606 Foreign and Miscellaneous Intelligence. 



trary positions of the vertical circle. This method was, accordingly, 

 adopted, and the following observations were made. 



In the bota- 

 In the town, uic garden, 



The vertical circle having Ma *J 18 * Jun^a isas. 



its face East. . . . 71 5 f/ 7 5 70 55'.75 



53. 00 54. 75 



West .... 70 11.0 71 52.00 



15.5 71 54.25 

 After the inversion of the poles 

 The vertical circle having 



its face East .... 72 23'.00 70 7'.0 



19.00 6.0 



West ... 70 4. 50 72 11. 5 

 70 4.75 15.0 



Results ... 71 7' 49" 71 17' 2" 



Mean between the two . 71 12' 25" 

 iii. Intensity of the Magnetic Force. Messrs. Humboldt and 

 Hansteen having ascertained the intensity of the magnetic force at 

 Berlin, that which obtains on the magnetic equator being, as usual, 

 considered as unity, nothing was required but to compare the mag- 

 netic forces at Berlin and at St. Petersburgh by the same instru- 

 ments, and by the same methods. For this purpose, M. Erman 

 employed two needles horizontally suspended. The first needle, 

 which shall be called A, is a small cylinder of the best tempered 

 steel that could be procured, in figure and dimensions exactly like 

 the cylinders used by M. Hansteen for determining the same inten- 

 sity in western Europe, This needle had been magnetized to satu- 

 ration about a year before, and had not been retouched since, as it 

 was to be presumed that the magnetic state that had been induced 

 after the lapse of a year would be longer preserved than any which 

 might be produced by retouching the needle. The second needle 

 (B) is a bar of six inches in length, which was tempered and mag- 

 netized by Coulomb. This is the same which has been used by 

 M. Humboldt for comparing the intensities in Europe with that on 

 the magnetic equator, arid it is well known that this needle hardly 

 changed its intensity at all during the whole course of his travels. 

 The times of the oscillations were observed by a chronometer beating 

 five times in two seconds. The time was noted for every ten oscil- 

 lations, and a hundred of them were counted at each time. The re- 

 sult has been deduced by the method of minimum squares, and by a 

 reduction of the observed times of the oscillations to that of an 

 infinitely small oscillation, by means of the observed elongations of 

 the first and the hundredth oscillations. 



Duratio n of an Oscillation. 



At Berlin. At St. Petersburgh. 



Of needle A , . 3". 0990 3". 2086 



Of needle B 4". 6161 4". 7852 



