HYDRAULIC ELEVATORS AND MOTORS. 141 
increased fire pressure at a moment's notice, into either or both pipe systems. 
Thus at some points the pressure is extremely high during the progress of fires, 
causing difficulties that do not exist where the gravity system is used exclusively. 
Elevators have become an established institution and in cities of any com- 
mercial importance, are regarded as a necessity; hotels, jobbing houses, factories, 
and office-buildings being considered as far behind the times when not thus pro- 
vided, as a city without a water-supply or a community without a " boom." The 
use of elevators has made it practicable and profitable to erect buildings twice as 
high as were formerly thought of. Perhaps some of the most notable examples 
of this are in New York City, where such structures as the Mills Block, the 
buildings of the "Tribune,'' "Evening Post" and Western Union Telegraph 
Company, tower high above the surrounding blocks, monuments of architecture 
that, without this modern invention, would reflect little credit upon their de- 
signers. If then, they have become such a firmly established institution, their 
bearing upon the water-supply of cities is a subject to be carefully considered. 
As before intimated, there are many questions involved in the use of hydraulic 
elevators, that particularly concern towns supplied by direct pumping, and per- 
haps other places where the supply by gravity is somewhat limited. In a few 
larger cities supplied by ample reservoirs and mains, some of the difficulties sug- 
gested are not serious. Very little powefr is necessary to perform the actual work 
of lifting, with either steam or hydraulic elevators, but on account of the peculiar 
application of the power and the great amount of friction to be overcome, a very 
considerable power has to be provided. It has been estimated, by good author- 
ities, that not more than one-quarter of the power expended in most cases, is. 
really utilized. 
With all hydraulic elevators of which I have cognizance, as much water is 
required to raise the empty cars as though they were loaded to maximum capacity. 
Still, to be available for passenger purposes, elevators must have capacity of 
upward of 2500 pounds, particularly in hotels where the cars are often arranged 
with separate compartments underneath for baggage. In general use it is excep- 
tional that passenger elevators are fully loaded, on the contrary less than half a 
load is ordinarily carried, and for this reason it would appear that no actual bene- 
fit is derived from at least one-half of the water consumed. In this connection it 
has occurred to me that passenger elevators could be built at no great additional 
cost, with two cylinders, small and large, the two piston rods of which could be 
connected so as to both operate the same cable, either or both furnishing power. 
The smaller cylinder to be used for light loads, the larger for heavy work, and 
the two together for full capacity. This independent valve arrangement to be 
controlled by a separate cable running through the car. Whether this plan is 
practicable or not must be left to elevator manufacturers, but it seems to me that 
with the Hale Otis Elevator, for instance, (which is conceded to be one of the 
best) it could easily be accomplished. Certainly some such arrangement would 
effect a great saving of water, and perhaps bring water bills to a point that this 
class of consumers could afford to pay. 
