Page:The story of the comets.djvu/129

VII. Messier, however, saw it 4 times between March 26 and April 3.

On Nov. 10, 1805, Pons discovered a comet which was also found by Bouvard on the 16th. It had a nucleus, and the diameter of the coma on Nov. 23 was 6' or 7'. On Dec. 8 it was at its nearest to the Earth, and Olbers saw it without a telescope. Bessel and others calculated elliptic elements, and its identity with Montaigne's Comet was suspected, though no predictions as to when a return might be looked for again seem to have been ventured on.

On Feb. 27, 1826, an Austrian officer named Biela, at Josephstadt in Bohemia, discovered a faint comet which Gambart found on March 9. The observations extended over a period of 8 weeks, and it was soon recognized that not only was the comet's orbit an ellipse of moderate eccentricity; but that it was the same comet as those observed in 1772 and 1805.

In anticipation of its next return in 1832, investigations into the orbit were undertaken by Santini, Damoiseau, and Olbers. Santini found that the comet's period in 1826 was 2455 days, but that the attraction of the Earth, Jupiter, and Saturn would hasten its return by rather more than 10 days, and he accordingly fixed the next perihelion passage for Nov. 27, 1832. Damoiseau's investigations yielded much the same result. In 1828 Olbers called attention to the fact that in 1832 the comet would pass within 20,000 miles of the Earth's orbit, but that as the Earth would not reach that particular point till one month after the comet had passed it, no danger was to be apprehended. Astronomers were quite satisfied as regards this matter, but their confidence was not shared by "the man in the street" (to use the hackneyed modern phrase) who was greatly alarmed lest a collision should take place, and our globe suffer damage or destruction.