RETURN OF THE GREAT COMET OF 1264. 155 



Between the years 1843 and 1847, Mr. Hind of London 

 investigated the question of identity anew, and he con- 

 cluded that the comets of 1264 and 1556 were very 

 probably the same, and that a return to perihelion might 

 be expected about the middle of the nineteenth century. 



M. Bomme, of Middleburg, in the Netherlands, has 

 computed the effects that will be produced on the period 

 of the comet's return by the united attraction of the 

 planets. With Dr. Halley's elements it was found that 

 at the time the comet was visible in 1264, it was moving 

 in an ellipse, with a periodic time of 112,469 days, or 

 308 years; but perturbations, owing to planetary at- 

 traction, quickened the return of the comet by no less 

 than 5903 days, so that it was in perihelion in April 

 1556, and at that time the revolution corresponding to 

 the elliptic arc described was 112,943 days. Starting 

 again from this epoch, M. Bomme ascertained that the 

 next revolution should occupy 111,146 days, bringing 

 the comet to its perihelion on the 22d of August, 1860, at 

 which time the revolution will be 113,556 days. 



Employing Mr. Hind's elements, it was found that in 

 1264 the ellipse described by the comet had a period of 

 110,644 days, or 302.922 years, and that planetary dis- 

 turbances expedited its return by 4077 days. At the time 

 it was visible in 1556, its mean motion corresponded to 

 a period of 308.169 years. The present revolution 

 should be shortened by perturbations 3828 days, or 

 10.48 years, and the comet should again reach its peri- 

 helion on the 2d of August, 1858, the revolution belong- 



