A. MATHEMATICS AND ASTRONOMY. 21 



considerable doubt, since no one was ever able to confirm the 

 observations of Herschel. In 1847 Lassell discovered two 

 interior satellites, which were, however, different from those 

 which Herscbel suspected ; and since that day the four prob- 

 lematical satellites of Herschel have been generally discarded 

 by astronomers. Professor Holden now brings testimony to 

 the high excellence of HerschePs observations, as, by com- 

 puting backward, he has shown that probably this distin- 

 guished astronomer actually observed the two interior satel- 

 lites of Lassell (named by him Ariel and Umbriel) ; but that 

 he was unfortunately prevented from identifying them as 

 satellites because his telescope could not show them on two 

 successive nights. The extreme difficulty of observing these 

 objects makes us wonder at the marvelous skill and patience 

 manifested by the elder Herschel in this laborious research, 

 which was carried on by him from 1787 to 1810. Bull. 

 Phil. Soc. Washington, Appendix IV. 



ORIGIN OF AEROLITES. 



During the last two or three years the discovery of ener- 

 getic forces of eruption on the sun has demonstrated the oc- 

 casional occurrence of convulsions so violent that they may 

 suffice to project molten and gaseous matters to distances 

 beyond the sphere of the sun's attraction. The existence of 

 such forces and the evidence which the microscope affords 

 that aerolites have had their origin among mineral masses in 

 a state of fusion, if not of vapor, combine to support the 

 theory, formerly entertained by other writers and recently 

 announced very definitely by Mr. Proctor in England and 

 Professor Kirkwood in America, of the astro-meteorological 

 hypothesis of the origin of meteors and meteorites. .Report 

 Brit. Assoc, 1873, 400. 



THE GREAT COMET OF 1684. 



The investigation of the great comet of 1684 forms the 

 subject of the inaugural dissertation of Professor JSTeugebauer 

 of the University of Breslau. This comet belongs to those 

 which, on account of the close approximation of their orbits 

 to the earth's orbit, have attracted the attention of Professor 

 Schiaparelli as worthy of scrutiny in connection with shoot- 

 ing-stars. The only accurate observations of the comet of 



