Eifel hwcr Elemtor. —The great feature of the Paris Exhibition (1889) was the Eiffel tower, whose lofty height looks down on all the tall structures and monuments of the world. Of but little less interest is the means provided for the ascent of the tower, which, owing to the nature of its construction, presented unusual difficulties and rendered it impos sible to employ the ordinary " lifts." From the corners of a square whose sides theasure about 375 feet spring the four great legs of the tower, which converge in graceful vertical curves and meet at a point some 40o feet above the foundation. At this point is situated the "mid dle lauding" or second floor, whence the tower tapers to its apex. On each side of the square the four legs are connected by arches whose clear spans give architectural beauty to the design; to avoid obstructing these clearances all the means of ascent are placed in the legs and conform to their curves and inclination. The elevators, therefore, are of the charac ter of inclined railways of very steep angle and varying gradients. The original intention was to have an elevator which would rise from the base to the top of the tower, but the construction of the tower was such that a continuous passage or " well " could not be obtained. The difficulty was overcome by placing in each of two diagonally-opposite legs an elevator which ascends to the second floor, whence rise two elevators of the ordi nary type to the top. The remaining two diagonal legs are occupied by machines which rise on a straight incline to the first landing midway between the foundation and the middle The two elevators that presented the greatest difficulties of construction, on account of their ascent at varying inclinations, were of American design, built by Amer ican manufacturers, and successfully erected under their supervision.
Figure 3 (pi. tit) exhibits a diagonal section through one leg of the tower to the height of the middle landing, and gives a true profile of the track and track-structure on which the car (fig. 2) runs. The Figure also shows the hydraulic cylinder, the multiplying gear, the overhead work, the position of counterbalance and track, which lie directly under the main-track structure, and the car approaching the level of the first landing. The track starts at an angle of which inclination it keeps for some distance, and then, conforming to the contour of the leg, it passes by a vertical curve to an inclination of which is main tained to the end of the run at the middle landing, a distance of 42o feet, or to a vertical height of 395 feet from the foundation.
Figure 2 shows a side elevation of the car-frame, with a section of the car through the aisle and landing projections. The car is double-decked, the arrangement of both compartments being similar to that of an ordinary railway coach—that is, with seats on each side of a central aisle and at right angles to it. The peculiar feature of the car is the aisle floor, which pro jects in front of both compartments to meet the landing platforms, which are also double, one above the other, at each landing. This aisle floor is con structed like a Venetian shutter, the position of the slats being under the control of the operator by means of a lever. When the car is tt the bot tom of the tower it is considerably tipped back; the lever being put in the proper slot, each floor-slat is moved into a horizontal position, thus forming a series of steps or a stairway which the passenger descends to enter the car. At the first landing the lever is placed in the middle slot; the slats
are then horizontal, but they form an even floor, owing to the position of the car being between the two extremes of inclination, as shown in the Figure. When the car arrives at the top of its ascent it has a tipped forward position; the lever being again adjusted, the slats when horizon tal form a stairway, which the passenger ascends to enter the car. In this way the changes of angle in the car-frame are provided for to effect the landings. The seats, however, are stationary, but the backs and seats are so curved that the sitting passenger experiences no inconvenience from the change. of inclination. When he takes his seat in the car at the bottom of the tower he leans well back; upon reaching the top he finds his seat like a straight-backed chair and his body erect.
The motive power is a hydraulic machine whose cylinder (fig. 4) is 42 feet long and 38 inches inside diameter, constructed of four 9-foot sections of 2-inch cast-iron pipe jointed at their ends and bolted through their flanges. In addition to the four sections there is a short section at each end where connection is made with the circulating-pipe and water-chest. In this cylinder moves the piston, the machine being so geared that a t-foot movement of the piston effects a 12-foot movement of the car. Multiplication of speed is produced by the use of auxiliary pulleys, and the car is raised at the rate of goo feet per minute. To prevent acci dents through any disarrangement or breakage of the operating mechan ism, ingenious safety devices are introduced.
The elevators were built to carry fifty passengers per trip, but owing to the inadequacy of the pumping plant furnished by a French concern, the water-pressure was only sufficient to lift forty passengers per trip. Both elevators were intended to run from the ground to the second land ing-, but it was found that the people would be better distributed to the various stories of the tower if one of the elevators should run during cer tain hours of the day only between the first and second landings. The tower was open to the public at 9 A. Al. and remained open until io P. M., or thirteen hours. In this time No. f elevator carried 832o people up and down, and No. 2 elevator carried f 1,44o, making a total of 19,760 carried each day during the exhibition. The No. i elevator made its run of 42o feet in one and a half minutes each way, and with the two minutes required at each terminal for loading and unloading, made the round trip in seven minutes, an average of eight trips per hour. No. 2 elevator made its run of zoo feet in forty-five seconds, and with the time required for loading and unloading its passengers, made a round trip in five and one-half min utes, or eleven trips per hour, each elevator carrying its complement of forty persons. This rate of speed was that fixed upon by the commission, but No. i elevator under a test made the run from the ground to the sec ond story in forty-five seconds.