observers, suspecting, and with good reason, that a well-kept watch would reveal unknown wonders in the depths of space, undertook to search for other planets. Had photographic plates or charts then been part of the equipment of an observatory, the work would have been easy, and the reward certain. But plates and star-charts were not known; and the twenty-four workers laboured and toiled in vain. An outsider carried off first honours on the first day of the century—Piazzi of Palermo, who had visited Slough, had talked with Herschel and his sister, and perhaps drawn a breath of inspiration from them and their surroundings. The beaten twenty-four astronomers did not retire from the field. Two years later, Dr. Olbers, of Bremen, discovered another asteroid, Pallas; and two years later still, Harding, in the same neighbourhood, discovered a third, Juno. Olbers, wisely using imagination in the pursuit of science, came to the conclusion that these small bodies were pieces of a planet which had burst or exploded, and that other pieces would be found floating about in space. He acted on the idea, and rediscovered Piazzi's Ceres, which had been lost again, as well as a fourth asteroid, Vesta. Then the hunt for more pieces of the disrupted planet ceased, till, about forty years later, it again received a fresh impetus from Hencke's discovery of Astræa, and was continued by Mr. Hind at the Regent Park Observatory in London, and others, with such success that floating pieces have been netted by hundreds, grumbled at as nuisances, and assigned the honour of having been thrown off direct by the sun himself, not blown into space by a disrupted planet. One of these pigmy planets was named Lucretia, after
