44 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



applied by Backlund to the computation of the movements of 

 the asteroid Iphigenia. The original method consists in in- 

 tegrating the differential equations of perturbations, accord- 

 ing to analytical methods, instead of by mechanical quad- 

 ratures ; Gylden's idea appears to lead to as simple forms 

 of computation as the older methods, but possesses several 

 great advantages, especially in the checks upon the accuracy 

 of the computation at every step of the process. By means 

 of analytical formula? developed by him some years ago as pre- 

 liminary to the present work, he is able to express the co- 

 ordinates as well as the sines and cosines of the co-ordinates 

 of the perturbed bodies in rapidly converging series. Dr. 

 Backlund, in applying Gylden's method to the computation 

 of the special perturbations of Iphigenia, has taken account 

 only of the disturbances introduced by Jupiter during three 

 semi-revolutions of the asteroid. He divides the orbit of the 

 planets into sixteen equiangular portions of twenty-two de- 

 grees each, for each of which the perturbations are independ- 

 ently computed. Vierteljahrssclir. Astron. Gesellsch., X., 36. 



galle's tatii of the meteor of JUNE 17, 1S73. 



The orbit of the bright meteor observed in Austria and 

 Germany on the 17th of June, 1873, has been carefully inves- 

 tigated by Professor Galle. Having satisfied himself that 

 the end of the visible path of the meteor was not far from 

 Zittau, he made a special examination of that region, and 

 gathered many observations which enabled him to fix the 

 actual position of the meteor at the time of its disappear- 

 ance, and was even able to gather some of those fragments 

 which reached the earth, although their actual fall was not 

 observed by any one, and the connection of the supposed 

 fragments with the original mass is subject to some doubt. 

 In the computation of the orbit, Professor Galle proceeded 

 according to the method elaborated by him as most appro- 

 priate to such cases, as follows : 



Having determined definitively the exact position of 

 the end of the orbit, each observer's observation then en- 

 abled him to determine the apparent plane of motion, the 

 intersection of which planes determined the position of the 

 path followed by the body. Among the thirty-three excel- 

 lent observations which he was able to use in his study, only 



