OP ARTS AND SCIENCES. 



145 



The dates upon which this has been determined, together with the 

 principal quantities entering into the computation, are here given in 

 tabular form. 



Table of Tr.^nsbiission Coefficients. 



The mean of the values of t is 0.9852, and t 7.6, the amount of 

 lunar radiation transmitted by the entire atmosphere at the ordinary 

 pressure, is 0.8925. 



SUiMMART. 



I. We have shown how an instrument may be constructed, capable 

 of measuring very minute radiations. 



II. We have measured the radiations of several rocks at near 100°, 

 and presented the results in a table. 



III. We have found that the heat which our planet receives from 

 the moon is to that from the sun as 1 to 184,560. 



IV. We have compared the lunar rays with solar rays reflected 

 from rocks, with reference to the absorption of each by quartz. 



Y. We have constructed a curve, representing the change of trans- 

 mission of lunar rays by our atmosphere with changes in altitude of 

 the moon. 



VI. We have found that our atmosphere, at the ordinary pressure, 

 transmits 89.25% of the vertical lunar beam. 



VOL. XXIV. (S. S. XVI.) 



10 



