THE PROGRESS OF SCIENCE. 



109 



plates have piven poor results in day- 

 light, and Professor Niplier recommends 

 Cramer's 'oro\\n' plate. 



The new star in Perseus, Avhich has 

 now waned in the sky, and in the mem- 

 ory of most people, is still an object of 

 discussion among astronomers. Our 

 readers will remember Professor New- 

 eomb's recent article on variable stars 

 and the difliculties in the way of ac- 

 counting for their periodicity. In the 

 extreme case of new stars the difficulty 

 is greatest. The theories of an out- 

 burst from the molten interior and of 

 collision might account for the appear- 

 ance of the star, but do not explain its 

 rapid waning, nor are they in accord 

 with spectroscopic determinations. Pro- 

 fessor Seeliger's theory tliat a dark star 

 passes through a swarm of meteors is 

 I lie most satisfactory form of hypoth- 

 eses, but leaves room for the ingenious 

 suggestion, recently made by the great 

 astronomer, M. Janssen, before the 

 Paris Academy of Sciences. He points 

 out that the apparent absence of oxy- 

 gen from tlie sun may be due to its 

 existence in some dissociated condi- 

 tion that the spectroscope would not 

 reveal. This condition may be owing 

 to a very high temperature, and when 

 this becomes low enough to allow oxy- 

 gen to assume its common form, and 

 so to unite with hydrogen, there would 

 ensue, as a result of the combustion, a 

 great increase in heat and light, wliich 

 would account for the brilliancy of a 

 new star. The rapid decrease in bril- 

 liancy which follows would be accounted 

 for by the formation of an atmosphere 

 of vapor, which would serve as a grad- 

 ually increasing obstacle to radiation 

 from the star. A corollary of M. Jans- 

 sen's supposition is that our own sun 

 may at any time reach this transition 

 point for oxygen and blaze out into a 

 fury of heat and light that would scorch 

 all life off the face of the earth. It is, 

 however, a pleasant feature of solar ca- 

 tastrophes that astronomical time is 

 measured by millions of years. 



One of the most interesting total 



eclipses of the sun, wliich tlie present 

 century furnishes, will occur on May 

 18, 1001. The maximum duration of 

 totality, which will be about six and 

 a half minutes, is rarely surpassed. 

 This will give exceptional opportunity, 

 provided the sky is clear, for work of 

 any kind, photographic or visual. The 

 region of totality is, liowever, incon- 

 veniently remote, and the weather con- 

 ditions, which usually prevail at the 

 stations which will be occupied, are not 

 of the best. The shadow begins off the 

 east coast of Africa, a short distance to 

 the southwest of Madagascar, sweeps 

 northeasterly over the Indian Ocean, 

 and crosses Central Sumatra, Southern 

 Borneo and New Guinea, and a few 

 smaller islands. To visit the track of 

 the eclipse from New York, therefore, 

 one must journey half way around the 

 earth, and it matters little, so far as 

 distance is concerned, whether one 

 starts east or west. In spite of the dis- 

 tance, observations will be undertaken 

 by a number of American and European 

 astronomers. In this country, the 

 Yerkes, Lick, Columbia, Amherst and 

 Naval Observatories and the Massachu- 

 setts Institute of Technology will be 

 represented by skilled observers. Un- 

 der the auspices of the Pioyal and Royal 

 Astronomical Societies, English observ- 

 ers will be stationed at Mauiitius, and 

 Padang, on the west coast of Sumatra. 

 At Padang the eclipsed sun will be only 

 21° from the zenith, and the duration 

 of totality about six and a half minutes. 

 At Mauritius, the chances for a clear 

 feky are much greater than at any other 

 station, but the duration of the total 

 phase is only three and a half minutes. 

 On this account, nearly all the Amer- 

 ican and European observers are plan- 

 ning to visit Sumatra. The observations 

 may have an added value from the 

 fact that the eclipse occurs near the 

 time of minimum sun-spot activity. 



The chief part of the work in this, 

 as in other recent eclipses, will doubt- 

 less be photographic. Owing to the 

 enormous advantages which photo- 



