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

 TABLE I.

67. 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. 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;

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