Page:Lowell Hydraulic Experiments, 4th edition.djvu/48

 was covered with a solid coating of ice, with scarcely an opening in the whole distance. When the river is thus frozen, the water flows along under the ice, entirely free from floating particles of ice, even in the most severe weather.

As the author had frequently felt the want of a table of the absolute weights of a cubic foot of water at different temperatures, he, several years since, computed the following table.

In the Encyclopedia Britannica, seventh edition, vol. 21, page 846, is given the following extract from the British act of Parliament, establishing the standards for weights and measures.

"Provided always, and be it enacted, that in all cases of dispute respecting the correctness of any measure of capacity, arising in a place where recourse cannot conveniently be had to any of the aforesaid verified copies or models of the standard measures of capacity, it shall and may be lawful, to and for, any justice of the peace, or magistrate, having jurisdiction in such place, to ascertain the content of such measure of capacity by direct reference to the weight of pure or rain water which such measure is capable of containing; ten pounds avoirdupois weight of such water, at the temperature of 62° by Fahrenheit's thermometer, being the standard gallon ascertained by this act, the same being in bulk equal to 277.276, 1822 (1823, 277.274) cubic inches, and so in proportion," etc. 277.274 cubic inches was taken, as it appeared to be the latest determination.

In the first volume of the Traite de Chimie, by J. J. Berzelius, second French edition, Paris, 1846, there is given a table of the specific gravities of pure water, at different temperatures of the centigrade scale, deduced from Haellstroem's experiments.

From these two authorities were derived the data for the following table.