NOTES. 161 



7. Volta, Alessandro, an Italian physicist, was born at Como, on 

 February 18, 1745. His reputation rests upon his invention, in 1799, 

 of the instrument known as the Voltaic pile. 



8. envergure : scope, breadth. 



9. Ampere, Andre"-Marie, the founder of the science of electro- 

 dynamics, was born at Lyons, in January, 1775. 



10. Ohm, Georg Simon, was born at Erlangen (Bavaria), in 1787, 

 and became in 1852 professor of experimental physics in the university 

 of Munich. 



n. Sir William Thomson, now Lord Kelvin, was born at Belfast 

 in 1824, and is a very distinguished physicist. His quadrant elec- 

 trometer, new absolute electrometer, and his reflecting galvanometer, 

 are well known. 



12. Faraday, chemist, electrician, and philosopher, was born at 

 Newington (England) on the 22d of September, 1791. To him is due 

 the first experimental machine for the mechanical production of electric 

 currents. 



13. Pacinotti, Antonio: bom in 1860; devised a machine to pro- 

 duce an electric current continuous in character, and constant hi direc- 

 tion and intensity. He is the inventor of a ring inductor, a remarkable 

 improvement in magneto- and dynamo-electric machines. 



14. Gramme, The*ophile : the inventor of a new form of magneto* 

 electric machine, known as the alternating-current machine. 



15. 10%, read: dix pour cent. 



16. Clerk Maxwell, James, was born in 1831 at Edinburgh ; died 

 November 26, 1879. He became professor of experimental physics 

 in Cambridge (England). His was one of the master-minds among the 

 electricians of the new era. 



17. Hertz, Henry: born on the 22d of February, 1857, at Hamburg 

 (Germany), and is now a professor in the university of Bonn. 



XXXVIII. LES NOUVEAUX HYGROMETRES. 



1. Tables de Re'gnault : showing the specific heat of all the elements 

 obtainable and of many compounds. Henri Victor Regnault (1811- 

 1878) was born at Aix-la-Chapelle, and became professor of physics in 

 the College de France. 



2. comportent: imply. 



3. plus conducteurs : better conductors. 



4- tubes en U de rechange : reserve U-tubes. 

 5. ascension alrostatique : balloon ascension. 



