95 
x 88 o.] Edmund Halley . 
beginning of 1759 — the first prediction of the return of a 
comet. 
This comet, as is well known, actually passed its perihe- 
lion on March 12th, 1759, just one month before the time 
calculated by Clairaut, Lalande, and Madame Lepaute ; and 
again on November i 5 * 95 > I ^ 35 > within five days of Rosen- 
berger’s elaborate calculation. We now await the next 
advent of Halley’s comet in 1909-10, its perihelion passage 
being fixed by the late Count G. de Pontecoulant (as com- 
municated by him to the Paris Academy of Sciences in 
1864) to May 23.87 (Paris time?), 1910 ; it having been last 
glimpsed by Dr. Lamont with the Munich refraCtor on 
May 17th, 1836. (See 44 Nature,” February n, 1875, p. 286.) 
An account of his next research is given by K., in a paper 
on the 44 Early History of Magnetism,” in “ Nature,” April 
27, 1876, p. 523, as follows : — 44 In 1683 Halley presented a 
paper of great importance to the Royal Society of London, 
entitled 4 A Theory of the Variation of the Magnetical 
Compass.’ In this communication he states that the 4 de- 
flection of the magnetical needle from the true meridian is 
of that great concernment in the art of navigation that the 
negleCt thereof does little less than render useless one of 
the noblest inventions mankind ever yet attained to, and 
gives as the result of 4 many close thoughts ’ the following 
explanation of the variation of the compass : 
‘ 4 4 The whole globe of the earth is one great magnet, 
having four magnetical poles or points of attraction, near 
each pole of the equator two ; and in those parts of the 
world which lie near adjacent to any one of those magnet- 
ical poles, the needle is governed thereby, the nearest pole 
being always predominant over the more remote. He re- 
marks that the positions of these poles cannot as yet be 
exaCtly determined, from want of sufficient data, but con- 
jectures that the magnetic pole which principally governs 
the variations in Europe, Tartary, and the North Sea is 
about 7 0 from the North Pole of the earth, and in the meri- 
dian of the Land’s End ; whilst the magnetic pole which 
influences the needle in North America, and in the Atlantic 
and Pacific Oceans, from the Azores westward to Japan, is 
15 0 from the North Pole, and in a meridian passing through 
the middle of California. The variation in the South of 
Africa, in Arabia, Persia, India, and from the Cape of Good 
Hope over the Indian Ocean to the middle of the South 
Pacific, is ruled by the most powerful of all these magnetic 
poles, which is situated 20° from the South Pole of the 
earth, and in a meridian passing through the island of 
