280 



OF THE APPLICATION 



[SECT. ix. 



at first in the proportion due to an uniform force ; otherwise the motion will be 

 irregular, and the loss of power considerable. The weight of a stamper is usually 

 made about 190 Ibs., and the height it is raised about 2 feet ; and not less than 

 two-thirds of the stampers should be rising at any instant of time. 



WATER WORKS. 



581. The same formulae apply to water works as to other modes of 

 raising water, when it is raised perpendicularly; but as this is seldom the case, 

 instead of adding 1'5 feet for each lift, as in art. 572, 



add 



140 a 



feet to the vertical height ; 



where v is the velocity in feet per second, L the length of the main in feet, 

 and a its diameter in inches : add also one-tenth of the height for the friction 

 of the piston, and proceed in other respects as in the article referred to. 



582. The supply of a town should be ten cubic feet per day for each house, 

 and for the averaged sized houses this is not more than comfort and cleanliness 

 requires ; or two cubic feet per day for each individual, besides what is required 

 for watering streets, for breweries, engines, and various purposes; and for these 

 purposes two cubic feet more ought to be delivered in summer, making a total of 

 four cubic feet per day for each person, for the greatest quantity : in small and open 

 towns a less quantity of water is required ; but even in these, two cubic feet and a 

 half ought to be calculated upon. 1 In raising water by forcing, the air vessel 

 should always be in the direction of the motion of the fluid, and not to one side 

 of it ; want of attention to this, causes those concussions to take place which tear 

 the joints asunder, break the cranks, and spoil the machinery. Double engines 

 with fly wheels are the most economical when fuel is dear, (art. 419.) and single 

 engines where it is cheap, (art. 411 and 400.) See Plates xn. and xin. 



1 The following table is compiled chiefly from Leslie's Nat. Phil., with some additions, and 

 a more reasonable estimate of the quantity supplied to ancient Rome. 



