INGENUITY AND LUXURY 



buildings, such as private dwellings, where it is not 

 practical to keep a steam-boiler going at all times, 

 soon made inventors look about them for other kinds 

 of power. The most obvious one, and incidentally 

 the oldest, was hydraulic pressure; and early in the 

 seventies "hydraulic water balance elevators" were 

 introduced and for a time rivalled steam elevators 

 in popularity. 



The principle upon which these elevators worked 

 was that of the balance, in which the heavier of two 

 suspended weights caused the lighter one to rise. As 

 applied to these elevators, an iron tank of water at 

 one end of the hoisting cable acted as a weight for 

 raising the cage at the other end of the cable. By 

 means of valves water was admitted into the tank until 

 its weight was greater than that of the loaded cage, the 

 amount of water required depending upon the weight 

 to be lifted. For lowering the cage the water was run 

 out of the tank, allowing the cage to descend by its 

 own weight, the speed being controlled by friction 

 brakes. 



Despite the popularity of such elevators they were 

 expensive to install and maintain, and rather compli- 

 cated, and a few years after their introduction were 

 displaced by the horizontal hydraulic type of elevator 

 invented by the English engineer, William Armstrong. 

 This type of hydraulic elevator, and its modified ver- 

 tical form, are used to-day in greater numbers than 

 any other form, although electric elevators are rapidly 

 overhauling them in popularity. 



Unlike the "water balance elevator" the horizontal 



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