154 SCIENCE IK SHORT CHAPTERS. 



The question now discussed by astronomers is whether they 

 are connected with any other comet, and, if so, with which 

 comet ? 



In the Monthly Notices of the Royal Astronomical Society, 

 published October 24th last, is a very interesting paper by 

 Professor Herschel, on " Observations of Meteor Showers," 

 supposed to be connected with " JBiela's comet," in which he 

 recommends that " a watch should be kept during the last 

 week in November and the first week in December," in order 

 to verify " the ingenious suggestions of Dr. Weiss," which, 

 popularly stated, amount to this viz. that a meteoric cloud 

 is revolving in the same orbit as Biela's comet, and that in 

 1772 the earth dashed through this meteoric orbit on Decem- 

 ber 10th. In 1826 it did the same, on December 4th ; in 

 1852 the earth passed through the node on November 28th, 

 and there are reasons for expecting a repetition at about the 

 same date in 1872. 



The magnificent display of the 27th has afforded an impor- 

 tant verification of these anticipations which become especially 

 interesting in connection with the curious history of Biela's 

 comet, which receives its name from M. Biela, of Joseph- 

 stadt, who observed it in 1826, calculated its orbit, and con- 

 sidered it identical with the comets of 1772, 1805, etc. It 

 travels in a long eccentric ellipse, and completes its orbit in 

 2410 days about 6f years. It appeared again, as predicted, 

 in 1832 and 1846. 



Its orbit very nearly intersects that of the earth, and thus 

 affords a remote possibility of that sort of collision which has 

 excited so much terror in the minds of many people, but 

 which an enthusiastic astronomer of the present generation 

 would anticipate with something like the sensational interest 

 which stirs the soul of a London street-boy when he is madly 

 struggling to keep pace with a fire-engine. 



The calculations for 1832 showed that this comet should 

 cross the earth's orbit a little before the time of the earth's 

 arrival at the same place ; but as such a comet, travelling in 

 such an orbit, is liable to possible retardations, the calculations 

 could only be approximately accurate, and thus the sensational 

 astronomer was not altogether without hope. This time, how- 

 ever, he was disappointed ; the comet was punctual, and cross- 

 ed the critical node about a month before the earth reached it. 



As though to compensate for this disappointment, the 

 comet at its next appearance exhibited some entirely new 



