434 MR. RENNIE ON THE FRICTION AND RESISTANCE OF FLUIDS. 
Table VI. 
Experiments on the Quantities of Water discharged from Rectangular and Tri- 
angular Orifices in brass plates one sixtieth of an inch thick, and of equal 
areas, from a vessel kept constantly full and at different heights. 
Equilateral Triangle whose area is one inch, and angle uppermost. 
Constant height of 
the surface of the 
water above the 
centre of the orifice. 
Time in discharg- 
ing one cubic foot. 
Theoretical time in 
discharging one 
cubic foot, 
Q 
2 A Vga' 
Ratio of real to 
theoretical dis- 
charge. 
Form of orifice. 
feet. 
4 
3 
2 
1 
seconds. 
15 
18 
22 
30 
seconds. 
8.9 
10.3 
12.7 
17-9 
1 : .593 
1 : .572 
1 : .577 
1 : .596 
Vena contracta about half an inch 
beyond the orifice ; hut the jet 
with the angles reversed, and 
taking the sides of the trian- 
gle, the jet afterwards ex- n- 7 
' panded and lost its form. \ / 
Equilateral Triangle as before, with the angle downwards. 
4 
15 
8.9 
1 : .593 
Vena contracta the same as be- 
fore, but the jet having its angle 
upwards, being the reverse \ 
of the former experiments. / \ 
Rectangular Orifice of one square inch. 
4 
3 
2 
1 
15 
17 
20 
29 
8.9 
10.3 
12.7 
17-9 
1 : .593 
1 : .606 
1 : .635 
1 : .617 
Vena contracta about three quar- 
ters of an inch beyond the orifice, 
when each angle of the jet took 
the place of a side thus, '"TV" 
and dissipated in spray. •>? 
Rectangular Orifice 2 inches long, A an inch wide, having the long side parallel to the surface 
of the water. 
4 
3 
2 
1 
15 
17 
20 
29 
8.9 
10.3 
12.7 
17-9 
1 : .593 
1 : .606 
1 : .635 
1 : .617 
Vena contracta as before. Each 
angle of the jet took the place 
of a side. 
Rectangular Jet 1| inch long, wide, placed as before. 
4 
3 
2 
1 
15 
17 
19 
27 
8.9 
10.3 
12.7 
17.9 
1 : .593 
1 : .606 
1 : .668 
1 : .663 
Vena contracta as before. 
Remarks. 
That with equal areas, the expenditure by different orifices, whether circular, rectangular, or tri- 
angular, is nearly the same, the increase being in favour of rectangular orifices. 
