SCIENCE-GOSSIP. 



339 



HAS THE MOON AN ATMOSPHERE? 

 By Frank C. Dennett. 



\ T first, the question whether the moon has an 



atmosphere appears very easy to answer, 



yet it is one which cannot be replied to off-hand, 



and would be met by different authorities with 



absolutely contradictory replies. 



Dr. Johnston Stoney and those who think with 

 him will tell us that the atmosphere of any celes- 

 tial body must depend upon its mass, and the 

 pulling power or gravitation exerted thereby. The 



five-prism direct-vision spectroscope, could none 

 of them observe any widening of the lines of the 

 spectrum, such as might be expected from the pre- 

 sence of an atmosphere. An observation by Mr. 

 (now Sir) William Huggins of the occnltation of 

 the spectrum of e Piscium, brought to the notice 

 of the Royal Astronomical Society in January, 1865, 

 appeared also to strengthen the view that there 

 could be no appreciable atmosphere to our satellite. 



, rm ' ! ■ ' ' I 



molecular •. ■ ':vcn the slowest of the com- 



ponent phere, carbon di 



amount-. 10 vC mile-, per M.-cond at C. The 

 man of the moon thai ol the earth being 



ould only exert siilluient gravitational 

 power to hold a gas having miles, 



or levi, per second 



n out |jy many ob .< r ■. ation I 



which I made. For h tarn 1 . al 1 1 e 



with a 

 . :uid in that 



1. J. Stone, ••■nil two dense (lint 

 nd Mr. A. C. Ranyard, with a 



The observations of stellar occultations seem to 



.neially tin: impression thai there is no 

 refractive phenomena such as might be expected. 

 Perhaps one of the most interesting of these 



that made photographically at 



Harvard by Mr. Edward S. King, when on the 61 



magnitude star 20 Arielis was 01 1 tilted on Febt uai \ 



, I, bul no trace of any dimming ol the si.-u 



,;,■,, could be discovered, notwithstanding that the 



I employ d Beamed to favour the discovei y 



. .1 Hm slight! 1 obsi in Ing medium 



(in the olhei hand, nearly all observers who 



have made the moon an object ol persistent study 



seem to roine to the 1 lusi hat there is an 



othet ' e Hi. phenomena obsei tred 



