726 



SCIENCE. 



[N. S. Vol. III. No. 72. 



tained for calculating, if possible, a more ex- 

 act formula. No adequate theoretical ex- 

 planation has been found, as yet, of the ob- 

 served variations, though it is suspected that 

 the annual part of the variation is diie to me- 

 teorological causes, and that the other part 

 may be caused by changes in the relative 

 positions of portions of the earth's mass, 

 such as movements of great masses of 

 water and depositions of ice and snow. 



A number of important problems are in- 

 volved in this question of latitude varia- 

 tion. All the determinations of astronomy 

 have been made on the assumption that our 

 latitudes do not change. When the as- 

 tronomer is supplied with sufficiently exact 

 data the determination of various constants 

 used in astronomy must be recalculated. 

 Dr. Chandler and others have already be- 

 gun the reinvestigation. 



The problems so far discussed belong 

 to pure astronomy. In the past forty 

 years there has grown up, with a vigorous 

 growth, a new branch of astronomy styled 

 by some The New Astronomy. This branch 

 deals with the beautiful and interesting in- 

 vestigations of the heavenly bodies made by 

 the aid of that wonderful instru.ment of 

 modern research, the spectroscope. On 

 this occasion I will not trespass on your 

 patience by attempting to describe to you 

 the achievements of the new astronomy in 

 the examination of the sun and the planets, 

 the stars, nebuliB and comets. By the in- 

 vestigations of this young science of spec- 

 troscopy applied to the heavenly bodies, we 

 get our first and accurate ideas of their 

 constitution. On the spectroscopist we must 

 depend for our knowledge of the surround- 

 ings of the sun and planets — the materials 

 entering into the make-up of the stars, 

 comets and nebulse. The study of the 

 stellar spectra brings wonderful informa- 

 tion in regard to variable stars and the 

 motions of stars. 



The discoveries of argon and helium have 



unlocked some doors to knowledge previ- 

 ously closed tightly. On astrophysics the 

 astronomer of the 20th century must de- 

 pend for solving many problems. It is 

 likely that a study of planetary spectra 

 will give us the means of determining the 

 rotation times of the planets— Venus and 

 Mercury. 



We have thus briefly and inadequately 

 mentioned some of the problems which the 

 astronomer of the next century must deal 

 with. When we consider the progress made 

 during the past twentj'-years only, we are 

 led to believe that world-wide cooperation 

 in astronomical work will be one of the 

 great features of the coming century. Only 

 by such cooperation, directed by the ablest 

 astronomers, can the most effective work be 

 done. With such cooperation many of the 

 troublesome problems will undoubtedly be 

 solved. J. K. Rees. 



A NEW FORM OF RADIATION* 



As my investigations will have to be 

 interrupted for several weeks, I propose in 

 the following paper to communicate a few 

 new results. 



§ 18. At the time of my first communica- 

 tion it was known to me that X-rays were able 

 to discharge electrified bodies, and I sus- 

 pected that it was X-rays, not the unaltered 

 cathode rays, which got through his alumi- 

 num window, that Lenard had to do with in 

 connection with distant electrified bodies. 

 When I published my researches, however, 

 I decided to wait until I could communicate 

 unexceptionable results. Such are only ob- 

 tainable when one makes the observation in 

 a space which is not only completely pro- 

 tected against the electrostatic influences 

 of the vacuum tube, leading-in wires, in- 

 duction coil, etc., but which is also pro- 

 tected against the air coming from the 



* Second communication to the WuTzburg Ph3'sico- 

 Mediciil Society. Reprinted from the translation in 

 EJeciricity. 



