1912.] Measurement of Absorption Bands. 131 



Table II. — Observations for Obtaining and Checking Calibration Curve. 



Observer G. W. 



Initial observations by which calibration curve was obtained. 



CO. 



Reading. 



CO. 



Eeading. 



per cent. 





per cent. 





75 -8 



56 



10-1 



M- 4 5 



20 5 



- 2 



45 "8 



19 



27 -5 



- 4 



16 



- 5 



75-8 



62 



72 



60 



62 



41 



39 4 



14 



45 



+ 20 



29 



M 7 



20 -5 







68-2 * 



47 



46 



M 20 



28 -5 







19 7 



- 5 



11 



-10 



30 



2 



52 



26 



60 



28 



58-6 



38 and 32 



66 -5 



45 



43 "5 



20 



50 -6 



26 



66 '5 



41 



26 -8 



4 



52 



28 



38 



15 



23 -9 



2 



72 



66 



67 



48 



50 



16 



53 8 



35 



M = mean of 4 or 5 observations. 



Final observations used to check accuracy of calibration curve. 



Actual CO. 



Eeading 

 of spectroscope. 



CO calculated from 

 curve. 



Difference. 



per cent. 

 50 -6 



28 



per cent. 

 53 



per cent. 

 2-4 



32 -4 



+ 7 



31 



-1-4 



75 -8 



66 



76 



+ 0-2 



6-7 



-10 



- 3 



-37 



43 -5 



16 



41 



-2 5 



63 6 



46 



66 



+ 2 -4 



58 -6 



31 



55 -4 



-3 2 



26 -8 



2 



24 3 



-2 "5 



12 



- 6 



10 -5 



-1-5 



Average error —1 '1. 



difference may exist in the curves of different observers, yet the final results 

 obtained by them need not vary greatly from the true value. ; the variations 

 depending largely on the degree of practice of the observer. 



