Magnetic Observations. 



235 



differences, between the observations and predictions, will give an 

 idea of the present degree of progress in this department of scientific 

 research. 



While avoiding, in this paper, any lengthy discussion of the nature 

 of the energy of space; of force per se; as the cause of magnetic ac- 

 tion; it is proper to call to mind some of the phenomena which, from 

 their close connection with this subject, have made the expressions 

 Terrestrial Magnetism and Cosmical Magnetism appear to be the 

 proper titles for this branch of research. 



The telescopic study of the Sun has shown that enormous disturb- 

 ances of the solar atmosphere occur at times. Magnetic observations 

 made upon the Earth, at moments identical with those of the solar 

 disturbance, show that such solar action is synchronous with intense 

 magnetic action at terrestrial stations. While we cannot prove that 

 the solar disturbance is the cause of the magnetic disturbance upon 

 the Earth, yet there appears to be a magnetic bond between the Sun 

 and the Earth, through the apparently open intervening space, with a 

 probability that the Sun is more nearly the centre of the origin, and 

 the Earth the location of a resultant of the magnetic disturbance. 



It is from this phenomenon that we obtain the mental concept of a 

 primary or Solar magnetism, and a secondary or Terrestrial magnetism. 

 It is a logical sequence of the instantaneous communication through 

 space, of this mysterious influence, that there must be an energy and 

 magnetism in space or Cosmical Energy or Cosmical Magnetism; an 

 atmosphere of force, which probably controls both the magnetism of 

 the Sun and its planets. 



Hence by terrestrial magnetism is meant the magnetic atmosphere 

 of the Earth; and "magnetic observations " are observations of the 

 local action of this so-called atmosphere upon matter; the record 

 giving an account of the visible movements of sensitively arranged 

 magnets, or matter sensitive to magnetism, under the influence of 

 this assumed magnetic atmosphere . The " magnets " of the magneto- 

 meters, or declinometers, are indices from whose movements we are 

 able to form some opinion of the invisible, magnet- making Energy, 

 the powers of which we seek to understand from its functions, by 

 gauging, measuring or weighing its action on matter sensitive to its 

 influence. 



In every case the observations at any particular locality afford only 

 what may be called a knowledge of the local magnetism; or, more 

 properly — for we have no brief name for it — the condition of the 

 cosmic magnetic energy, under the local influences. 



