THE RETURN OF HALLEY’S COMET.2 
[With 4 plates. ] 
By W. W.- CAMPBELL, 
A celestial event of unusual interest is expected soon—the return 
of Halley’s comet. Its appearance will be welcomed as the coming 
of a faithful friend, whose visits to the sun’s domains have repeated 
themselves every seventy-seven years since long before the time of 
Christ. Any day may bring the news that this object has been redis- 
covered, near the northern edge of the constellation Orion; but we are 
really not expecting the announcement until the last third of 1909. 
The comet will be faint when first seen, for we know quite closely 
where to look, and the most powerful photographic telescopes in 
several countries are periodically “ prospecting ” the critical region. 
Why is this comet known as Halley’s? The incidents connected 
with its christening form an interesting chapter in the early history 
of astronomy. A brilliant comet appeared in 1682, when Halley 
was a young man, in England. This was Halley’s comet, but his 
name was not connected with it until much later, as we shall explain. 
Halley’s friend, the great Sir Isaac Newton, had but recently (about 
1670-1680) discovered the law of gravitation, and had proved that 
a comet or other body completely subject to the sun’s attraction 
must move in an ellipse around the sun. Newton was of a retiring 
disposition and took no steps to make known his immortal discov- 
eries. * Halley, on the contrary, was a man of action. These charac- 
teristics of the two men are apparent from their portraits. The 
manuscript copy of Newton’s Principia was intrusted to Halley, and 
the latter, in the absence of other funds available for the purpose, 
published the book in 1686, at his own expense, though he was a man 
of small financial means. This act alone stamps Halley as worthy 
of our homage. 
Halley realized the wonderful import of the great law, certainly 
as early as 1685, but his opportunity for systematic work in astron- 
“Reprinted by permission from Publications of the Astronomical Society of 
the Pacific, San Francisco. Vol. 21, No. 128. October, 1909. 
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