Xll CONTENTS. 



ABT. PACK 



44. Reasons for believing that Terrestrial Magnetism does not 



reside, in any important degree, in the Earth's surface . 101 



45. Attempt to explain Terrestrial Magnetism by the action of 



a magnet of small dimensions but of very great power, near 

 the center of the Earth 103 



46. Attempt to explain Terrestrial Magnetism by the action of 



two magnets within the Earth 106 



47- Gauss's more general explanation of Terrestrial Magnetism 

 by supposing that the red and blue magnetisms are dis- 

 tributed irregularly through the Earth .... 107 



48. Incidental introduction of Laplace's Coefficients (not further 



used in this Treatise) . . . . . . . .115 



49. Continuation . of Gauss's investigation; application in a 



numerical form , . .117 



SECTION yn. 



DISTURBING FORCE PRODUCED ON 4 SMALL COMPASS-NEEDLE BY A 

 LARGE MAGNET, IN VARIOUS POSITIONS: AND COMPOSITION OP 

 THIS DISTURBING FORCE WITH TERRESTRIAL HORIZONTAL FORCE. 

 Articles 5055. Pages 122129. 



50. The disturbing magnet is horizontal; its center is broadside- 



on to the center of the compass ; to find its effect at different 

 distances and elevations 122 



51. The disturbing magnet is end-on to the compass; first, in the 



horizontal plane ; secondly, in an inclined plane, the axis of 

 the magnet still directed to the compass . . , . }23 



52. The disturbing magnet is horizontal; it is directed end-on 



to the vertical axis of the conipass, and is not necessarily at 

 the same elevation as the compass . . , . . 124 



53. The disturbing magnet is vertical . . . . . .126 



54. The disturbing magnet is in the horizontal plane which passes 



through the compass, but is inclined at any angle to the line 

 joining the centers of the magnets 127 



55. Composition of the disturbing force in the horizontal plane 



with the terrestrial horizontal force 128 



SECTION VIII, 



ON TRANSIENT INDUCED MAGNETISM IN SOFT IRON AND IN MAGNETS. 

 Articles 5674, Pages 130167. 



56. Definition of Soft Iron, and criterion of the magnetic differ- 



ence between Soft Iron and Magnetized Steel . . . 130 



