it by its action on a feather.
Small hollow glass spheres called bubbles are also used in testing spirits, the rate at which they ascend therein being a gage of the gravity of the liquid.
The hydrometer was in all probability invented by Archimedes, who was killed in the storming of Syracuse, 212 B. C. His discovery of the mode of ascertaining specific gravity by displacement of liquid is referred to by many writers of Europe, Asia, and Libya.
Seneca, Pliny, and Galen, who flourished dcribed by Abu-Jafar Al-Khazini, an eminent Saracenic writer of the twelfth century, and is credited to Pappus, a Greek philosopher, who was contemporary with Theodosius the Great, A. D. 379 – 395.
Al-Khazini refers to the original discovery of Archimedes, upon which the instrument is based, and takes a very pious view of the line of discovery.
See the Book of the balance of wisdom, in Vol.
VI. of the Journal of the American Oriental Society, New Haven, 1860.
See supra, pp. 141, 142.