PHYSICS OF THE GLOBE. 55 



in the existence of abnormal electric currents produced near 

 the earth's surface by some change in atmospheric conditions. 

 These disturbances are themselves subject to daily and an- 

 nual fluctuations ; they are of a general and of a local nat- 

 ure, and can be detected instantly by simultaneous observa- 

 tions at several distant and several neighboring: stations. 

 The connection between the aurora and these disturbances 

 in the magnetic instruments is of a secondary nature to the 

 connection between the latter and the telluric electric cur- 

 rents. Since the lesser magnetic disturbances are almost 

 continually occurring, the traces of aurora are also almost as 

 frequent. (This agrees with the inference fairly deducible 

 from the numerous auroras recorded in the Monthly Weather 

 Reviews of the Army Signal Office.) 



The magnetic survey of Russia during 1871-75 by J. Smir- 

 now has been published in a translation from the original 

 Russian. Smirnow gives a comparison with Sabine's charts, 

 and shows where observations are now or soon will be most 

 needed. 



Hann contributes an instructive review and comparison 

 of the diurnal and annual periods in the magnetic declina- 

 tion at Russian and Australian stations. 



"The Absolute Direction and Intensity of the Earth's 

 Magnetic Force at Bombay, and its Secular and Annual 

 Variations," by Ch. Chambers, gives the result of magnetic 

 observations at Bombay since 1867. The magnetic elements 

 are all progressing in the positive direction. 



The Coast Survey Report for 1874, published during this 

 year, contains valuable memoirs by Schott on secular 

 change of magnetic declination in the United States, and 



^J cj j 



a discussion of the results of the self-recording instruments 

 at Key West, 1 860-1 8G6. 



EARTH CURRENTS. 



At a recent social meeting of the London Society of Tele- 

 graph Engineers, Mr. Saunders, of the Eastern Telegraph 

 Company, exhibited some diagrams showing some results 

 of simultaneous observations of the earth currents observed 

 at both ends of the broken cable between Suez and Aden. 

 A striking coincidence is seen between the currents observed 

 on the two sections of the cable. 



