MR. RENNIE ON THE FRICTION AND RESISTANCE OF FLUIDS. 435 
Table VII. 
Experiments on the Quantity of Water discharged by Cylindrical Glass 
Orifices and Tubes, from one inch in length to one foot, and of different 
diameters, from a vessel kept constantly full, and at different heights. 
Constant height 
of the surface of 
water above the 
centre of orifice. 
Time in seconds in discharging 
one cubic foot. 
Remarks. 
1 inch. 
Jin. 
£in. 
fin. 
feet. 
4 
11.5 
24.5 
55 
145 
In comparing these experiments with 
the time and quantity discharged by 
3 
15.0 
28.5 
63 
157 
plate orifices, there is a diminution of 
2 
17.5 
35.0 
77 
205 
time, and an increased discharge of 
1 
25.0 
53.0 
110 
297 
from J- to 
From Glass Tubes one foot long. 
1 inch. 
fin. 
§ in. 
{in. 
4 
14.0 
30 
63 
200 
Shows an increase of time and a dimi- 
3 
17.0 
33 
73 
227 
nution of discharge in the ratio of 
2 
21.5 
40 
88 
283 
from to {. 
1 
30.0 
58 
130 
410 
Conclusions. 
] . That the quantities discharged in equal times by orifices and additional tubes, are as the areas of 
the orifices. 
2. That the quantities discharged in equal times by the same additional tubes and orifices under 
different heads, are nearly as the square roots of the corresponding heights. 
3. That the quantities discharged in equal times by the different additional tubes and orifices under 
different heights, are to one another in the compound ratio of the areas of the apertures, and of the 
square roots of the heights. 
From the foregoing experiments the mean coefficient for altitudes of 4 feet with the circular orifices, 
is 0.621 
but with altitudes of 1 foot the coefficient is 0.645 
with triangular orifices at 4 feet altitude 0.593 
with triangular orifices at 1 foot altitude 0.596 
with rectangular orifices at 4 feet altitude 0.593 
with rectangular orifices at 1 foot altitude 0.616 
Hence, allowing for the inaccuracies incident to experiments of this nature, we may safely adopt 
Messrs. Proxy and Bossut’s coefficients for altitudes of 4 feet 0.621 
1 foot 0.619 
In the case of additional tubes of glass the coefficient is much higher than Bossut’s, which was for 
4 feet 0.8C6, and 1 foot 0.817. 
Note . — Vide Venturi and Eytelwein’s experiments. 
