1895.] on the Radiant Heat from the Moon. 637 



Moon's primary image. The concentration of heat will be reduced 

 some sixty times, but it will be at the same time possible to screen off 

 extraneous disturbances of the needle better. 



I think that the comparison of the heat through glass with the 

 total heat is of sufficient importance for repetition with greater care, 

 and that of the Sun's heat with the Moon's heat should be gone over 

 again, as also that of the Sun's light with the Moon's light, when we 

 find so large disagreements between the various figures hitherto 

 published. We have — 



Lambert 400,000 to 1 



Bonguer 300,000 „ 



Wollaston 800,000 „ 



Bond 480,000 „ 



Zollner 618,000 „ 



W.H.Pickering 350,000 „ 



Sir William Thomson 70,000 „ * 



Again, one would like to see Langley's experiments on the solar and 

 lunar heat spectrum repeated. 



We want, however, more workers. If preparations for heat 

 observations during eclipses were made' at several stations, widely 

 apart, and as much as possible in less cloudy climates, over the 

 surface of the earth, we should in a comparatively short time clear up 

 doubtful points to an extent for which a lifetime of our work would 

 be inadequate, and if this lecture should conduce to this end I shall 

 feel, if for no other reason, that my trouble will have been fully 

 rewarded. 



* This last value was probably much affected by the smoky atmosphere of 

 Glasgow. 



