OP ARTS AND SCIENCES. 401 



planets to pass easily through it, but at the same time enough of a 

 solid to admit of transverse vibrations. Stokes suggests water with a 

 litile glue dissolved in it as a coarse representation of what is required 

 of the ether. 



Mr. G. A. Hirn has written recently on the constitution of celestial 

 space. He decides against the existence of an all-pervading medium. 

 He thinks that matter exists in space only in the condition of distinct 

 bodies, such as stars, planets, satellites, and meteorites. In nebulae it 

 is in a state of extreme diffusion ; but elsewhere space is empty. But 

 how would it be after the correction is applied for the equation of 

 light ? Humboldt said that the light of distant stars reaches us as a 

 voice from the past. The astronomer is not seeing for the most part 

 contemporaneous events. He is reading history ; and often ancient 

 history, and of very different dates. Stellar photography reveals mil- 

 lions of stars which cannot be seen in the largest telescopes, and new 

 harvests of these blossoms of heaven (as they have been called) spring 

 up like the grass in the night. Numbers fail to express their probable 

 distances and the time taken by their light in coming to the earth. 

 In the theogony of Hesiod, the brazen anvil took only nine days in 

 falling from heaven to earth. On the other hand, the reduction of 

 the sun's distance by three per cent not only affects its mass and 

 heat, but it changes the unit of measure for the universe. Such are 

 the remote results of any change in the estimated velocity of light. 



We may thank Professor Michelson not only for what he has estab- 

 lished, but also for what he has unsettled. In his various researches, 

 which I have hastily sketched, but which require diagrams or models 

 to be clearly understood, he has displayed high intelligence, great 

 experimental skill and ingenuity, and unflagging perseverance. With 

 a high appreciation of his work, the Rumford Committee recommends 1, 

 and the Academy voted, that the Rumford Premium be awarded to 

 him. 



vol. xxiv. (n. s. xvi.) 26 



