116 HYDROSTATICS. 



down with a power equal to one ton, then the rod 

 of the great cylinder will be forced up with a 

 power equal to 576 tons. To increase the power 

 of this press to any degree, it is only necessary to 

 make the great cylinder exceed the smaller in any 

 required proportion : and this machine has the 

 advantage of great simplicity and little loss from 

 friction. 



Mr. Bramah has also employed the same prin- 

 ciple to the construction of a jack for raising stones; 

 and also of a crane, by adding a rack to the rod of 

 the great piston, which drives a wheel that has a 

 chain passing over a jib. 



From the principles above described of the pres- 

 sure of fluids, water is conveyed by means of pipes 

 to any distance, and to any height not exceeding 

 the reservoir: thus in Plate 25. fig. 5. A represents 

 a reservoir of water, either supplied by natural 

 streams, or kept full by forcing engines: the water 

 may be conveyed by the pipe, BCD, across the 

 valley to the house at D, and will rise to the top of 

 the building, provided that it is not higher than the 

 reservoir ; whereas, if the pipe be continued to the 

 house, E, it will not rise to the top, because it 

 stands higher than the level of the reservoir. 



When it is required to carry the water higher up, 

 the reservoir must be also raised higher: sometimes 

 water is forced up to the top of a town, to supply 

 houses on a high ground. 



On this principle may be explained the rising of 

 water in springs. The vapours raised by evapo- 

 ration from the sea form clouds, which afterwards 

 descend in rain on the hills and high ground: the 

 water so formed, percolates through the soil, and 

 sinks into the looser and more porous strata: it 



