Page:Lowell Hydraulic Experiments, 4th edition.djvu/49

Table I.

Weight of a cubic foot of pure water at different temperatures.

Temperature, in degrees of Fahrenheit's thermometer.	Weight in air, of a cubic foot of pure water. Pounds avoirdupois.	Temperature, in degrees of Fahrenheit's thermometer.	Weight in air, of a cubic foot of pure water. Pounds avoirdupois.	Temperature, in degrees of Fahrenheit's thermometer.	Weight in air, of a cubic foot of pure water. Pounds avoirdupois.
32	62.375	50	62.368	69	62.278
33	62.377	51	62.365	70	62.272
34	62.378	52	62.363	71	62.264
35	62.379	53	62.359	72	62.257
36	62.38	54	62.356	73	62.249
37	62.381	55	62.352	74	62.242
38	62.381	56	62.349	75	62.234
39(max.)	62.382	57	62.345	76	62.225
39.38	62.382	58	62.34	77	62.217
40	62.382	59	62.336	78	62.208
41	62.381	60	62.331	79	62.199
42	62.381	61	62.326	80	62.19
43	62.38	62	62.321	81	62.181
44	62.379	63	62.316	82	62.172
45	62.378	64	62.31	83	62.162
46	62.376	65	62.304	84	62.152
47	62.375	66	62.298	85	62.142
48	62.373	67	62.292	86	62.132
49	62.371	68	62.285

67. Column 17. Ratio of the useful effect to the power expended. This column is obtained by dividing the numbers in column 10 by those in column 16.

68. Column 18. Velocity due to the fall acting upon the wheel. The numbers in this column have been calculated by the formula

$$V={\sqrt {2gh}}.$$

V = the velocity in feet per second.

g = the velocity acquired by a body at the end of the first second of its fall in a vacuum.

h = the fall acting upon the wheel; this is given in column 13.

The value of g has been calculated by the formula given in the second edition of the Traité D'Hydraulique, by D'Aubuisson, page 5, viz.: —

$$g=9^{m}.8051(1-0.00284\ \mathrm {cos.} \ 2l)(1-{{2e} \over {r}});$$

l being the latitude of the place; e, its elevation above the level of the sea; and r, the radius of the terrestrial spheroid, at the level of the sea, and at the place;

$$\{r=6366407^{m}(1+0.00164\ \mathrm {cos.} \ 2l.)\}.$$