( 643 ) 



orbit found for 1892 and the computation of the perturbations Avhich 

 had been based on them were \ery nearly correct. 



The observations in 1899 and 1900 furnished me with sufiicient 

 material to apply to the elements such small corrections as brought 

 the remaining diflerences between the predicted and the observed 

 positions within the limits of ordinary errors of observation. The 

 system of elements obtained thus, which satisfied both the appearance 

 of 1892—93 and that of 1899—1900 and which in my "Deuxième 

 Mémoire" p. 78 has been recorded as "Système VU", must naturally 

 furnish the basis for further investigations. Therefore I shall give 

 it here in its general features. 



System VII. 

 Epoch 1899 June 11.0 mean time of Greenw. 



Osculation 1899 September 9.0 „ „ „ 

 M, =z 22661" 3264 

 11= 516" 188791 

 log a= 0.558 1320.0 

 <pz= 24° 17' 23"54 

 e= 0.4113532 

 t= 20° 48' 9"84 

 jt = Wo 48 38.06 1899.0 

 ta = 331 43 18.24 



iz= 20 48 10.29 j 

 .-r = 345 49 28.27 1900.0 

 ^ = 331 44 8.95 ) 

 Although the corrections which had to be applied to the elements 

 in consequence of the new observations were small, I immediately 

 after the publication of those researches resolved to repeat the compu- 

 tation of the perturbations between 1892 and 1900 with the new- 

 elements and to extend it to all the planets of which the disturbing 

 effect could not a priori be neglected as being insensible. This 

 elaborate investigation, which necessarily required a new discussion 

 of the two appearances of the comet, was however only partly 

 finished when in 1905 the preparation for the third appearance had 

 to be taken in hand. 



I have then started from system VII, which though not perfect, yet 

 satisfied all practical demands. I did not venture, however, to use 

 those elements without more for the computation of the places at 

 the return of the comet in 1906. It is true that the disturbing planets, 

 especially .lupitev, whose influence is by far the greatest, remained 

 at a considerable distance during the entire revolution of the comet, 

 yet the feeble light of the comet in 1899—1900 and the difficulty 



