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SCIENCE. 23 



STEAM AND HYDRAULIC SAFETY ELE- 

 VATORS. 



In large cities, where every inch of land is precious, 

 the modern power elevator has virtually effected for 

 building, what the kcomotive engine has effected for 

 travel and transportat on — namely, a revolution. Hotels 

 office buildings, apartment houses, and first-class stores, 

 are now almost invaiiably carried to a height of eight cr 

 ten stories, and equipped With elevators ; while a ten- 

 dency is fast growing and will soon become controlling, 

 to increase the value of third and fourth rate property in 

 the same way, and even to eliminate the toil of stair-climb- 

 ing from ordinary housekeeping. This great change in 

 the condi ions of living, together with the progressive 

 fatality already developed, as elevators without adequate 

 safeguards begin to wear and weaken, will soon be call- 

 ing in terrible tones for legislative interference. Fortu- 

 nately, there are standard safety appliances that have 

 stood the test of every possible description of breakage 

 and accident to which elevators are liable, during a quar- 

 ter of a century past, without a single failure. The sole 

 reason that we hear from time to time of cruel destruction 

 to human life from the falling of elevators in our hotels and 

 apartment houses, etc., is that there are proprietors too 

 parsimonious, or too ignorant, to provide their buildings 

 with the perfect and proved safeguards that are every- 

 where before their eyes in the standard pattern of eleva- 

 tors used in nearly all of the most valuable buildings. 

 They ought to be compelled to do so, whoever may 

 profit or lose by the requirement. Meanwhile, let us see 

 what individuals can do to protect themselves against 

 these people by avoidance. 



The improved modern safety device, introduced 

 by Otis Brothers $c Co., in their best eleva- 

 tors, for -some years past, is quite outside and in- 

 dependent of the other mechanism, and acts instanta- 

 neously by virtue of any acceleration of the standard 

 rate of motion in the car, from whatever cause. Both 

 arrangement and action are simplicity itself. There 

 is an independent sheave at the top and another at the 

 bottom of the hoist well or shaft, and an endless wire 

 rope running around the two ; the lower sheave being 

 suspended, to keep the rope taut. The rope is connected 

 at a proper point with the safety catches on the 

 car, in such a manner as to run the rope as the car 

 moves, and thus to run a pair of governor balls geared 

 to the top sheave. If the car should commence de- 

 scending faster than the rate for which the governor is 

 set — whether by accident, by overloading, or by indiscre- 

 tion of the operator — the extension of the governor balls 

 by the accelerated motion (greatly multiplied on the gov- 

 ernor) instantly operates a clutch on the rope which 

 pulls out the ca ches into the safety ratchets, and 

 stops and locks the car in its place. It is like an au- 

 tomatic iron hand, always ready to clutch and pull the 

 rope that arrests the car, the moment it discbeys the 

 set restriction on its rate of descent. It is literally im- 

 possible by any means to move the car downward 

 faster than the rate prescribed. 



HYDRAULIC ELEVATORS. 



For the purpose most interesting to the general reader 

 — that of passenger elevators — the very recently perfected 

 application of hyuraulic power has controlling advantages, 

 and it is probable that most pasasnger elevators will 

 hereafter be constructed on this principle. The best 

 hydraulic elevators are preferred to steam for this. pur- 

 pose on account of the perfect smoothness of their mo- 

 tion, their remarkable simplicity of construction and op- 

 eration, easy management, and reduced opportunities for 

 breakage, derangement or accident. To these advantages 

 they add that of reduced expense for motive power to 

 the extent of the head of water available on the premises. 

 It is not to be understood, however, that all hydraulic 



elevators share in this preference. Most kinds heretofore, 

 in fact have cost more in wear and tear of ropes and 

 other parts, and in motive power to overcome extra fric- 

 tion, weight, &c, than any kind of steam elevators. 



We shall make it our object to put the reader in pos- 

 session of the leading criteria and piinciples necessary 

 for a correct judgment among different hydraulic eleva- 

 tors in the remainder of this article. 



Generally the less desirable kinds of hydraulic eleva- 

 tors are made with a short cylinder of large diameter, 

 into which the pressure of a heavy column of water is in- 

 troduced at one end, urging a solid piston like that of a 

 steam engine from that end to the other. The piston rod 

 pushes forward a crosshead bearing on each side of it a 

 block of multiplying sheaves or pulleys around which the 

 wire rope (from the sheave at the top of the hoist) passes, and 

 returns many times to and from a similar pair of multiplying 

 blocks in a fixed position at the rear of the cylinder. As 

 these blocks ot sheaves are thus forced farther apart by 

 the motion of the piston, lengthening each of the twenty 

 turns (more or less) of the wire rope between theTnT a 

 length of rcpe many times the length of the piston stroke 

 is obviously thus tak>:n up, and the car is hoisted an equi- 

 valent distance. It is the same in effect as winding up 

 the rope on a drum : but it is not so favorable in mode ; the 

 friction and strain being exces ively increased. More- 

 over, the course of the wire rope from sheave to sheave 

 in the blocks, must necessarily cross the plane of revolu- 

 tion of each sheave, both in taking and leaving it, so that 

 the edge of every groove continually and severely rasps 

 the rope as it runs in'o it and out of it under a tension 

 of tons force. In point of fact, these ropes have to be 

 frequently renewed, not only at considerable expense, but 

 at much inconvenience from interruption. But a worse 

 result is their great liability to snap suddenly at some 

 point, and not only throw the enotmcus tension out of 

 balance and the labyrinth of rope and blocks into violent 

 snarl and wreck, to the des' ruction of everything animate 

 or inanimate within reach ; but at the same lime, to cause 

 the car to fall the whole distance to which it may have 

 been raised. Another objection, of course, is the con- 

 stant extra cost of power lor the ex reme friction pecuhar 

 to this mode of multiplying motion. The substitution of 

 a rack of cog teeth on the piston rod, gearing into a pin- 

 ion wheel, and that into a geared winding drum, does not 

 mend the matter in point of safety or economy, since it is 

 not practicable to use a belt from so slow a motor. Some 

 of tins class of machines are made doubly objectionable 

 by placing the cylinder horizontally. The lift weight of a 

 vertical piston can be counterbalanced ; but this arrange- 

 ment makes a nett increase of friction by the dead weight 

 of the heavy piston to be dragged on the bottom side of the 

 cylinder. Two other disadvantages are not to be avoided 

 or counteracted : the constant wear of the cylinder and 

 piston out of round by dragging the lat er on its under 

 side, and the accumulation unde r it of sediment from the 

 water, to assist in the work of abtasion. 



We conclude with a description of the more modern 

 and matured form ot hydraulic elevator, adopted for the 

 Government buildings, on the unanimous recommendation 

 of a board of experts appointed by the Secretary of the 

 Treasury, and composed of Messrs. Frederick Graff, C. 

 E., of Philadelphia ; Master Machinist Geo. A. Wilson 

 of the Washington Navy Yard ; and Clvef Examiner J. 

 B. Durnall of the Patent Office. Their decision was 

 made after exhaustive investigation in the principal cities 

 and manufactories ; and from the fact that out ot nine 

 competing methods only one was considered worthy of 

 mention in their report, and that in terms of almost en- 

 thusiastic admiration, the reader may judge that the rela- 

 tive objections and advantages are fairly stated in this 

 brief review. Six of these elevators have been running 

 for three years, uninterupted for repair, in the "Boreel " 

 and " Morse " buildings, and similar ones are going up in 

 other famous piles, such as the " Vanderbilt," " Mills, 



