STC DV OF THE VARIABLE STARS 



179 



Altogether Miss Leaviti has added 1,500 new variables to the already 

 rapidly growing list. 



It may be asked, why it is necessary, or even desirable, to go on 

 indefinitely with the discovery of new variables. The answer is that, 

 aside from the value of adding any new fact about the universe to the 

 sum of human knowledge, the problem is now so well advanced that it 

 seems unwise not to render the search complete for the whole sky. 

 A serious international attempt is about to be made, for the first time, 

 to investigate systematically all the leading problems concerned in 

 the construction of the universe, so that a scientific cosmogony may be 

 possible. It will be of value in this greatest of all problems to find 



100. 



too 



300. 



3-Ul.I.O Cvtv.ti una-. TV^oA. 331. t. 



* Tjyu.o -& 2& 1 8^ ATI w q "3 .(Mlfo«o\»M,) 



3i* 3. CJUeJtjOLVoAioWl 0$ C UCWvu- Mo. 130. ^.CJWsfalVaxA- ^«M^ * No. M,. 

 Velocity curves and Light-curves of Variable Stars. (The light-curves are inverted.) 



the discussion of the variable stars reasonably complete for the whole 

 sky. At the Harvard Observatory, where variable stars have been 

 given serious attention during more than twenty years, a new cata- 

 logue, compiled by Miss Cannon, is in course of publication, which 

 contains reference to about 1,850 variables. This does not include the 

 variable stars in the Magellanic Clouds. Also, a committee of the 

 Astronomische -GeseUschaft. consisting of the well-known astrono- 

 mers, Duner, Midler, Oudermans and Hartwig, have in hand the 

 preparation of a catalogue, which will be an extension of the former 

 catalogues of Chandler. 



The work of discovery, however arduous, is but a small part of the 

 whole problem of the variable stars. Long series of observations are 

 necessary, in order to learn the amount, duration and rapidity of the 

 light-changes, or, in other words, to determine the light-curve. 



