424 POPULAR SCIENCE MONTHLY. 



SCIENCE IN 1901.* 



"jTN 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 Persens, which ap- 

 peared 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 5^et 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 ISth, 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 se- 

 lected 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 al- 

 ready attempted to detect this phenomenon, among them being Sir Wil- 

 liam 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 si- 

 multaneously in two different quarters, by Professor Lebedew, of Mos- 

 cow University, in Europe, and by Messrs. Nicholls and Hull in Ameri- 

 ca. 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 mag- 



* From the London Times. 



