Ii8 ROUGH WAYS MADE SMOOTH. 



five weeks before the earth came to the place of danger. 

 But no harm happened. In that year, and again in 1839, 

 the comet returned quietly enough, though in 1839 it 

 was not observed, being so placed that it was lost in the 

 splendour of the solar rays. In February, 1846, the comet 

 was again seen, this being the third return since its discovery 

 in 1826, or rather, since its recognition as a member of the 

 solar system, the eleventh since it was first seen by Montaigne. 

 At this time everything seemed to suggest that this comet, 

 unless our earth at some future time should absorb it, would 

 remain for a long time a steady member of the sun's comet 

 family. But only a few days after its detection in February, 

 1846, the comet was found to have divided into two, which 

 travelled side by side until both vanished from view with in- 

 creasing distance. In 1852 the companion comets re- 

 appeared, and again both continued in view till their motion 

 carried them beyond telescopic range. As the distance 

 between the coupled comets had increased from about 

 160,000 miles in 1846 to about 1,250,000 miles in 1852, 

 astronomers anticipated a most interesting series of observa- 

 tions at the successive returns of the double comet to the 

 earth's neighbourhood. Unfortunately, in 1859 the comet's 

 course carried it athwart a part of the sky illuminated by the 

 sun's rays, so that astronomers could not then expect to see it. 

 But in 1866 it was looked for hopefully. Its orbit had now 

 been most carefully computed, and many observers, armed 

 with excellent telescopes, were on the watch for it, with very 

 accurate knowledge of the course along which it might be 

 expected to travel, and even of its position from day to day 

 and from hour to hour. But it was not seen. Nor, again, 

 was it seen in 1872, when fresh computations had been made, 

 and observations were extended over a wider range, to make 

 sure, as was hopefully thought, that this time it should not 

 escape recognition. Could it have come, asked Herschel in 

 1866 and in 1872 the same question might still more per- 

 tinently be asked into contact or exceedingly close approach 

 to some asteroid as yet undiscovered ? or, peradventure, had 



