Physics 529 



ELECTRICITY AND MAGNETISM 



THE first paper under this head which the Smithsonian Insti- 

 tution brought out was one on terrestrial magnetism, the 

 first of a long and valuable series of publications on that sub- 

 ject. It appeared in 1852, in the " Smithsonian Contributions 

 to Knowledge." 1 The paper consisted of a series of obser- 

 vations made in the years i845~'46-'47 to determine the "dip 

 inclination and intensity " of magnetic force in various parts 

 of the United States. Its author was Doctor John Locke, 

 of Cincinnati, Ohio, a well-known pioneer in Western sci- 

 ence. Doctor Locke was the inventor of the chronograph, 

 which was first used in astronomical observations at Cin- 

 cinnati. The method of observing transits by its use rap- 

 idly came into favor, was adopted by the United States 

 Coast Survey, and came to be universally known as the 

 " American Method." Doctor Locke's observations on ter- 

 restrial magnetism were highly esteemed by Sabine, who 

 made use of them in his contributions to that subject. 



The same volume of "Contributions" contained another 

 paper of great interest and theoretical importance on " Elec- 

 trical Rheometry," by Father Secchi, then recently made pro- 

 fessor of astronomy and director of the Observatory in Rome, 

 after having served for a few years as professor of physics in 

 the Georgetown College, District of Columbia. His astro- 

 physical work in later years brought him great fame. The 

 memoir is a mathematical solution, with experimental verifica- 

 tion of the problem, " to find the action of a closed current 

 on a magnetic needle, whatever be its position relative to 

 that of the current," and Secchi's treatment of the problem 

 is of much interest, even to electricians of to-day. 



1 Volume III, page 5. 



