304 



Mr. S. P. Langley on the Amount 

 Table II. 



I. 



II. 



III. 



IV. 



V. 



Original 



Observed 



Observed 



Observed 



Observed 



intensity 



intensity 



intensity 



intensity 



intensity 



(ordinarily 



after one 



after two 



after three 



after four 



unknown). 



absorption. 



absorptions. 



absorptions. 



absorptions. 



A, B, C, &c. 



La, Bb, Cc, &c, 



A« 2 ,B6 2 ,Cc 2 ,&c. 



Aa 3 , Bb\ Cc 3 , &c. 



A« 4 , B6 4 , Cc 4 , &c. 





•01 



•0001 



•ooo 



•0000 





•1 



•01 



•00 1 



•0001 





•2 



•04 



•008 



•0016 





•6 



•36 



•216 



•1296 





•7 



•49 



•343 



•2301 





•7 



•49 



•343 



•2301 





•8 



•64 



•512 



•4096 





•9 



•81 



•729 



•6561 





•9 



•81 



•7^9 



•6561 





1-0 



1-00 



1-000 



1-0000 



10= 



5-9= 



465= 



3-881 = 



33143 = 



A+B+&C. 



Aa+B&+&c. 



Aa 2 +B6 2 +&c. 



Aa 3 +B6 3 +&c. 



Aa 4 4-B& 4 4-&c. 



=X 



=M 



= N 



= 



=P 



If we determine the coefficients of transmission from a 



N 

 comparison of II. and III., we have ^ = -789 ; if from II. and 



IV., we have (^) 2 = '812; if from II. and Y., we have 



(PV 

 — J 3 = -825 ; and the corresponding mean absorptions are 



-QWl75. 



1 -S= ' 21 ' i-Q*=°- 188 » 



So that all our observations at different altitudes are in sub- 

 stantial agreement in indicating an absorption of from 18 to 

 21 per cent., while yet all our inferences from them are quite 

 wrong. 



If we observed by some method which discriminated 

 between the different radiations of which the heat or light is 

 composed, we should have, from the observations in columns 

 II. and III., 



(Aay , (my (Cc)\-....(jjy 



Bb 2 



A + B + C + ....J 

 •01 



+ 



+ 



Uc a 



J/ 



1 + -01 + -04^ &C> 



= 10 



(the true value) ; while the ordinary and erroneous method, 

 which docs not discriminate, gives 



