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Dr. G. Nenmayer. 



and terrestrial magnetism. Bat apart from that, a magnetic survey 

 of the Antarctic region is of the greatest importance from other- 

 points of view. As, since the time of Ross, no fresh observations on 

 the values of the magnetic elements have been made, we are entirely 

 ignorant of the values of the secular variation south of 50° latitude, 

 data so much needed for the construction of reliable magnetic charts. 

 Of the situation of the southern magnetic pole, and of its motion 

 during the last fifty years, we are equally ignorant. The situation 

 of the southern extremity of tbe earth's magnetic axis and its motion 

 throughout half a century are extremely important according to 

 Gauss's theoretical deductions. All computations, however intri- 

 cate, must prove incomplete, and inadequately reward the immense 

 amount of labour bestowed upon them, unless reliable values of the 

 magnetic elements are first obtained, for which purpose a reduc- 

 tion to a certain epoch by means of secular changes is indispensable. 

 But not merely for theoretical purposes is such value to be put upon 

 the knowledge of the magnetic character in the Antarctic, but also 

 for the construction of reliable magnetic charts for use in naviga- 

 tion. Certainly the studies of Carlheim-Gyller skjold and Yan 

 Bemmelen deserve great credit from a theoretical point of view, 

 but they also cannot be carried to perfection unless we have a sound 

 knowledge of the magnetic character of the South Polar region — 

 at least as sound as that of the North Polar region. In the time 

 of Ross, the magnetic Observatory at Hobart served as a safe 

 basis for observations on terrestrial magnetism, and now the excel- 

 lent Observatory at Melbourne may be turned to a similar account. 



Well as the mathematical theory of terrestrial magnetism has 

 been developed, of the physical theory of that mysterious natural 

 force, we are as yet in perfect ignorance. This defect is certainly 

 to some considerable degree caused by the deficiency of our know- 

 ledge in higher latitudes. It looks as if the magnetic character of 

 the South Polar region were such as would afford every facility for 

 a sound investigation when brought into comparison with the 

 magnetic conditions of the North Polar region. A glance at the 

 map shows how entirely different is the distribution of the magnetic 

 force (action) in the two polar regions. In the south there is to be 

 noticed the interesting fact that the two foci of total intensity are 

 both situated on the side towards the south of the Australian 

 continent, and nearly on the same meridian. 



The magnetic action which makes itself manifest by magnetic 

 storms or disturbances reaches its highest degree likewise south of 

 the Australian continent, whereas to the south of South America 

 these disturbances become very scarce and of a character in point 

 of magnitude similar to those of the temperate zones. This was 

 most strikingly proved by the observations in Orange Bay and 



