BIOGRAPHICAL INDEX 



Etienne, France, Oct. 31, 1802; died at Paris, 

 July, 1867. French engineer who improved the 

 construction of turbine water-wheels. 



Franklin, Benjamin, ii, 286. Born at Boston, 

 1706; died at Philadelphia, 1790. American 

 scientist and statesman. Apprenticed to a printer 

 he soon went to Philadelphia and began a life 

 of great public activity, rendering great service 

 to his country in many ways. He held political 

 offices, spent much time in Europe on behalf of 

 the colonies, and later as an emissary of the 

 new American nation to obtain help from 

 France. In 1731 he started the Philidelphia Li- 

 brary. In 1744, founded the American Philo- 

 sophic Society. Invented the Franklin stove, 

 made many civic improvements, and made valu- 

 able investigations in electricity, demonstrating 

 the electrical nature of lightning (1752). 



Frauenhofer, Joseph von, iii, 60.. Born at 

 Straubing, 1787; died at Munich, 1826. German 

 physicist. Began life as a working optician and 

 became head of a firm of opticians. Invented 

 means of obtaining large piece of optical glass 

 free from imperfections for lenses and prisms. 

 Many inventions to perfect making of lenses, 

 prisms, etc. Discovered the dark lines in the 

 spectrum called by his name. Measured the 

 wave lengths of sodium light by means of dif- 

 fraction grating. 



Fresnel, Augustin Jean, iii, 226. Born at Brog- 

 lie, 1788; died near Paris, 1827. French physi- 

 cist. Educated Caen and Paris. Became Gov- 

 ernment engineer. Independently of Young he 

 demonstrated the falsity of the Newtonian the- 

 ory of light, and advocated the undulatory the- 



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