8 
Mr. Vince's Experiments on the Resistance 
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through a simple orifice, the velocity would have been that 
which is acquired in falling through half the depth ; the pipe 
of the stop-cock therefore increased the velocity of the fluid in 
the ratio of 1 : \Z¥, and gave it the greatest velocity possible ; 
the length of the pipe was 3 in. and the area of the section 
0,045 in. ; also, the base of the vessel was a square, the side of 
which was 12 inches. 
The area of the section of the pipe may be found very accu- 
rately, in the following manner. The vessel being kept con- 
stantly full, receive the quantity of fluid run out in any time t", 
and then weigh it, by which we shall be able to get the quan- 
tity in cubic inches. Now if v = the velocity of the fluid when 
it issues from the pipe, a = the area of the section of the pipe, 
l = the length of the cylinder of water run out, whose base 
— a , and m = the quantity of fluid discharged in t" ; then 
v : 1 ":t", hence, l = vt ; but al — m ; therefore a v t = m ; 
hence, a = In the present instance, t— 20, m= 170,63 
cubic inches, v = 189,6 ; hence, a = 0,045. 
Let AB C D (fig. 1. Tab. I.) be a solid piece of wood, upon 
which are fixed two upright pieces, r s, tu ; between these, a 
flat lever e a c is suspended, in a perpendicular position, on the 
axis x y, and nicely balanced ; and let a be a point directly 
against the middle of the axis, in a line perpendicular to the 
plane of the lever. This apparatus is placed against the stop- 
cock, at the distance of about 1 inch, and, when the water is let 
go, let us suppose the centre of the stream to strike the lever 
perpendicularly at e ; take a c == a e, and, on tfie opposite side to 
that at which the stream acts, fasten a fine silk string at c, and 
bring it over a pulley p, and adjust it in a direction perpendi- 
cular to the plane of the lever, and, at the end which hangs 
