1 8 THE POPULAR SCIENCE MONTHLY 



attraction of other comets or even of some planet, too far removed from 

 the sun to be even perceived. It should be remembered that nothing 

 was known at this time of Uranus and Neptune. The actual time of 

 perihelion passage was March 13, just within the limit. 



The history of its discovery is interesting. Though astronomers 

 everywhere were looking forward with great interest to the event, the 

 most elaborate attack was made at Paris. This was planned by De 

 Lisle, but the work of searching for the body fell to Messier, whose 

 name is familiar to astronomers everywhere in connection with the 

 discovery of numerous comets, nebulae and clusters. He had a genuine 



LCUuk. 



The Path of Halley's Comet and its Conjunction with the Earth's Okbit. 



passion for this class of work, but no taste whatever for theoretical re- 

 search. At this time he was living in the house of De Lisle, who 

 seemed to think that he had a property right in Messier's observations, 

 which Delambre tells us he hoarded as a miser does his wealth, neither 

 using them himself nor allowing any one else to do so. 



De Lisle planned a systematic siege of the stronghold. Assuming 

 limits which he believed wide enough for the purpose, he prepared 

 charts on which lines were drawn for convenient dates, the supposition 

 being that the comet would be found somewhere on the line. Night 

 after night for eighteen months, Messier carried on the siege until, 

 finally, on January 21, 1759, he was rewarded with his first sight of 

 the comet. It was doubtless humiliating to all concerned to learn that 

 on Christmas eve, previous, the comet had been seen by a peasant named 

 Palitzsch. Delambre states that he saw it with the naked eye, without 

 previous knowledge of its existence, but this is not the true history. 

 The account given by Palitzsch is quite different. He states that he 

 was engaged in observing the variable star, Omicron Ceti, with his nine- 

 foot tube, and that he found between Delta and Epsilon Ceti a nebu- 



