220 SEE— RESULTS OF RECENT [April 23, 



which these results are estabhshed are of mathematical character, 

 and in accordance with the principles of dynamics. It is shown, 

 for example, that the spirals observed among the nebulas are chance 

 spirals, and not true geometrical figures. And the general theory 

 is established that the nebulae are formed by the falling together 

 of cosmical dust expelled from the stars by the radiation-pressure 

 of their light and by electric forces. When this fine dust is 

 precipitated under the action of cathode rays it forms meteorites,. 

 and the collection of meteorites forms satellites and larger cosmical 

 bodies. 



A nebula is a cloud of cosmical dust with moons and planets 

 intermixed. The falling together of such nebulosity necessarily 

 produces cosmical vortices, and these are the whirlpool nebulae so 

 long observed in the heavens but not heretofore understood. The 

 expulsion of fine dust from the more active stars gives the pri- 

 mordial material for the formation of nebulse ; the condensation 

 of the nebulae in turn forms stars, so that the total process is a 

 cyclical one, involving both the aggregation of matter into stellar 

 centers and its subsequent diffusion to form new nebulse, stars and 

 systems. 



As the second volume of my " Researches on the Evolution of 

 the Stellar Systems " is a work of nearly 750 pages, it will readily 

 be understood that this summary is too brief to give more than a 

 faint outline of the work. Yet as the results are of general interest 

 to a large class of readers, I have thought they might be mentioned 

 in this brief review. 



Our age is a peculiar one, in that with the progress of astronomy 

 vast masses of observational data are accumulated by the persever- 

 ing industry of self-denying men of science; but so long as these 

 data cannot be put together to yield us the long-sought laws of 

 cosmical evolution, the outcome is almost as vain as the weaving 

 of Penelope's web. Natural philosophers believe, however, that 

 the time is now auspicious for a great advance, not merely in the 

 details, but also in the laws and principles of exact astronomical 

 science. One of the ultimate aims of the physical sciences in all 

 ages has been the discovery of the laws of cosmical evolution. 



