THE EXPECTED RETURN OF HALLEY'S COMET 547 



Lo ! the reputed messenger of fate, 

 Arrayed in glorious but tremendous state, 

 Moves on majestic o'er the heavenly plane, 

 And shakes forth sparkles from its fiery train. 



Ye sons of science, from your high abodes, 

 Descry its oblique path, and mark its nodes, 

 Explore with what velocity 'tis hurled, 

 And how exact its period round the world ; 

 Now, now, in this delightful work engage. 

 Pursue the steps of the sagacious sage, 

 And be this wiser than the former age. 



The apparition of 1759 was not very remarkable for its 

 brilliance. The comet was, however, distinctly visible to the 

 naked eye, and had a long thin tail. 



Before it returned again in 1835, the science of perturba- 

 tions had made great strides. Many mathematicians engaged, 

 in this work, the most successful being Rosenberger and de 

 Pontecoulant, who both predicted the time of perihelion 

 correctly within a very few days. The work of the former 

 was on more rigorous lines, and he took account of a few 

 minute disturbances that were neglected by the other. 



The comet was first seen by M. Dumouchel, Director of the 

 Observatory of the Roman College, on August 5, 1835. It 

 passed its perihelion on November 16, and remained in sight 

 till the following May, its changes of appearance being carefully 

 followed by astronomers all over the world. Though not 

 equal in splendour to the greatest comets of the nineteenth 

 century, such as Donati's in 1858, or those of 181 1, 1843, l882 > 

 it was nevertheless an extremely interesting object, from the 

 rapid changes which it underwent from night to night. In 

 this respect it seems to have closely resembled comet More- 

 house, which has just passed out of reach of Northern observers, 

 but is still under observation in the Southern Hemisphere. The 

 nucleus in each case appeared to be in a state of great activity, 

 and ejected streams of matter in various directions with a 

 violence that has been compared to a volcanic outburst. These 

 streams are at once repelled by the sun, the repulsive force 

 being either of an electrical nature or being simply the action 

 of light on very finely divided matter. The main tail is directed 

 almost exactly away from the sun, but there are a number 

 of lateral tails or brushes, making various angles with this. It 



