Elevator Systems of the Eiffel Tower, 1889 (2024)

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ELEVATOR SYSTEMS of the EIFFEL TOWER, 1889

By Robert M. Vogel

The 1,000-foot tower that formed the focal point and central feature ofthe Universal Exposition of 1889 at Paris has become one of the best knownof man’s works. It was among the most outstanding technologicalachievements of an age which was itself remarkable for such achievements.

Second to the interest shown in the tower’s structural aspects was theinterest in its mechanical organs. Of these, the most exceptional were thethree separate elevator systems by which the upper levels were madeaccessible to the Exposition visitors. The design of these systemsinvolved problems far greater than had been encountered in previouselevator work anywhere in the world. The basis of these difficulties wasthe amplification of the two conditions that were the normal determinantsin elevator design—passenger capacity and height of rise. In addition,there was the problem, totally new, of fitting elevator shafts to thecurvature of the Tower’s legs. The study of the various solutions to theseproblems presents a concise view of the capabilities of the elevator artjust prior to the beginning of the most recent phase of its development,marked by the entry of electricity into the field.

The great confidence of the Tower’s builder in his own engineering abilitycan be fully appreciated, however, only when notice is taken of oneexceptional way in which the project differed from works of earlierperiods as well as from contemporary ones. In almost every case, theseother works had evolved, in a natural and progressive way, from afundamental concept firmly based upon precedent. This was true of suchnotable structures of the time as the Brooklyn Bridge and, to a lesserextent, the Forth Bridge. For the design of his tower, there was virtuallyno experience in structural history from which Eiffel could draw otherthan a series of high piers that his own firm had designed earlier forrailway bridges. It was these designs that led Eiffel to consider thepracticality of iron structures of extreme height.

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Figure 1.—The Eiffel Tower at the time of the
Universal Expositionof 1889 at Paris.
(From La Nature, June 29, 1889, vol. 17, p. 73.)

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Figure 2.—Gustave Eiffel (1832-1923).
(From GustaveEiffel, La Tour de Trois Cents Mètres,
Paris, 1900, frontispiece.)

There was, it is true, some inspiration to be found in the paper projectsof several earlier designers—themselves inspired by that compulsion whichthroughout history seems to have driven men to attempt the erection ofmagnificently high structures.

One such inspiration was a proposal made in 1832 by the celebrated buteccentric Welsh engineer Richard Trevithick to erect a 1,000-foot,conical, cast-iron tower (fig. 3) to celebrate the passing of the ReformBill. Of particular interest in light of the present discussion wasTrevithick’s plan to raise visitors to the summit on a piston, drivenupward within the structure’s hollow central tube by compressed air. Itprobably is fortunate for Trevithick’s reputation that his plan diedshortly after this and the project was forgotten.

One project of genuine promise was a tower proposed by the eminentAmerican engineering firm of Clarke, Reeves & Company to be erected at theCentennial Exhibition at Philadelphia in 1876. At the time, this firm wasperhaps the leading designer and erector of iron structures in the UnitedStates, having executed such works as the Girard Avenue Bridge over theSchuylkill at Fairmount Park, and most of New York’s early elevatedrailway system. The company’s proposal (fig. 4) for a 1,000-foot shaft ofwrought-iron columns braced by a continuous web of diagonals was basedupon sound theoretical knowledge and practical experience. Nevertheless,the natural hesitation that the fair’s sponsors apparently felt in theface of so heroic a scheme could not be overcome, and this project alsoremained a vision.

Preparatory Work for the Tower

In the year 1885, the Eiffel firm, which also had an extensive backgroundof experience in structural engineering, undertook a series ofinvestigations of tall metallic piers based upon its recent experienceswith several lofty railway viaducts and bridges. The most spectacular ofthese was the famous Garabit Viaduct (1880-1884), which carries a railroadsome 400 feet above the valley of the Truyere in southern France. Whilethe 200-foot height of the viaduct’s two greatest piers was not startlingeven at that period, the studies proved that piers of far greater heightwere entirely feasible in iron construction. This led to the design of a395-foot pier, which, although never incorporated into a bridge, may besaid to have been the direct basis for the Eiffel Tower.

Preliminary studies for a 300-meter tower were made with the 1889 fairimmediately in mind. With an assurance born of positive knowledge, Eiffelin June of 1886 approached the Exposition commissioners with the project.There can be no doubt that only the singular respect with which Eiffel wasregarded not only by his profession but by the entire nation motivated theCommission to approve a plan which, in the hands of a figure of lessstature, would have been considered grossly impractical.

Between this time and commencement of the Tower’s construction at the endof January 1887, there arose one of the most persistently annoying of thenumerous difficulties, both structural and social, which confronted Eiffelas the project advanced. In the wake of the initial enthusiasm—on thepart of the fair’s Commission inspired by the desire to create a monumentto French technological achievement, and on the[Pg 5] part of the majority ofFrenchmen by the stirring of their imagination at the magnitude of thestructure—there grew a rising movement of disfavor. The nucleus was, notsurprisingly, formed mainly of the intelligentsia, but objections weremade by prominent Frenchmen in all walks of life. The most interestingpoint to be noted in a retrospection of this often violent opposition wasthat, although the Tower’s every aspect was attacked, there was remarkablylittle criticism of its structural feasibility, either by the engineeringprofession or, as seems traditionally to be the case with bold andunprecedented undertakings, by large numbers of the technically uninformedlaity. True, there was an undercurrent of what might be characterized asunease by many property owners in the structure’s shadow, but the mostobstinate element of resistance was that which deplored the Tower as amechanistic intrusion upon the architectural and natural beauties ofParis. This resistance voiced its fury in a flood of special newspapereditions, petitions, and manifestos signed by such lights of the fine andliterary arts as De Maupassant, Gounod, Dumas fils, and others. Theeloquence of one article, which appeared in several Paris papers inFebruary 1887, was typical:

We protest in the name of French taste and the national art cultureagainst the erection of a staggering Tower, like a gigantic kitchenchimney dominating Paris, eclipsing by its barbarous mass Notre Dame,the Sainte-Chapelle, the tower of St. Jacques, the Dôme desInvalides, the Arc de Triomphe, humiliating these monuments by an actof madness.[1]

Further, a prediction was made that the entire city would becomedishonored by the odious shadow of the odious column of bolted sheet iron.

It is impossible to determine what influence these outcries might have hadon the project had they been organized sooner. But inasmuch as theCommission had, in November 1886, provided 1,500,000 francs for itscommencement, the work had been fairly launched by the time theprotestations became loud enough to threaten and they were ineffectual.

Upon completion, many of the most vigorous protestants became as vigorousin their praise of the Tower, but a hard core of critics continued forseveral years to circulate petitions advocating its demolition by thegovernment. One of these critics, it was said—probably apocryphally—tookan office on the first platform, that being the only place in Paris fromwhich the Tower could not be seen.

Figure 3.— proposed cast-iron tower (1832)
would have been 1,000 feet high, 100 feet in diameter at the base,
12 feetat the top, and surmounted by a colossal statue.
(From F. Dye, Popular Engineering, London, 1895, p. 205.)

The Tower’s Structural Rationale

During the previously mentioned studies of high piers undertaken by theEiffel firm, it was established that as the base width of these piersincreased in proportion to their height, the diagonal bracing connectingthe vertical members, necessary for rigidity, became so long as to besubject to high flexural stresses from wind and columnar loading. Toresist these stresses, the bracing required extremely large sections whichgreatly increased the surface of the structure exposed to the wind, andwas, moreover, decidedly uneconomical. To overcome this difficulty, theprinciple which became the basic design concept of the Tower wasdeveloped.

The material which would otherwise have been used for the continuouslattice of diagonal bracing was concentrated in the four corner columns ofthe Tower, and these verticals were connected only at[Pg 6] two widelyseparated points by the deep bands of trussing which formed the first andsecond platforms. A slight curvature inward was given to the main piers tofurther widen the base and increase the stability of the structure. At apoint slightly above the second platform, the four members converged tothe extent that conventional bracing became more economical, and they werejoined.

Figure 4.—The proposed 1,000-foot iron tower designed by
Clarke, Reeves & Co. for the Centennial Exhibition of 1876 atPhiladelphia.
(From Scientific American, Jan. 24, 1874, vol. 30, p. 47.)

That this theory was successful not only practically, but visually, isevident from the resulting work. The curve of the legs and the openingsbeneath the two lower platforms are primarily responsible for the Tower’sgraceful beauty as well as for its structural soundness.

The design of the Tower was not actually the work of Eiffel himself but oftwo of his chief engineers, Emile Nouguier (1840-?) and Maurice Kœchlin(1856-1946)—the men who had conducted the high pier studies—and thearchitect Stéphen Sauvestre (1847-?).

In the planning of the foundations, extreme care was used to ensureadequate footing, but in spite of the Tower’s light weight in proportionto its bulk, and the low earth pressure it exerted, uneven pier settlementwith resultant leaning of the Tower was considered a dangerouspossibility.[2] To compensate for this eventuality, a device was usedwhose ingenious directness justifies a brief description. In the base ofeach of the 16 columns forming the four main legs was incorporated anopening into which an 800-ton hydraulic press could be placed, capable ofraising the member slightly. A thin steel shim could then be inserted tomake the necessary correction (fig. 5). The system was used only duringconstruction to overcome minor erection discrepancies.

In order to appreciate fully the problem which confronted the Tower’sdesigners and sponsors when they turned to the problem of making itsobservation areas accessible to the fair’s visitors, it is first necessaryto investigate briefly the contemporary state of elevator art.

Elevator Development before the Tower

While power-driven hoists and elevators in many forms had been used sincethe early years of the 19th century, the ever-present possibility ofbreakage of the hoisting rope restricted their use almost entirely to thehandling of goods in mills and warehouses.[3] Not until the invention of adevice which would positively prevent this was there much basis for workon other elements of the system. The first workable mechanism to preventthe car from dropping to the bottom of the hoistway in event of ropefailure was the product of Elisha G. Otis (1811-1861), a mechanic ofYonkers, New York. The invention was made more or less as a matter ofcourse along with the other machinery for a new mattress factory of whichOtis was master mechanic.

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Figure 5.—Correcting erection discrepancies by raising pier member—withhydraulic press and hand pump—and inserting shims.
(From La Nature, Feb. 18, 1888, vol. 16, p. 184.)

Figure 6.—The promenade beneath the Eiffel Tower, 1889. (From La Nature, Nov. 30, 1889, vol. 17, p. 425.)

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Figure 7.—Teagle elevator in an English mill about 1845. Power was taken fromthe line shafting.
(From Pictorial Gallery of Arts, Volume of Useful Arts, London, n.d. [ca. 1845].)

The importance of this invention soon became evident to Otis, and heintroduced his device to the public three years later during the secondseason of the New York Crystal Palace Exhibition, in 1854. Here he woulddemonstrate dramatically the perfect safety of his elevator by cutting thehoisting rope of a suspended platform on which he himself stood, utteringthe immortal words which have come to be inseparably associated with thehistory of the elevator—“All safe, gentlemen!”[4]

The invention achieved popularity slowly, but did find increasing favor inmanufactories throughout the eastern United States. The significance ofOtis’ early work in this field lay strictly in the safety features of hiselevators rather than in the hoisting equipment. His earliest systems wereoperated by machinery similar to that of the teagle elevator in which thehoisting drum was driven from the mill shafting by simple fast and loosepulleys with crossed and straight belts to raise, lower, and stop. Thisscheme, already common at the time, was itself a direct improvement on theancient hand-powered drum hoist.

The first complete elevator machine in the United States, constructed in1855, was a complex and inefficient contrivance built around anoscillating-cylinder steam engine. The advantages of an elevator systemindependent of the mill drive quickly became apparent, and by 1860improved steam elevator machines were being produced in some quantity, butalmost exclusively for freight service. It is not clear when the firstelevator was installed explicitly for passenger service, but it wasprobably in 1857, when Otis placed one in a store on Broadway at BroomeStreet in New York.

In the decade following the Civil War, tall buildings had just begun toemerge; and, although the skylines of the world’s great cities were stilldominated by church spires, there was increasing activity in thedevelopment of elevator apparatus adapted to the transportation of peopleas well as of merchandise. Operators of hotels and stores gradually becameaware of the commercial advantages to be gained by elevating their patronseven one or two floors above the ground, by machinery. The steam engineformed the foundation of the early elevator industry, but as buildingheights increased it was gradually replaced by hydraulic, and ultimatelyby electrical, systems.

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THE STEAM ELEVATOR

The progression from an elevator machine powered by the line shafting of amill to one in which the power source was independent would appear asimple and direct one. Nevertheless, it was about 40 years after theintroduction of the powered elevator before it became common to coupleelevator machines directly to separate engines. The multiple belt andpulley transmission system was at first retained, but it soon becameevident that a more satisfactory service resulted from stopping andreversing the engine itself, using a single fixed belt to connect theengine and winding mechanism. Interestingly, the same pattern was followed40 years later when the first attempts were made to apply the electricmotor to elevator drive.

Figure 8.—In the typical steam elevator machine twovertical cylinders
were situated either above or below the crankshaft, anda small pulley
was keyed to the crankshaft. In a light-duty machine, thepower was
transmitted by flatbelt from the small pulley to a larger onemounted
directly on the drum. In heavy-duty machines, spur gearing was
interposed between the large secondary pulley and the winding drum.
(Photo courtesy of Otis Elevator Company.)

Figure 9.—Several manufacturers built steam machines inwhich a gear
on the drum shaft meshed directly with a worm on thecrankshaft. This
arrangement eliminated the belt, and, since the drumcould not drive the
engine through the worm gearing, no brake wasnecessary for holding the load.
(Courtesy of Otis Elevator Company.)

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Figure 10.—Components of the
steam passenger elevator atthe time of its peak
development and use (1876).
(From The First OneHundred Years,
Otis Elevator Company, 1953.)

By 1870 the steam elevator machine had attained its ultimate form, which,except for a number of minor refinements, was to remain unchanged untilthe type became completely obsolete toward the end of the century.

By the last quarter of the century, a continuous series of improvements inthe valving, control systems, and safety features of the steam machine hadmade possible an elevator able to compete with the subsequently appearinghydraulic systems for freight and low-rise passenger service insofar assmoothness, control, and lifting power were concerned. However, steammachinery began to fail in this competition as the increasing height ofbuildings rapidly extended the demands of speed and length of rise.

The limitation in rise constituted the most serious shortcoming of thesteam elevator (figs. 8-10), an inherent defect that did not exist in thevarious hydraulic systems.

Since the only practical way in which the power of a steam engine could beapplied to the haulage of elevator cables was through a rotational system,the[Pg 10] cables invariably were wound on a drum. The travel or rise of the carwas therefore limited by the cable capacity of the winding drum. Asbuilding heights increased, drums became necessarily longer and largeruntil they grew so cumbersome as to impose a serious limitation uponfurther upward growth. A drum machine rarely could be used for a lift ofmore than 150 feet.[5]

Another organic difficulty existing in drum machines was the dangerouspossibility of the car—or the counterweight, whose cables often wound onthe drum—being drawn past the normal top limit and into the uppersupporting works. Only safety stops could prevent such an occurrence ifthe operator failed to stop the car at the top or bottom of the shaft, andeven these were not always effective. Hydraulic machines were notsusceptible to this danger, the piston or plunger being arrested by theends of the cylinder at the extremes of travel.

THE HYDRAULIC ELEVATOR

The rope-geared hydraulic elevator, which was eventually to become knownas the “standard of the industry,” is generally thought to have evolveddirectly from an invention of the English engineer Sir William Armstrong(1810-1900) of ordnance fame. In 1846 he developed a water-powered crane,utilizing the hydraulic head available from a reservoir on a hill 200 feetabove.

The system was not basically different from the simple hydraulic press sowell known at the time. Water, admitted to a horizontal cylinder,displaced a piston and rod to which a sheave was attached. Around thesheave passed a loop of chain, one end of which was fixed, the otherrunning over guide sheaves and terminating at the crane arm with a liftinghook. As the piston was pressed into the cylinder, the free end of thechain was drawn up at triple the piston speed, raising the load. Theeffect was simply that [Pg 11]of a 3-to-1 tackle, with the effort and loadelements reversed. Simple valves controlled admission and exhaust of thewater. (See fig. 11.)

Figure 11.—Armstrong’s hydraulic crane. The main cylinderwas inclined, permitting gravity to assist in overhauling the hook.
Thesmall cylinder rotated the crane. (From John H. Jallings, Elevators, Chicago, 1916, p. 82.)

The success of this system initiated a sizable industry in England, andthe hydraulic crane, with many modifications, was in common use there formany years. Such cranes were introduced in the United States in about 1867but never became popular; they did, however, have a profound influence onthe elevator art, forming the basis of the third generic type to achievewidespread use in this country.

The ease of translation from the Armstrong crane to an elevator systemcould hardly have been more evident, only two alterations of consequencebeing necessary in the passage. A guided platform or car was substitutedfor the hook; and the control valves were connected to a stationaryendless rope that was accessible to an operator on the car.

The rope-geared hydraulic system (fig. 13) appeared in mature form inabout 1876. However, before it had become the “standard elevator” througha process of refinement, another system was introduced which merits noticeif for no other reason than that its popularity for some years seemsremarkable in view of its preposterously unsafe design. Patented by CyrusW. Baldwin of Boston in January 1870, this system was termed theHydro-Atmospheric Elevator, but more commonly known as the water-balanceelevator (fig. 12). It employed water not under pressure but simply asmass under the influence of gravity. The elevator car’s supporting cablesran over sheaves at the top of the shaft to a large iron bucket, whichtraveled in a closed tube or well adjacent to and the same length as theshaft. To raise the car, the operator caused a valve to open, filling thebucket with water from a roof tank. When the weight of water wassufficient to overbalance the loaded car, the bucket descended, raisingthe car. On its ascent the car was stopped at intermediate floors by astrong brake that gripped the guides. Upon reaching the top, the operatorwas able to open a valve in the bucket, now at the bottom of its travel,and discharge its contents into a basem*nt tank, to be pumped back to theroof. No longer counterbalanced, the car could descend, its speedcontrolled solely by the brake.

The great popularity of this novel system apparently was due to its smoothoperation, high speed, simplicity, and economy of operation. Managed by askillful[Pg 12] operator, it was capable of speeds far greater than othersystems could then achieve—up to a frightening 1,800 feet per minute.[6]

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Figure 12.—Final development of the
Baldwin-Hale water balance elevator, 1873.
The brake, kept applied by powerful springs,
was released only by steady pressure on a lever.
There were two additional controls—the
continuous rope that opened the cistern valve to fill
the bucket, and a second lever to open the
valve of the bucket to empty it. (From
United States Railroad and Mining Register,
Apr. 12, 1873, vol. 17, p. 3.)

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Figure 13.—Vertical cylinder,
rope-geared hydraulic elevator with 2:1
gear ratio and rope control (about 1880).
For higher rises and speeds, ratios of
up to 10:1 were used, and the endless rope
was replaced by a lever.
(Courtesy of Otis Elevator Company.)

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

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

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

The rope-geared system of hydraulic elevator operation was so basicallysimple that by 1880 it had been embraced by virtually all manufacturers.However, for years most builders continued to maintain a line of steam andbelt driven machines for freight service. Inspired by the rapid increaseof 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. Itwas safe. Absence of a drum enabled the car to be carried by a number ofcables rather than by one or two, and rendered overtravel impossible. Itwas fast. Control devices had received probably the most attention byengineers and were as perfect and sensitive as was [Pg 13]possible withmechanical means. Cars with lever control could be run at the high speedsrequired for high buildings, yet they could be stopped with a smoothnessand precision unattainable earlier with systems in which the valves werecontrolled by an endless rope, worked by the operator. It was almostcompletely silent, and when the cylinder was placed vertically in a wellnear the shaft, practically no valuable floor space was occupied. But mostimportant, the length of rise was unlimited because no drum was used. Asgreater rises were required, the multiplication of the ropes and sheaveswas simply increased, raising the piston-car travel ratio and permittingthe cylinder to remain of manageable length. The ratio was often as highas 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 beoperated directly from municipal water mains in the many cities wherethere was sufficient pressure, thus eliminating a large investment intanks, pumps and boilers (fig. 14).

By far the greatest development in this specialized branch of mechanicalengineering occurred in the United States. The comparative position ofAmerican practice, which will be demonstrated farther on, is indicated bythe fact that Otis Brothers and other large elevator concerns in theUnited States were able to establish offices in many of the major citiesof Europe and compete very successfully with local firms in spite of thehigher costs due to shipment. This also demonstrates the extent of errorin the oft-heard statement that the skyscraper was the direct result ofthe elevator’s invention. There is no question that continued elevatorimprovement was an essential factor in the rapid increase of buildingheights. However, consideration of the situation in European cities, wherebuildings of over 10 stories were (and still are) rare in spite of theavailability of similar elevator techniques, points to the fundamentalmatter of tradition. The European city simply did not develop with thelack of judicial restraint which characterized metropolitan growth in theUnited States. The American tendency to confine mercantile activity to thesmallest possible area resulted in excessive land values, which drovebuildings skyward.[Pg 14] The elevator followed, or, at most, kept pace with,the development of higher buildings.

Figure 14.—In the various hydraulic systems, a pump was required if
pressure from water mains was insufficient to operate the elevator directly.
There was either a gravity tank on the roof or a pressure tank in the basem*nt.
(From Thomas E. Brown, Jr., “The American Passenger Elevator,”
Engineering Magazine (New York), June 1893, vol. 5, p. 340.)

European elevator development—notwithstanding the number of Americanrope-geared hydraulic machines sold in Europe in the 10 years or sopreceding the Paris fair of 1889—was confined mainly to variations on thedirect plunger type, which was first used in English factories in the1830’s. The plunger elevator (fig. 16), an even closer derivative of thehydraulic press Armstrong’s crane, was nothing more than a platformon the upper end of a vertical plunger that rose from a cylinder as waterwas forced in.

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

THE ELECTRIC ELEVATOR

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

The first application of electricity to elevator propulsion was anexperiment of the distinguished German electrician Werner von Siemens,who, in 1880, constructed a car that successfully climbed a rack by meansof a motor and worm gearing beneath its deck (figs. 17, 18)—again, thecharacteristic European distrust of cable suspension. However, the effectof this success on subsequent development was negligible. Significant useof electricity in this field occurred somewhat later, and in a mannerparallel to that by which steam was first applied to the elevator—thedriving of mechanical (belt driven) elevator machines by individualmotors. 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 pumpswere necessary in cases where water main pressure was insufficient tooperate the elevator directly.

In both of these cases the operational demands on the motor were of courseidentical to those on the prime movers which they replaced; no reversal ofdirection was necessary, the speed was constant, and the load was nearlyconstant. Furthermore, the load could be applied to the motor graduallythrough automatic relief valves on the pump and in the mechanical machinesby slippage as the belt was shifted from the loose to the fast pulleys.The ultimate simplicity in control resulted from permitting the motor torun continuously, drawing current only in proportion to its loading. Thedirect-current motor of the 1880’s was easily capable of such service, andit was widely used in this way.

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Figure 15.—Rope-geared hydraulic freight elevator
using a horizontal cylinder (about 1883).
(From a Lane & Bodley illustrated catalog of hydraulic elevators, Cincinnati, n.d.)

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Larger Image Figure 16.—English direct plunger hydraulic elevator (about 1895). (From F. Dye, Popular Engineering, London, 1895, p. 280.)

Adaptation of the motor to the direct drive of an elevator machine wasquite another matter, the difficulties being largely those of control. Atthis time the only practical means of starting a motor under load was byintroducing resistance into the circuit and cutting it out in a series ofsteps as the speed picked up; precisely the method used to start tractionmotors. In the early attempts to couple the motor directly to the windingdrum through worm gearing, this “notching up” was transmitted to the caras a jerking motion, disagreeable to passengers and hard on machinery.Furthermore, the controller contacts had a short life because of thearcing which resulted from heavy starting currents. In all, such systemswere unsatisfactory and generally unreliable, and were held in disfavor byboth elevator experts and owners.

Larger Image Figure 17.—Siemens’ electric rack-climbing elevator of 1880. (From Werner von Siemens, Gesammelte Abhandlungen und Vorträge, Berlin, 1881, pl. 5.)

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Figure 18.—Motor and drive mechanism
of Siemens’ elevator.
(From Alfred R. Urbanitzky,
Electricity in the Service of Man,
London, 1886, p. 646.)

There was, moreover, little inducement to overcome the problem of controland other minor problems because of a more serious difficulty which hadpersisted since the days of steam. This was the matter of the drum and itsattendant limitations. The motor’s action being rotatory, the winding drumwas the only practical way in which to apply its motive power to hoisting.This single fact shut electricity almost completely out of any large-scaleelevator business until after the turn of the century. True, there was acertain amount of development, after about 1887, of the electricworm-drive drum machine for slow-speed, low-rise service (fig. 19). Butthe first installation of this type that was considered practicallysuccessful—in that it was in continuous use for a long period—was notmade until 1889,[7] the year in which the Eiffel Tower was completed.

Pertinent is the one nearly successful attempt which was made to approachthe high-rise problem electrically. In 1888, Charles R. Pratt, an elevatorengineer of Montclair, New Jersey, invented a machine based on thehorizontal cylinder rope-geared hydraulic elevator, in which the two setsof sheaves were drawn apart by a screw and traveling nut. The screw wasrevolved directly by a Sprague motor, the system being known as theSprague-Pratt. While a number of installations were made, the machine wassubject to several serious mechanical faults and passed out of use around1900. Generally, electricity as a practical workable power for elevatorsseemed to hold little promise in 1888.[8]

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Figure 19.—The electric elevator in its earliest commercial form (1891),
with the motor connected directly to the load. By this time, incandescent
lighting circuits in large cities were sufficiently extensive to make such
installations practical. However, capacity and lift were severely limited by
weaknesses of the control system and the necessity of using a drum.
(From Electrical World, Jan. 2, 1897, vol. 20, p. xcvii.)
Image Text

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Figure 20.—Advertisem*nt for the Miller screw-hoisting machine, about1867 (see p. 23).
From flyer in the United States National Museum.
Image Text

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Figure 21.—The first widespread use of electricity in theelevator field was to drive
belt-type mechanical machines and the pumps ofhydraulic systems (see p. 14) as shown here.
(From Electrical World, Jan. 4, 1890, vol. 15, p. 4.)

The Tower’s Elevators

A great part of the Eiffel Tower’s worth and its raison d’être lay inthe overwhelming visual power by which it was to symbolize to a worldaudience the scientific, artistic, and, above all, the technicalachievements of the French Republic. Another consideration, in Eiffel’sopinion, was its great potential value as a scientific observatory. At itssummit grand experiments and observations would be possible in such fieldsas meteorology and astronomy. In this respect it was welcomed as atremendous improvement over the balloon and steam winch that had beenfeatured in this service at the 1878 Paris exposition. Experiments werealso to be conducted on the electrical illumination of cities from greatheights. The great strategic value of the Tower as an observation postalso was recognized. But from the beginning, sight was never lost of thestructure’s great value as an unprecedented public attraction, and itssystematic exploitation in this manner played a part in its planning,second perhaps only to the basic design.

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Figure 22.—Various levels of the Eiffel Tower.
(Adapted from Gustave Eiffel,
La Tour de Trois Cents Mètres,
Paris, 1900, pl. 1.)

The conveyance of multitudes of visitors to the Tower’s first or mainplatform and a somewhat lesser number to the summit was a technicalproblem whose seriousness Eiffel must certainly have been aware of at theproject’s onset. While a few visitors could be expected to walk to thefirst or possibly second stage, 377 feet above the ground, the main meansof transport obviously had to be elevators. Indeed, the two aspects of theTower with which the Exposition commissioners were most deeply concernedwere the adequate grounding of lightning and the provision of a reliablesystem of elevators, which they insisted be unconditionally safe.

To study the elevator problem, Eiffel retained a man named Backmann whowas considered an expert on the subject. Apparently Backmann originallywas to design the complete system, but he was to prove inadequate to thetask. As his few schemes are[Pg 21] studied it becomes increasingly difficult toimagine by what qualifications he was regarded as either an elevatorexpert or designer by Eiffel and the Commission. His proposals appear,with one exception, to have been decidedly retrogressive, and, further, toincorporate the most undesirable features of those earlier systems hechose to borrow from. Nothing has been discovered regarding his work, ifany, on elevators for the lower section of the Tower. Realizing thedifficulty of this aspect of the problem, he may not have attempted itssolution, and confined his work to the upper half where the structurepermitted a straight, vertical run.

The Backmann design for the upper elevators was based upon a principlewhich had been attractive to many inventors in the mid-19th century periodof elevator development—that of “screwing the car up” by means of athreaded element and a nut, either of which might be rotated and the otherremain stationary. The analogy to a nut and bolt made the scheme anobvious one at that early time, but its inherent complexity soon becameequally evident and it never achieved practical success. Backmannprojected two cylindrical cars that traveled in parallel shafts andbalanced one another from opposite ends of common cables that passed overa sheave in the upperworks. Around the inside of each shaft extended aspiral track upon which ran rollers attached to revolving framesunderneath the cars. When the frames were made to revolve, the rollers,running around the track, would raise or lower one car, the othertraveling in the opposite direction (fig. 23).

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

[Pg 22]

Figure 23.—Backmann’s proposed helicoidal elevator for theupper section of the Eiffel Tower.
The cars were to be self-powered byelectric motors. Note similarity to the Miller system (fig. 20).
(Adaptedfrom The Engineer (London), Aug. 3, 1888, vol. 66, p. 101.)

[Pg 23]Backmann’s second proposal, actually approved by the Commission,incorporated the only—although highly significant—innovation evident inhis designs. For the rope transmission, electric motors were substituted,one in each car to drive the roller frame directly. With thismodification, the plan does not seem quite as unreasonable, and wouldprobably have worked. However, it would certainly have lacked thenecessary durability and would have been extremely expensive. TheCommission discarded the whole scheme about the middle of 1888, giving tworeasons for its action: (1) the novelty of the system and the attendantpossibility of stoppages which might seriously interrupt the “exploitationof the Tower,” and (2) fear that the rollers running around the trackswould cause excessive noise and vibration. Both reasons seem quiteincredible when the Backmann system is compared to one of those actuallyused—the Roux, described below—which obviously must have been subject toidentical failings, and on a far greater scale. More likely there existedan unspoken distrust of electric propulsion.

That the Backmann system should have been given serious consideration atall reflects the uncertainty surrounding the entire matter of providingelevator service of such unusual nature. Had the Eiffel Tower been erectedonly 15 years later, the situation would have been simply one ofselection. As it was, Eiffel and the commissioners were governed not bywhat they wanted but largely by what was available.

THE OTIS SYSTEM

The curvature of the Tower’s legs imposed a problem unique in elevatordesign, and it caused great annoyance to Eiffel, the fair’s Commission,and all others concerned. Since a vertical shaftway anywhere within theopen area beneath the first platform was esthetically unthinkable, theelevators could be placed only in the inclined legs. The problem ofreaching the first platform was not serious. The legs were wide enough andtheir curvature so slight in this lower portion as to permit them tocontain a straight run of track, and the service could have been designedalong the lines of an ordinary inclined railway. It was estimated that thegreat majority of visitors would go only to this level, attracted by theseveral international restaurants, bars and other features located there.Two elevators to operate only that far were contracted for with nodifficulty—one to be placed in the east leg and one in the west.

To transport people to the second platform was an altogether differentproblem. Since there was to be a single run from the ground, it would havebeen necessary to form the elevator guides either with a constantcurvature, approximating that of the legs, or with a series of straightchords connected by short segmental curves of small radius. Eiffel plannedinitially to use the first method, but the second was adopted ultimately,probably as being the simpler because only two straight lengths of runwere found to be necessary.

Bids were invited for two elevators on this basis—one each for the northand south legs. Here the unprecedented character of the matter becameevident—there was not a firm in France willing to undertake the work. TheAmerican Elevator Company, the European branch of Otis Brothers & Company,did submit a proposal through its Paris office, Otis Ascenseur Cie., butthe Commission was compelled to reject it because a clause in the fair’scharter prohibited the use of any foreign material in the construction ofthe Tower. Furthermore, there was a strong prejudice against foreigncontractors, which, because of the general background of disfavorsurrounding the project during its early stages, was an element worthserious consideration by the Commission. The bidding time was extended,and many attempts were made to attract a native design but none wasforthcoming.

Larger Image
Figure 24.—General arrangement of
Otis elevator system inEiffel Tower.
(From The Engineer (London),
July 19, 1889, vol. 68, p. 58.)

[Pg 24]As time grew short, it became imperative to resolve the matter, and theCommission, in desperation, awarded the contract to Otis in July 1887 forthe amount of $22,500.[10] A curious footnote to the affair appeared muchlater in the form of a published interview[11] with W. Frank Hall, Otis’Paris representative:

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

The proposed system (fig. 24) was based fundamentally upon Otis’ standardhydraulic elevator, but it was recognizable only in basic operatingprinciple (fig. 25). Tracks of regular rail section replaced the guidesbecause of the incline, and the double-decked cabin (fig. 29) ran on smallflanged wheels. This much of the apparatus was really not unlike that ofan ordinary inclined railway. Motive power was provided by the customaryhydraulic cylinder (fig. 26), set on an angle roughly equal to the inclineof the lower section of run. Balancing the cabin’s dead weight was acounterpoise carriage (fig. 27) loaded with pig iron that traveled on asecond set of rails beneath the main track. Like the driving system, thecounterweight was rope-geared, 3 to 1, so that its travel was about 125feet to the cabin’s 377 feet.

Everything about the system was on a scale far heavier than found in thenormal elevator of the type. The cylinder, of 38-inch bore, was 36 feetlong. Rather than a simple nest of pulleys, the piston rods pulled a largeguided carriage or “chariot” bearing six movable sheaves (fig. 28).Corresponding were five stationary sheaves, the whole reeved to form animmense 12-purchase tackle. The car, attached to the free ends of thecables, was hauled up as the piston drew the two sheave assemblies apart.

[Pg 25]

Figure 25.—Schematic diagram of the rigging of the Otissystem.
(Adapted from Gustave Eiffel, La Tour de Trois Cents Mètres, Paris, 1900, p. 127.)

In examining the system, it is difficult to determine what single elementin its design might have caused such a problem as to have been beyond theengineering ability of a French firm, and to have caused such concern to alarge, well-established American organization of Otis’ wide elevator andinclined railway experience. Indeed, when the French system—which servedthe first platform from the east and west legs—is examined, it appearscurious that a national technology capable of producing a machine at sucha level of complexity should have been unable to deal easily with theentire matter. This can be plausibly explained only on the basis ofEurope’s previously mentioned lack of experience with rope-geared andother cable-hung elevator systems. The difficulty attending Otis’ work,usually true in the case of all innovations, lay unquestionably in themultitudes of details—many of them, of course, invisible when only thesuccessfully working end product is observed.

More than a matter of detail was the Commission’s demand for perfectsafety, which precipitated a situation typical of many confronting Otisduring the entire work. Otis had wished to coordinate the entire designprocess through Mr. Hall, with technical matters handled by mail.Nevertheless, at Eiffel’s insistence, and with some inconvenience, in 1888the company dispatched the project’s engineer, Thomas E. Brown, Jr., toParis for a direct consultation. Mild conflict over minor details ensued,but a gross difference of opinion arose ultimately between the Americanand French engineers over the safety of the system. The disagreementthreatened to halt the entire project. In common with all elevators inwhich the car hangs by cables, the prime consideration here was a means ofarresting the cabin should the cables fail. As originally presented toEiffel, the plans indicated an elaborate modification of the standard Otissafety device—itself a direct derivative of E. G. Otis’ original.

If any one of the six hoisting cables broke or stretched unduly, or iftheir tension slackened for any reason, powerful leaf springs werereleased causing brake shoes to grip the rails. The essential feature ofthe design was the car’s arrest by friction between its grippers and therails so that the stopping action was gradual, not sudden as in theelevator safety. During proof trials of the safety, made prior to thefair’s opening by cutting away a set of temporary hoisting cables, thecabin would fall about 10 feet before being halted.

[Pg 26]

Figure 26.—Section through the Otis power cylinder.
(Adapted from Gustave Eiffel, La Tour de Trois Cents Mètres, Paris, 1900, pl. 22.)

[Pg 27]

Figure 27.—Details of the counterweight carriage in the Otis system.
(From Gustave Eiffel, La Tour de Trois Cents Mètres, Paris, 1900, pl. 22⁴.)

Although highly efficient and of unquestionable security, this safetydevice was considered an insufficient safeguard by Eiffel, who, speakingin the name of the Commission, demanded the application of a device knownas the rack and pinion safety that was used to some extent on European cograilways. The commissioners not only considered this system more reliablebut felt that one of its features was a necessity: a device thatpermitted the car to be lowered by hand, even after failure of all thehoisting cables. The serious shortcomings of the rack and pinion were itsgreat noisiness and the limitation it imposed on hoisting speed. Bothdisadvantages were due to the constant engagement of a pinion on the carwith a continuous rack set between the rails. The meeting ended in animpasse, with Brown unwilling to approve the objectionable apparatus andable only to return to New York and lay the matter before his company.

While Eiffel’s attitude in the matter may appear highly unreasonable, itmust be said that during a subsequent meeting between Brown andKœchlin, the French engineer implied that a mutual antagonism hadarisen between the Tower’s creator and the Commission. Thus, since his ownjudgment must have had little influence with the commissioners at thattime, Eiffel was compelled to specify what he well knew were excessivesafety provisions.

This decision placed Otis Brothers in a decidedly uncomfortable position,at the mercy of the Commission. W. E. Hale, promoter of the water balanceelevator—who by then had a strong voice in Otis’ affairs—expressed theseriousness of the matter in a letter to the company’s president, CharlesR. Otis, following receipt of Brown’s report on the Paris conference.Referring to the controversial cogwheel, Hale wrote

... if this must be arranged so that the car is effected [sic] in itsoperation by constant contact with the rack and pinion ... so as tocommunicate the noise and jar, and unpleasant motion which such anarrangement always produces, I should favor giving up the wholematter rather than allying ourselves with any such abortion.... wewould be the laughing stock of the world, for putting up such acontrivance.

This difficult situation apparently was the product of a somewhat generalcontract phrased in terms of service to be provided rather than ofspecific equipment to be used. This is not unusual, but it did leave opento later dispute such ambiguous clauses as “adequate safety devices are tobe provided.”

Although faced with the loss not only of all previously expended designwork but also of an advertisem*nt of international consequence, thecompany apparently concurred with Hale and so advised Paris.Unfortunately, there are no Otis records to reveal the subsequenttransactions, but we may assume that Otis’ threat of withdrawal prevailed,coupled as it was with Eiffel’s confidence in the American equipment. Thesystem went into operation as originally designed, free of the odious rackand pinion.

That, unfortunately, was not the final disagreement. Before the fair’sopening in May 1889, the relationship was strained so drastically that amutually satisfactory conclusion to the project must indeed have seemedhopeless. The numerous minor structural modifications of the Tower legsfound necessary as construction progressed had necessitated certainequivalent alteration to the Otis design insofar as its dependency upon[Pg 28]the framework was affected. Consequently, work on the machinery was setback by some months. Eiffel was informed that although everything wasguaranteed to be in full operation by opening day on May 1, thecontractual deadline of January 1 could not possibly be met. Eiffel, nowunquestionably acting on his own volition, responded by cable, refusingall payment. Charles Otis’ reply, a classic of indignation, disclosed toEiffel the jeopardy in which his impetuosity had placed the success of theentire project:

After all else we have borne and suffered and achieved in yourbehalf, we regard this as a trifle too much; and we do not hesitateto declare, in the strongest terms possible to the English language,that we will not put up with it ... and, if there is to be War, underthe existing circ*mstances, propose that at least part of it shall befought on American ground. If Mr. Eiffel shall, on the contrary,treat us as we believe we are entitled to be treated, under thecirc*mstances, and his confidence in our integrity to serve him wellshall be restored in season to admit of the completion of this workat the time wanted, well and good; but it must be done at once ...otherwise we shall ship no more work from this side, and Mr. Eiffelmust charge to himself the consequences of his own acts.

This message apparently had the desired effect and the matter was somehowresolved, as the machinery was in full operation when the Expositionopened. The installation must have had immense promotional value for OtisBrothers, particularly in its contrast to the somewhat anomalous Frenchsystem. This contrast evidently was visible to the technicallyunsophisticated as well as to visiting engineers. Several newspapersreported that the Otis elevators were one of the best American exhibits atthe fair.

In spite of their large over-all scale and the complication of the basicpattern imposed by the unique situation, the Otis elevators performed welland justified the original judgment and confidence which had promptedEiffel to fight for their installation. Aside from the obvious advantageof simplicity when compared to the French machines, their operation wasrelatively quiet, and fast.

The double car, traveling at 400 feet per minute, carried 40 persons, allseated because of the change of inclination. The main valve or distributorthat controlled the flow of water to and from the driving cylinder wasoperated from the car by cables. The hydraulic head necessary to producepressure within the cylinder was obtained from a large open reservoir onthe second platform. After being exhausted from the cylinder, the waterwas pumped back up by two Girard pumps (fig. 31) in the engine room atthe base of the Tower’s south leg.

THE SYSTEM OF ROUX, COMBALUZIER AND LEPAPE

There can be little doubt that the French elevators placed in the east andwest piers to carry visitors to the first stage of the Tower had theimportant secondary function of saving face. That an engineer of Eiffel’smechanical perception would have permitted their use, unless compelled todo so by the Exposition Commission, is unthinkable. Whatever the attitudesof the commissioners may have been, it must be said—recalling theBackmann system—that they did not fear innovation. The machineryinstalled by the firm of Roux, Combaluzier and Lepape was novel in everyrespect, but it was a product of misguided ingenuity and set no precedent.The system, never duplicated, was conceived, born, lived a brief and notoverly creditable life, and died, entirely within the Tower.

Basis of the French system was an endless chain of short, rigid,articulated links (fig. 35), to one point of which the car was attached.As the chain moved, the car was raised or lowered. Recalling the Europeandistrust of suspended elevators, it is interesting to note that the carwas pushed up by the links below, not drawn by those above, thus theactive links were in compression. To prevent buckling of the column, thechain was enclosed in a conduit (fig. 36). Excessive friction wasprevented by a pair of small rollers at each of the knuckle joints betweenthe links. The system was, in fact, a duplicate one, with a chain oneither side of the car. At the bottom of the run the chains passed aroundhuge sprocket wheels, 12.80 feet in diameter, with pockets on theirperipheries to engage the joints. Smaller wheels at the top guided thechains.

If by some motive force the wheel (fig. 33) were turned counterclockwise,the lower half of the chain would be driven upward, carrying the car withit. Slots on the inside faces of the lower guide trunks permitted passageof the connection between the car and chain. Lead weights on certain linksof the chains’ upper or return sections counterbalanced most of the car’sdead weight.

[Pg 29]

Figure 28.—Plan and section of the Otis system’s movablepulley assembly, or chariot. Piston rods are at left.
(Adapted from TheEngineer (London), July 19, 1889, vol. 68, p. 58.)

Two horizontal cylinders rotated the driving sprockets through a mechanismwhose effect was similar to the rope-gearing of the standard hydraulicelevator, but which might be described as chain gearing. The cylinderswere of the pushing rather than the pulling type used in the Otis system;that is, the pressure was introduced behind the plungers, driving themout. To the ends of the plungers were fixed smooth-faced sheaves, overwhich were looped heavy quadruple-link pitch chains, one end of each beingsolidly attached to the machine base. The free ends ran under the cylinderand made another half-wrap around small sprockets keyed to the main driveshaft. As the plungers were forced outward, the free ends of the chainmoved in the opposite direction, at twice the velocity and lineardisplacement of the plungers. The drive sprockets were thereby revolved,driving up the car. Descent was made simply by permitting the cylinders toexhaust, the car dropping of its own weight. The over-all gear or ratio ofthe system was the multiplication due to the double purchase of theplunger sheaves times the ratio of the chain and drive sprocket diameters:2(12.80/1.97) or about 13:1. To drive the car 218 feet to the firstplatform of the Tower the plungers traveled only about 16.5 feet.

To penetrate the inventive rationale behind this strange machine is notdifficult. Aware of the fundamental dictum of absolute safety before allelse, the Roux engineers turned logically to the safest known elevatortype—the direct plunger. This type of elevator, being well suited to lowrises, formed the main body of European practice at the time, and in thisfact lay the further attraction of a system firmly based on tradition.Since the piers between the ground and first platform could accommodate astraight, although inclined run, the solution might obviously have been touse an inclined, direct plunger. The only difficulty would have been thatof drilling a 220-foot, inclined well for the cylinder. While a difficultproblem, it would not have been insurmountable. What then was the reasonfor using a design vastly more complex? The only reasonable answer thatpresents itself is that the designers, working[Pg 30] in a period before theOtis bid had been accepted, were attempting to evolve an apparatus capableof the complete service to the second platform. The use of a rigid directplunger thus precluded, it became necessary to transpose the basic idea inorder to adapt it to the curvature of the Tower leg, and at the same timeretain its inherent quality of safety. Continuing the conceptual sequence,the idea of a plunger made in some manner flexible apparently suggesteditself, becoming the heart of the Roux machines.

Figure 29.—Section through cabin of the Otis elevator.Note the pivoted floor-sections.
As the car traveled, these floor-sectionswere leveled by the operator to compensate
for the change of inclination;however, they were soon removed because they interfered
with the loadingand unloading of passengers. (From La Nature, May 4, 1889, vol. 17, p. 360.)

Here then was a design exhibiting strange contrast. It was on the one handcompletely novel, devised expressly for this trying service; yet on theother hand it was derived from and fundamentally based on a thoroughlytraditional system. If nothing else, it was safe beyond question. InEiffel’s own words, the Roux lifts “not only were safe, but appearedsafe; a most desirable feature in lifts traveling to such heights andcarrying the general public.”[12]

The system’s shortcomings could hardly be more evident. Friction resultingfrom the more than 320 joints in the flexible pistons, each carrying tworollers, plus that from the pitch chains must have been immense. The noisecreated by such multiplicity of parts can only be imagined. Capacity wasequivalent to that of the Otis system. About 100 people could be carriedin the double-deck cabin, some standing. The speed, however, was only 200feet per minute, understandably low.

If it had been the initial intention of the designers to operate theircars to the second platform, they must shortly have become aware of theimpracticability of this plan, caused by an inherent characteristic of theapparatus. As long as the compressive force acted along the longitudinalaxis of the links, there was no lateral resultant and the only load on thesmall rollers was that due to the dead weight of the link itself. However,if a curve had been introduced in the guide channels to increase theincline of the upper run, as done by Otis, the force on those linkstraversing the bend would have been eccentric—assuming the car to be inthe upper section, above the bend. The difference between the two sections(based upon the Otis system) was 78°9′ minus 54°35′, or 23°34′, thetangent of which equals 0.436. Forty-three percent of the unbalancedweight of the car and load would then have borne upon the, say, 12 sets ofrollers on the curve. The immense frictional load thus added to the entiresystem would certainly have made it dismally inefficient, if not actuallyunworkable.

In spite of Eiffel’s public remarks regarding the safety of the Rouxmachinery, in private he did not trouble to conceal his doubts. Otis’representative, Hall, discussing this toward the end of Brown’s previouslymentioned report, probably presented a fairly accurate picture of thesituation. His comments were based on conversations with Eiffel andKœchlin:

Mr. Gibson, Mr. Hanning [who were other Otis employees] and myselfcame to the unanimous conclusion that Mr. Eiffel had been forced toorder those other machines, from outside parties, against his ownjudgment: and that he was very much in doubt as to their being apractical success—and was, therefore, all the more anxious to put inour machines[Pg 31] (which he did have faith in) ... and if the others ateup coal in proportions greatly in excess of ours, he would have it tosay ... “Gentlemen, these are my choice of elevators, those are yours&c.” There was a published interview ... in which Eiffel stated ...that he was to meet some American gentlemen the following day, whowere to provide him with elevators—grand elevators, I think hesaid....

Figure 30.—Upperworks and passenger platforms of the Otissystem at second level.
(From La Nature, Aug. 10, 1889, vol. 17, p. 169.)

The Roux and the Otis systems both drew their water supply from the sametanks; also, each system used similar distributing valves (fig. 32)operated from the cars. Although no reports have been found of actualcontrolled tests comparing the efficiencies of the Otis and Roux systems,a general quantitative comparison may be made from the balance figuresgiven for each (p. 40), where it is seen that 2,665 pounds of excesstractive effort were allowed to overcome the friction of the Otismachinery against 13,856 pounds for the Roux.

THE EDOUX SYSTEM

The section of the Tower presenting the least difficulty to elevatorinstallation was that above the juncture of the four legs—from the secondplatform to the third, or observation, enclosure. There was no questionthat French equipment could perform this service. The run being perfectlystraight and vertical, the only unusual demand upon contemporary elevatortechnology was the length of rise—525 feet.

The system ultimately selected (fig. 37) appealed to the Commissionlargely because of a one that had been installed in one tower ofthe famous Trocadero[13] and which had been operating successfully for 10years. It was the direct plunger system of Leon Edoux, and was, for thetime, far more rationally contrived than Backmann’s helicoidal system.Edoux, an old schoolmate of Eiffel’s, had built thousands of elevators inFrance and was possibly the country’s most successful inventor andmanufacturer in the field. It is likely that he did not attempt to obtainthe contract for the elevator equipment in the Tower legs, as hisexperience was based almost entirely on plunger systems, a type, as wehave seen, not readily adaptable to that situation. What is puzzling wasthe failure of the Commission’s members to recognize sooner Edoux’sobvious ability to provide equipment for the upper run. It may have beendue to their inexplicable confidence in Backmann.

[Pg 32]

Figure 31.—The French Girard pumps that supplied the Otisand Roux systems.
(From La Nature, Oct. 5, 1889, vol. 17, p. 292.)

The direct plunger elevator was the only type in which European practicewas in advance of American practice at this time. Not until the beginningof the 20th century, when hydraulic systems were forced into competitionwith electrical systems, was the direct plunger elevator improved inAmerica to the extent of being practically capable of high rises andspeeds. Another reason for its early disfavor in the United States was thenecessity for drilling an expensive plunger well equal in length to therise.[14]

As mentioned, the most serious problem confronting Edoux was the extremelyhigh rise of 525 feet. The Trocadero elevator, then the highest plungermachine in the world, traveled only about 230 feet. A secondarydifficulty was the esthetic undesirability of permitting a plungercylinder to project downward a distance equal to such a rise, which wouldhave carried it directly into the center of the open area beneath thefirst platform (fig. 6). Both problems were met by an ingeniousmodification of the basic system. The run was divided into two equalsections, each of 262 feet, and two cars were used. One operated from thebottom of the run at the second platform level to an intermediate platformhalf-way up, while the other operated from this point to the observationplatform near the top of the Tower. The two sections were of courseparallel, but offset. A central guide, on the Tower’s center-line, runningthe entire 525 feet served both cars, with shorter guides on eitherside—one for the upper and one for the lower run. Thus, each car traveledonly half the total distance. The two cars were connected, as in theBackmann system, by steel cables running over sheaves at the[Pg 33] top,balancing each other and eliminating the need for counterweights. Twodriving rams were used. By being placed beneath the upper car, theircylinders extended downward only the 262 feet to the second platform andso did not project beyond the confines of the system itself.[15] In makingthe upward or downward trip, the passengers had to change from one car tothe other at the intermediate platform, where the two met and parted (fig.39). This transfer was the only undesirable feature of what was, on thewhole, a thoroughly efficient and well designed work of elevatorengineering.

Figure 32.—The Otis distributor, with valves shown inmotionless, neutral position.
Since the main valve at all times wassubjected to the full operating pressure, it
was necessary to drive thisvalve with a servo piston. The control cable operated
only the servopiston’s valve. (Adapted from Gustave Eiffel, La Tour de Trois
Cents Mètres, Paris, 1900, p. 130.)

[Pg 34]

Figure 33.—General arrangement of the Roux Combaluzier and Lepape elevator.

[Pg 35]

Figure 34.—Roux, Combaluzier and Lepape machinery andcabin at the Tower’s base.
(From La Nature, Aug. 10, 1889, vol. 17, p. 168.)

In operation, water was admitted to the two cylinders from a tank on thethird platform. The resultant hydraulic head was sufficient to force outthe rams and raise the upper car. As the rams and car rose, the risingwater level in the cylinders caused a progressive reduction of theavailable head. This negative effect was further heightened by the factthat, as the rams moved upward, less and less of their length wasbuoyed by the water within the cylinders, increasing their effectiveweight. These two factors were, however, exactly compensated for by thelengthening of the cables on the other side of the pulleys as the lowercar descended. Perfect balance of the system’s dead load for any positionof the cabins was, therefore, a quality inherent in its design. However,there were two extreme conditions of live loading which requiredconsideration: the lower car full and the upper empty, or vice versa. Topermit the upper car to descend under the first condition, the plungerswere made sufficiently heavy, by the addition of cast iron at their lowerends, to overbalance the weight of a capacity load in the lower car. Thesecond condition demanded simply that the system be powerful enough tolift the unbalanced weight of the plungers plus the weight of passengersin the upper car.

As in the other systems, safety was a matter of prime importance. In thiscase, the element of risk lay in the possibility of the suspended carfalling. The upper car, resting on the rams, was virtually free of suchdanger. Here again the influence of Backmann was felt—a brake of hisdesign was applied (fig. 38). It was, true to form, a throwback, similarsafety devices having proven unsuccessful much earlier. Attached to thelower car were two helically threaded vertical[Pg 36] rollers, working withinthe hollow guides. Corresponding helical ribs in the guides rotated therollers as the car moved. If the car speed exceeded a set limit, theincreased resistance offered by the apparatus drove the rollers up intofriction cups, slowing or stopping the car.

Figure 35.—Detail of links in the Roux system. (FromGustave Eiffel, La Tour de Trois Cents Mètres, Paris, 1900, p. 156.)		Figure 36.—Section of guide trunks in the Roux system. (From Gustave Eiffel, La Tour de Trois Cents Mètres, Paris, 1900, p. 156.)

The device was considered ineffectual by Edoux and Eiffel, who were awarethat the ultimate safety of the system resulted from the use of supportingcables far heavier than necessary. There were four such cables, with atotal sectional area of 15.5 square inches. The total maximum load towhich the cables might be subjected was about 47,000 pounds, producing astress of about 3,000 pounds per square inch compared to a breaking stressof 140,000 pounds per square inch—a safety factor of 46![16]

[Pg 37]

Larger Image
Figure 37.—Schematic diagram of the Edoux system. (Adaptedfrom Gustave Eiffel, La Tour de Trois Cents Mètres, Paris, 1900, p. 175.)		Figure 38.—Vertical section through lower (suspended) Edoux car, showing Backmannhelicoidal safety brake. (Adapted from Gustave Eiffel, La Tour Eiffel en 1900, Paris, 1902, p. 12.)

A curiosity in connection with the Edoux system was the use of Worthington(American) pumps (fig. 40) to carry the water exhausted from the cylindersback to the supply tanks. No record has been found that might explain whythis particular exception was made to the “foreign materials” stipulation.This exception is even more strange in view of Otis’ futile request forthe same pumps and the fact that any number of native machines must havebeen available. It is possible that Edoux’s personal influence wassufficient to overcome the authority of the regulation.

[Pg 38]

Figure 39.—Passengers changing cars on Edoux elevator atintermediate platform.
(From La Nature, May 4, 1889, vol. 17, p. 361.)

Figure 40.—Worthington tandem compound steam pumps, atbase of the Tower’s south pier,
supplied water for the Edoux system. Thetank was at 896 feet, but suction was taken from
the top of the cylindersat 643 feet; therefore, the pumps worked against a head of only
about 250feet. (From La Nature, Oct. 5, 1889, vol. 17, p. 293.)

[Pg 39]

Figure 41.—Recent view of lower car of the Edoux system,
showing slotted cylindrical guides that enclose the cables.

Epilogue

In 1900, after the customary 11-year period, Paris again prepared for aninternational exposition, about 5 years too early to take advantage of thegreat progress made by the electric elevator. When the Roux machines, theweakest element in the Eiffel Tower system, were replaced at this time, itwas by other hydraulics. Built by the well known French engineeringorganization of Fives-Lilles, the new machines were the ultimate in power,control, and general excellence of operation. As in the Otis system, thecars ran all the way to the second platform.

The Fives-Lilles equipment reflected the advance of European elevatorengineering in this short time. The machines were rope-geared andincorporated the elegant feature of self-leveling cabins which compensatedfor the varying track inclination. For the 1900 fair, the Otis elevator inthe south pier was also removed and a wide stairway to the first platformbuilt in its place. In 1912, 25 years after Backmann’s startling proposalto use electricity for his system, the remaining Otis elevator wasreplaced by a small electric one. This innovation was reluctantlyintroduced solely for the purpose of accommodating visitors in the winterwhen the hydraulic systems were shut[Pg 40] down due to freezing weather. Theelectric elevator had a short life, being removed in 1922 when the numberof winter visitors increased far beyond its capacity. However, the twohydraulic systems were modified to operate in freezingtemperatures—presumably by the simple expedient of adding anantifreezing chemical to the water—and operation was placed on ayear-round basis.

Today the two Fives-Lilles hydraulic systems remain in full use; andvisitors reach the Tower’s summit by Edoux’s elevator (fig. 41), which isall that remains of the original installation.

Footnotes:

[1] Translated from Jean A. Keim, La Tour Eiffel, Paris, 1950.

[2] The foundation footings exerted a pressure on the earth of about 200pounds per square foot, roughly one-sixth that of the Washington Monument,then the highest structure in the world.

[3] A type of elevator known as the “teagle” was in use in some multistoryEnglish factories by about 1835. From its description, this elevatorappears to have been primarily for the use of passengers, but itunquestionably carried freight as well. The machine shown in figure 7 had,with the exception of a car safety, all the features of later systemsdriven from line shafting—counterweight, control from the car, andreversal by straight and crossed belts.

[4] The Otis safety, of which a modified form is still used, consistedessentially of a leaf wagon spring, on the car frame, kept strained by thetension of the hoisting cables. If these gave way, the spring, released,drove dogs into continuous racks on the vertical guides, holding the caror platform in place.

[5] A notable exception was the elevator in the Washington Monument.Installed in 1880 for raising materials during the structure’s finalperiod of erection and afterwards converted to passenger service, it wasfor many years the highest-rise elevator in the world (about 500 feet),and was certainly among the slowest, having a speed of 50 feet per minute.

[6] Today, although not limited by the machinery, speeds are set at amaximum of about 1,400 feet per minute. If higher speeds were used, animpractically long express run would be necessary for starting andstopping in order to prevent an acceleration so rapid as to beuncomfortable to passengers and a strain on the equipment.

[7] Two machines, by Otis, in the Demarest Building, Fifth Avenue and 33dStreet, New York. They were in use for over 30 years.

[8] Although the eventually successful application of electric power tothe elevator did not occur until 1904, and therefore goes beyond thechronological scope of this discussion, it was of such importance insofaras current practice is concerned as to be worthy of brief mention. In thatyear the first gearless traction machine was installed by Otis in aChicago theatre. As the name implies, the cables were not wrapped on adrum but passed, from the car, over a grooved sheave directly on the motorshaft, the other ends being attached to the counterweights. The result wasa system of beautiful simplicity, capable of any rise and speed with noproportionate increase in the number or size of its parts, and free fromany possibility of car or weights being drawn into the machinery. Thissystem is still the only one used for rises of over 100 feet or so. By thetime of its introduction, motor controls had been improved to the point ofcomplete practicability.

[9] Mechanical transmission of power by wire rope was a well developedpractice at this time, involving in many instances high powers anddistances up to a mile. To attempt this system in the Eiffel Tower,crowded with structural work, machinery and people, was another matter.

[10] According to Otis Elevator Company, the final price, because ofextras, was $30,000.

[11] In Pall Mall Gazette, as quoted in The Engineering and BuildingRecord and the Sanitary Engineer, May 25, 1889, vol. 19, p. 345.

[12] From speech at annual summer meeting of Institution of MechanicalEngineers, Paris, 1889. Quoted in Engineering, July 5, 1889, vol. 48, p. 18.

[13] Located near the Tower, built for the Paris fair of 1878.

[14] Improved oil-well drilling techniques were influential in the intensebut short burst of popularity enjoyed by direct plunger systems in theUnited States between 1899 and 1910. In New York, many such systems of200-foot rise, and one of 380 feet, were installed.

[15] An obvious question arises here: What prevents a plunger 200 or 300feet long and no more than 16 inches in diameter from buckling under itscompressive loading? The answer is simply that most of this length is notin compression but in tension. The Edoux rams, when fully extended,virtually hung from the upper car, sustained by the weight of 500 feet ofcable on the other side of the sheaves. As the upper car descended thiseffect diminished, but as the rams moved back into the cylinders theirunsupported length was correspondingly reduced.

[16] M. A. Ansaloni, “The Lifts in the Eiffel Tower,” quoted inEngineering, July 5, 1889, vol. 48, p. 23. The strength of steel whendrawn into wire is increased tremendously. Breaking stresses of 140,000p.s.i. were not particularly high at the time. Special cables withbreaking stresses of up to 370,000 p.s.i. were available.

Text figure 19

ELECTRIC ELEVATOR.

Write us for Circulars and Prices.

Main Office and Works, 1105 Frankford Avenue,
PHILADELPHIA.

Text figure 20

MILLER’S PATENT
LIFE AND LABOR-SAVING
SCREW HOISTING MACHINE,
FOR THE USE OF
Stores, Hotels, Warehouses, Factories, Sugar Refineries, Packing Houses, Mills, Docks, Mines, &c.
MANUFACTURED BY
CAMPBELL, WHITTIER & CO., ROXBURY, MASS.
Sole Agents for the New England States.

The above Engraving illustrates a very superior Hoisting Machine, designedfor Store and Warehouse Hoisting. It is very simple in its construction,compact, durable, and not liable to get out of order. An examination ofthe Engraving will convince any one who has any knowledge of Machinery,that the screw is the only safe principle on which to construct a HoistingMachine or Elevator.

Transcriber’s Notes:

The original text was printed with two columns per page.

Images have been moved from the middle of a paragraph to the closest paragraph break, so the placement of page numbers in this text does not exactly match the original in some cases.