COMET OF 1889-1896-1903. 



287 



As TO Identity with Comet 1770 (Lexell). 



40. Lexell's comet underwent its notable disturbance in the 

 year 1779 and, moreover, this disturbance took place in that 

 part of Jupiter's orbit in which Comet 1889 (Brooks) suffered 

 its great change of elements in the year 1886. Between these 

 two appulses there intervened a period of 107 years, which 

 period must be accurately accounted for in order to establish 

 the identity of these two remarkable bodies. But, assuming 

 the substantial correctness of the present investigation, we can- 

 not directly account for these years. For the period of Comet 

 1889 (Brooks) in 1883, or previous to its disturbance, has been 

 shown to be 29.22 ± 0.03 years, which is not an aliquot part 

 of 107. Hence, unless in the intervening years the comet suf- 

 fered other and marked disturbances in its orbit, the entire 

 question as to the identity between the bodies disappears. 



An investigation shows us that such disturbances may have 

 taken place during this interval, but leaves us uncertain as to 

 the resulting changes in the orbit. Elements VI represent the 

 motion of the comet previous to 1883 and, assuming for the 

 moment that the comet suffered no perturbations before that 

 date, we can find the approximate dates at which the comet 

 may have approached sufficiently near to Saturn or to Jupiter 

 to have had its motion appreciably disturbed. 



41. Approaches to Saturn. The orbits of the two bodies, 

 Saturn and the comet, intersect in longitudes 79° and 298° ; 

 the comet and Saturn being in these respective longitudes at 

 the times given in the following table : 



Table XVII. 



