 19). But the first installation of this type that was considered practically successful--in that it was in continuous use for a long period--was not made until 1889,[7] the year in which the Eiffel Tower was completed.

Pertinent is the one nearly successful attempt which was made to approach the high-rise problem electrically. In 1888, Charles R. Pratt, an elevator engineer of Montclair, New Jersey, invented a machine based on the horizontal cylinder rope-geared hydraulic elevator, in which the two sets of sheaves were drawn apart by a screw and traveling nut. The screw was revolved directly by a Sprague motor, the system being known as the Sprague-Pratt. While a number of installations were made, the machine was subject to several serious mechanical faults and passed out of use around 1900. Generally, electricity as a practical workable power for elevators seemed to hold little promise in 1888.[8]

The Tower's Elevators

A great part of the Eiffel Tower's worth and its _raison d'être_ lay in the overwhelming visual power by which it was to symbolize to a world audience the scientific, artistic, and, above all, the technical achievements of the French Republic. Another consideration, in Eiffel's opinion, was its great potential value as a scientific observatory. At its summit grand experiments and observations would be possible in such fields as meteorology and astronomy. In this respect it was welcomed as a tremendous improvement over the balloon and steam winch that had been featured in this service at the 1878 Paris exposition. Experiments were also to be conducted on the electrical illumination of cities from great heights. The great strategic value of the Tower as an observation post also was recognized. But from the beginning, sight was never lost of the structure's great value as an unprecedented public attraction, and its systematic exploitation in this manner played a part in its planning, second perhaps only to the basic design.

The conveyance of multitudes of visitors to the Tower's first or main platform and a somewhat lesser number to the summit was a technical problem whose seriousness Eiffel must certainly have been aware of at the project's onset. While a few visitors could be expected to walk to the first or possibly second stage, 377 feet above the ground, the main means of transport obviously had to be elevators. Indeed, the two aspects of the Tower with which the Exposition commissioners were most deeply concerned were the adequate grounding of lightning and the provision of a reliable system of elevators, which they insisted be unconditionally safe.

To study the elevator problem, Eiffel retained a man named Backmann who was considered an expert on the subject. Apparently Backmann originally was to design the complete system, but he was to prove inadequate to the task. As his few schemes are studied it becomes increasingly difficult to imagine by what qualifications he was regarded as either an elevator expert or designer by Eiffel and the Commission. His proposals appear, with one exception, to have been decidedly retrogressive, and, further, to incorporate the most undesirable features of those earlier systems he chose to borrow from. Nothing has been discovered regarding his work, if any, on elevators for the lower section of the Tower. Realizing the difficulty of this aspect of the problem, he may not have attempted its solution, and confined his work to the upper half where the structure permitted a straight, vertical run.

The Backmann design for the upper elevators was based upon a principle which had been attractive to many inventors in the mid-19th century period of elevator development--that of "screwing the car up" by means of a threaded element and a nut, either of which might be rotated and the other remain stationary. The analogy to a nut and bolt made the scheme an obvious one at that early time, but its inherent complexity soon became equally evident and it never achieved practical success. Backmann projected two cylindrical cars that traveled in parallel shafts and balanced one another from opposite ends of common cables that passed over a sheave in the upperworks. Around the inside of each shaft extended a spiral track upon which ran rollers attached to revolving frames underneath the cars. When the frames were made to revolve, the rollers, running around the track, would raise or lower one car, the other traveling in the opposite direction (fig. 23).

In the plan as first presented, a ground-based steam engine drove the frames and rollers through an endless fly rope--traveling at high speed presumably to permit it to be of small diameter and still transmit a reasonable amount of power--which engaged pulleys on the cars. The design was remarkably similar to that of the Miller Patent Screw Hoisting Machine, which had had a brief life in the United States around 1865. The Miller system (see p. 19) used a flat belt rather than a rope (fig. 20). This plan was quickly rejected, probably because of anticipated difficulties with the rope transmission.[9]

Backmann's second proposal, actually approved by the Commission, incorporated the only--although highly significant--innovation evident in his designs. For the rope transmission, electric motors were substituted, one in each car to drive the roller frame directly. With this modification, the plan does not seem quite as unreasonable, and would probably have worked. However, it would certainly have lacked the necessary durability and would have been extremely expensive. The Commission discarded the whole scheme about the middle of 1888, giving two reasons for its action: (1) the novelty of the system and the attendant possibility of stoppages which might seriously interrupt the "exploitation of the Tower," and (2) fear that the rollers running around the tracks would cause excessive noise and vibration. Both reasons seem quite incredible when the Backmann system is compared to one of those actually used--the Roux, described below--which obviously must have been subject to identical failings, and on a far greater scale. More likely there existed an unspoken distrust of electric propulsion.

That the Backmann system should have been given serious consideration at all reflects the uncertainty surrounding the entire matter of providing elevator service of such unusual nature. Had the Eiffel Tower been erected only 15 years later, the situation would have been simply one of selection. As it was, Eiffel and the commissioners were governed not by what they wanted but largely by what was available.

THE OTIS SYSTEM

The curvature of the Tower's legs imposed a problem unique in elevator design, and it caused great annoyance to Eiffel, the fair's Commission, and all others concerned. Since a vertical shaftway anywhere within the open area beneath the first platform was esthetically unthinkable, the elevators could be placed only in the inclined legs. The problem of reaching the first platform was not serious. The legs were wide enough and their curvature so slight in this lower portion as to permit them to contain a straight run of track, and the service could have been designed along the lines of an ordinary inclined railway. It was estimated that the great majority of visitors would go only to this level, attracted by the several international restaurants, bars and other features located there. Two elevators to operate only that far were contracted for with no difficulty--one to be placed in the east leg and one in the west.

To transport people to the second platform was an altogether different problem. Since there was to be a single run from the ground, it would have been necessary to form the elevator guides either with a constant curvature, approximating that of the legs, or with a series of straight chords connected by short segmental curves of small radius. Eiffel planned initially to use the first method, but the second was adopted ultimately, probably as being the simpler because only two straight lengths of run were found to be necessary.

Bids were invited for two elevators on this basis--one each for the north and south legs. Here the unprecedented character of the matter became evident--there was not a firm in France willing to undertake the work. The American Elevator Company, the European branch of Otis Brothers & Company, did submit a proposal through its Paris office, Otis Ascenseur Cie., but the Commission was compelled to reject it because a clause in the fair's charter prohibited the use of any foreign material in the construction of the Tower. Furthermore, there was a strong prejudice against foreign contractors, which, because of the general background of disfavor surrounding the project during its early stages, was an element worth serious consideration by the Commission. The bidding time was extended, and many attempts were made to attract a native design but none was forthcoming.

As time grew short, it became imperative to resolve the matter, and the Commission, in desperation, awarded the contract to Otis in July 1887 for the amount of $22,500.[10] A curious footnote to the affair appeared much later in the form of a published interview[11] with W. Frank Hall, Otis' Paris representative:

"Yes," said Mr. Hall, "this is the first elevator of its kind. Our people for thirty-eight years have been doing this work, and have constructed thousands of elevators vertically, and many on an incline, but never one to strike a radius of 160 feet for a distance of over 50 feet. It has required a great amount of preparatory study and we have worked on it for three years."

"That was before you got the contract?"

"Quite so, but we knew that, although the French authorities were very reluctant to give away this piece of work, they would be bound to come to us, and so we were preparing for them."

Such supreme confidence must have rapidly evaporated as events progressed. Despite the invaluable advertising to be derived from an installation of such distinction, the Otises would probably have defaulted had they foreseen the difficulties which preceded completion of the work.