326 Prof. Hansteen on the Intensity of Magnetism 



The following additional observations have been sent us by 

 Professsor Hansteen : 



Carlscrona, - 735 



Breslau, - - - - 741 



Stockholm, ... - 815 



Hernosand, - - x - - 850 



These various results have been laid down on a map by 

 Professor Hansteen ; but, as they occupy only a small part of 

 Europe, we do not think it necessary to copy his chart. Any 

 of our readers, however, may easily lay down, upon a map of 

 Europe, the lines of equal magnetic intensity, either from the 

 above tables, or more simply by the following directions: 



1. The line of 750, or the line in which 750 seconds are 

 required for the performance of 300 oscillations, passes one- 

 fourth of a degree to the south of Paris and Rheims, and 

 one-third of a degree to the south of Gotha and Gaslin. * 



2. The line of 775 passes about one-third of a degree south 

 of London, and through Amsterdam and Lvbeck. 



3. The line of 800 passes about the fifth of a degree north 

 of York; Spomng in Jutland, and Falkenberg in Sweden. 



4. The line of 820 passes through Edinburgh, and a little 

 to the south of Christiansand in Norway, and Carlstadt in 

 Sweden. 



5. The line of 865 passes through Hirdal in Norway. 



As the lines are almost equidistant, and nearly parallel, all 

 the intermediate ones may be readily inserted. 



Professor Hansteen has added the following very interest- 

 ing table, containing the observed dip of the needle, and the 

 computed magnetic intensity in various parts of the world, 

 that of the equator being unity or 1.0000. A similar table 

 was printed in Professor Hansteen 1 s paper, in Poggendorffs 

 Annalen der Physik, but the column of intensity had been 

 wrong computed for all the places in the north of Europe, 

 and we are happy to be able, through Professor Hansteen's 

 kindness, to present our readers with a corrected copy. 



» The line of 740, of which only one point has been determined, passes 

 through Breslau. 



