Prof. Hansteen on the Intensity of Magnetism, c$-c. 323 



Art. XXVIII. — Observations on the Intensity of Magnetism 

 in diffei-ent parts of the EariKs Surface. By Christian 

 Hansteen, Professor of Astronomy in the University of 

 Norway. 



Professor Hansteen of Christiana, to whose discoveries and 

 writings we owe so much of our present information respect- 

 ing the magnetism of the earth, has been so kind as to trans- 

 mit to us the results of his most recent experiments upon this 

 subject, and also a corrected and more complete copy of his 

 chart of the magnetic lines. 



In order to determine the intensity of magnetism at differ- 

 ent places, and consequently the direction of what he calls 

 the isodynamical magnetic lines, or the magnetic lines of 

 equal intensity, he had a magnetic needle of a cylindrical 

 form, constructed with great care. This needle he entrusted to 

 various philosophers, who counted the time in which three 

 hundred horizontal oscillations were performed, in various 

 parts of Norway, Sweden, Denmark, Prussia, Holland, 

 France, England, and Scotland. The greater number of 

 these were made by Professor Hansteen himself, many of 

 them by M. Naumann, several by M. Erichsen, and a con- 

 siderable number by Professor Oersted of Copenhagen, when 

 he was travelling in England in 1823. Those which were 

 made by this last philosopher in Edinburgh on the 4th July, 

 and at which we had the pleasure of assisting, were perform- 

 ed in the field behind Coates Crescent, and nearly at the in- 

 tersection of Walker Street and Melville Street. These pos- 

 sess considerable interest, as being the most westerly of all 

 that have yet been made. 



The following table contains the result of these observa- 

 tions, the first and second columns containing the latitude of the 

 place of observation, and its longitude from Fcrroe ; and the 

 third the numher of seconds in which 300 oscillations are per- 

 formed by the suspended needle. 



