340 



HISTORY OF SCIENCE. 



Poisson, and Barlow are perhaps the most eminent and successful of 

 the other investigators who contributed to the knowledge of magnetism. 

 The study of the variations, changes of intensity, dip, etc., of the com- 

 pass, besides the interest of the subject in itself, showed that the mag- 

 netic condition of the earth is connected with other phenomena which 

 present themselves on the large scale. It has been perceived that 

 the study of terrestrial magnetism may lead to the discovery of laws 

 and relations between the cosmical forces laws and relations of which 

 but an imperfect notion has yet been formed. Many are the observa- 

 tions that have been already made in various parts of the world, and 

 every scientific expedition adds to their number, for arctic and other 

 observers are always sent out with instruments for magnetic experi- 

 ments. Fig. 167 represents the use of the magnetometer in very high 

 latitudes. 



FIG. 167. A MAGNETIC OBSERVATION. 



