HYDRAULICS. 



tenth to one-sixth, according to the con- 

 struction of the pump for friction. The 

 load upon an excentric or any other 

 pump may be found by the same rule if 

 the effective horizontal area of the pis- 

 ton, or its substitute, be found, and this 

 be in like manner multiplied into the 

 height of the lift. It therefore becomes 

 important to know the weight and 

 quantity of water which a certain 

 length of pipe of any given diameter 

 will contain, and a tolerably close ap- 

 proximation to this may be obtained by 

 squaring the diameter of any pipe in 

 inches, and cutting off the last figure 

 of the product by a decimal point, which 

 will nearly give the contents in ale gal- 

 lons of one yard in length of such pipe. 

 Thus, for example, if a pipe is six 

 inches in diameter, 6 times 6 make 36, 

 and introducing the decimal point 

 would reduce this number to 3.6, so 

 that one yard of such pipe would con- 

 tain three gallons and six-tenths. If a 

 three-inch pipe had been taken, then 

 3x3=9; consequently, there remains 

 but one figure to cut off. The gallons' 

 place must therefore be supplied by a 

 cipher, thus 0.9, and the yard of such 

 pipe would contain but nine-tenths of a 

 gallon. 



For greater certainty, however, the 

 following table and rules are intro- 

 duced. They are extracted from " Brun- 

 ton's Compendium of Mechanics ;" a 

 recent little work, published at Glas- 

 gow, and which is so replete with use- 

 ful information, that no working me- 

 chanic should be without it. 



TABLE 



Of the contents of a pipe one inch dia- 

 meter for any required height. 



Although the above Table only gives 

 the contents of a pipe one inch in dia- 

 meter, it will serve as a standard for 

 pipes of any other size, by observing 

 the following 



RULE. Multiply the numbers found 

 in the table against any height, by the 

 square of the diameter of the pipe, and 

 the product will be the number of cubic 

 inches, avoirdupois ounces, and wine 

 gallons of water, that the given pipe 

 will contain. 



EXAMPLE. How many wine gal- 

 lons of water are contained in a pipe 

 six inches diameter, and sixty feet 

 long? 



2.4480x36 = 88.1280 wine gallons. 



The wine gallon contains 231 cubic 

 inches, and the new imperial gallon 

 277.274 cubic inches ; therefore, to re- 

 duce the wine to the imperial gallon, 

 divide by 1.20032; and for a like re- 

 duction of the ale gallon, which contains 

 282 cubic inches, divide by 0.98324. 



CHAPTER III. 



Of the Force and Power to be derived 

 from Fluids in Motion. 



HYDRAULICS contemplates not only the 

 construction and action of machines 

 for raising water above its level, such 

 as those that have been last described ; 

 but likewise the means by which motion 

 and power may be obtained from the 

 motion and other properties of fluids. 

 Accordingly a brief examination of the 

 various mill or water-wheels and other 

 contrivances, by which motion is given 

 to machinery, will form the conclusion 

 of the present essay. 



Motion is generally obtained from 

 water, either by exposing obstacles to 

 the action of its current, as in water- 

 wheels, or by arresting its progress 

 in movable buckets or receptacles 

 which retain it during a part of the 

 progress of its descent. Thus, if we 

 suppose the action of the Persian 

 wheel shown skfi-g. 4, to be the reverse 

 of what it has been described to be, 

 viz. that instead of the buckets n o p 

 receiving their water from the stream 

 r r, and delivering it into the elevated 

 cistern s, we imagine the cistern s to 

 be supplied by the stream, and that the 

 several buckets o o o n shall become 

 filled with water instead of emptied by 

 passing the cistern s, the side o o o of 

 the wheel will become heavier by the 

 weight of all the water that the buckets 

 contain, than the opposite side q q, in 

 which the buckets are supposed to re- 



