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N a review of the scientific work of 1901, astronomy, as the oldest of the sciences, may fitly claim first mention, especially as it fell to the astronomers to make what was, on the whole, the most exciting discovery of the year. This was a new and brilliant star in Perseus, which appeared to spring into existence in a remarkably sudden manner. That portion of the heavens in which it was situated was photographed at Harvard on February 19, and no sign of it was to be detected on the plates when they were developed; yet only a day or two afterwards it was seen by Dr. T. D. Anderson, of Edinburgh, and by other observers as a star of between the second and third magnitude. The suddenness of its appearance was equalled by the rapidity with which its size varied, and this inconstancy, together with the extraordinary changes that took place in the character of its spectrum, provided astronomers with a theme for speculation, the resources of which are yet very far from being exhausted. In April a new comet, said to be the brightest since that of 1883, was discovered in the southern hemisphere by several observers. In May its tail, which at first was 10° in length and curved slightly to the south, split into three parts. On May 18th, there was an eclipse of the sun, the line of totality passing across the Indian Ocean through Sumatra, Borneo and New Guinea. The party from Greenwich selected their station in Mauritius, where the duration of totality was only three and a half minutes, and enjoyed the advantage of good weather. Other observers who took up their positions in Sumatra had a longer (six minutes') duration of totality, but were not quite so fortunate as regards weather.

In pure physics, perhaps the most interesting single achievement of the year was the experimental proof that light, as predicted by Maxwell and by Bartoli, exerts a mechanical pressure. Many observers have already attempted to detect this phenomenon, among them being Sir William Crookes, who at first thought he had succeeded in so doing with his radiometer, until it was found that his effect was many thousand times too great. Curiously enough, success was announced almost simultaneously in two different quarters, by Professor Lebedew, of Moscow University, in Europe, and by Messrs. Nicholls and Hull in America. The work of the latter observers appears to be the less precise of the two, for they do not claim that it does more than prove the existence of a pressure, not due to gas-molecules, of the nature and order of