OF HYDRAULICS. 



123 



poise ; which weight will be found to answer exactly to 



the additional weight of the phial when it is again weigh- ^x-v-x^ 



ed in air, with the water in it 



The velocity with which water spouts out at a hole The velo- 

 in the side or bottom of a vessel, is as the square root* 

 of the depth or distance of the hole below the surface 

 the water. For, in order to make double the quantity 

 of a fluid run through one hole as through another of 

 the same size, it will require four times the pressure of 

 the other, and therefore must be four times the depth of 

 the other below the surface of the water ; and for the 

 same reason, three times the quantity running in an 

 equal time through the same sort of hole, must run with 

 thjee times the velocity, which will require nine times 

 the pressure; and consequently must be nine times as 

 deep below the surface of the fluid : and so on. To 

 prove this by an experiment, let two pipes, as C and g, 

 of equal sized bores, 

 be fixed into the side 

 of the vessel AB ; the 

 pipe g being four 

 times as deep below 

 the surface of the wa- 

 ter at 6 in the vessel 

 as the pipe C is : and 

 whilst these pipes run, 

 let water be constant- 

 ly poured into the 

 vessel, to keep the 



surface still at the same height. Then, if a cup that 

 holds a pint be so placed as to receive the water that 

 spouts from the pipe C, and at the same moment a cup 

 that holds a quart be so placed as to receive the water 



Note 45. The square root of any number is that which being multi- 

 plied by itself produces the said number. Thus, 2 is the square root 

 of 4, and 3 is the square root of 9 : for 2 multiplied by 2 produces 

 4, and 3 multiplied by 3 produces 9, &c. AWe by the Author. 



