5 68 THE POPULAR SCIENCE MONTHLY. 



would reveal more than Huyghens was able to detect with his un- 

 wieldy instrument. 



Dominic Cassini soon after discovered a fourth star near the three 

 seen by Huyghens. The four form the celebrated trapezium, an object 

 interesting to the possessors of moderately good telescopes, and which 

 has also been a subject of close investigation by professed astronomers. 

 Besides the four stars seen by Cassini, there have been found five 

 minute stars within and around the trapezium. These tiny objects 

 seem to shine with variable brilliancy ; for sometimes one will surpass 

 the rest, while at others it will be almost invisible. 



After Cassini's discovery, pictures were made of the great nebula 

 by Picard, Le Gentil, and Messier. These present no features of spe- 

 cial interest. It is as we approach the present time, and find the great 

 nebula the centre of quite a little warfare among astronomers now 

 claimed as an ally by one party, now by their opponents that we 

 begin to attach an almost romantic interest to the investigation of 

 this remarkable object. 



In the year 1811, Sir W. Herschel announced that he had (as he 

 supposed) detected changes in the Orion nebula. The announcement 

 appeared in connection witli a very remarkable theory respecting 

 nebuloe generally Herschel's celebrated hypothesis of the conversion 

 of some nebulas into stars. The astronomical world now heard for 

 the first time of that self-luminous nebulous matter, distributed in a 

 highly-attenuated form throughout the celestial regions, which Herschel 

 looked upon as the material from which the stars have been origi- 

 nally formed. There is an allusion to this theory in those words of the 

 Princess Ida : 



"There sinks the nebulous star we call the Sun, 

 If that hypothesis of theirs he sound." 



And in the teaching of " comely Psyche : " 



" This world was once a fluid haze of light, 

 Till toward the centre set the starry tides, 

 And eddied into suns that, wheeling, cast 

 The planets." 



Few theories have met with a stranger fate. Received respectfully at 

 first on the authority of the great astronomer who propounded it 

 then in the zenith of his fame the theory gradually found a place in 

 nearly all astronomical works. But, in the words of a distinguished 

 living astronomer, " The bold hypothesis did not receive that confir- 

 mation from the labors of subsequent inquirers which is so remarkable 

 in the case of many of Herschel's other speculations." It came to 

 pass at length that the theory was looked upon by nearly all English 

 astronomers as wholly untenable. In Germany it was never aban- 

 doned, however, and a great modern discovery has suddenly brought 

 it into general favor, and has in this, as in so many other instances, 



