PHYSICS OF THE GLOBE. 107 



to west on the northern side, and from west to east on the 

 southern side, the north side would be attracted, and the 

 south side repelled by the earth currents, both influences 

 combining to deflect the beam of the balance. On revers- 

 ing the current the deflection was in the opposite direction 

 (Nature, vol. xvii., p. 281). 



The annual report of the United States Coast Survey for 

 1874-75 contains in its numerous appendices some highly 

 important contributions to terrestrial physics. Among these 

 we especially note the voluminous report of C. A. Schott 

 on the Secular Change of Magnetic Declination in the 

 United States and North America. This change, although 

 well represented by the so-called circular functions, yet need 

 not be of a periodic nature. The circular function merely 

 represents the phenomena observed during the past few 

 centuries, and nothing should be inferred as to the future 

 course, or as to the true cause, of the observed changes. 

 Forty-three stations are available to Mr. Schott in the stuciv 

 of the magnetic declinations. A cursory examination shows 

 that the needle became stationary and then reversed its sec- 

 ular motion in the New England States towards the end of 

 the past century, in the Atlantic coast States to the west 

 and south early in the present, and in Mexico about the 

 close of the first third of the present century. In California, 

 Oregon, and Washington Territory it has not yet reached 

 its stationary point. 



Another important memoir by Schott gives the results of 

 the discussion of the photographic-magnetic record at Key 

 West, 1860-1866. After considering the normal monthly 

 averages, Schott takes the hourly and monthly means of all 

 the disturbances by which he understands all those individ- 

 ual readings that are rejected by "Peirce's Criterion." The 

 easterly disturbances exceed the westerly in every year but 

 two. The evidence of a connection of some kind between 

 the amplitude of the daily variation and the sun-spots is 

 quite strong. 



At the meeting, at Cassel, of the German Naturforscher 

 Gesellschaft, the following papers were read : Dr. Fromme 

 on Some New Magnetic Phenomena; Dr. Sobering on a New 

 Method of Employing the Induction of the Earth for the 

 Determination of the Magnetic Inclination. 



