36 SPECIAL RESULTS IN THE URANOLOGICAL 



of the periodical variations of declination, inclination, and 

 force, has not as yet disclosed with certainty any influence 

 from the different positions either of the sun or of the nearer 

 moon.* The magnetic polarity of the earth does not shew 

 oppositions which relate to the sun, and are sensibly affected 

 by the precession of the equinoxes. ( 69 ) Only the re- 

 markable varying direction of the cone of light which 

 streamed from Halley's comet, and which Bessel observed 

 from the 12th to the 22d October, 1835, and sought to 

 interpret, had persuaded that great astronomer of the exis- 

 tence of a polar force, " of the action of a force differing 

 materially from gravitation or the ordinary attracting power 

 of the sun, since those portions of the comet which form 

 the tail experience the effect of a repelling force from the 

 body of the sun."( 70 ) The fine comet of 1744, which was 

 described by Heinsius, had also given occasion to similar 

 conjectures on the part of my deceased friend. 



The action of radiant heat is regarded as less problematical 

 than electro-magnetic agencies in space. According to 

 Fourier and Poisson, the temperature of space is the result of 

 the radiation of heat from the sun and all the heavenly 

 bodies, diminished by the absorption which the heat suffers 

 in traversing space filled with " ether." p 1 ) The " heat of the 

 stars" was spoken of on many occasions by the ancients 

 (the Greeks and Romans) ; ( 72 ) not merely because, accord- 



* [Since this passage was printed in the German original, the Philoso- 

 phical Transactions for 1849 have reached M. de Humboldt, containing a 

 memoir in which it is shown that the magnetic observations made in different 

 hemispheres, (at Toronto in Canada, and at Hobarton in Van Diernen Island), 

 concur in indicating that the terrestrial magnetism does undergo an annual 

 variation connected with the sun's position relatively to the earth. ED.] 



