SMITHSONIAN MISCEIJ-ANEOUS COLLECTIONS 



VOL 



Calling c the corresponding energy at the selected place in the sun's 

 spectrum, it may be assumed that approximately the amount of 

 energy absorbed from the sun's rays by ozone is 



{— .e) summed for spectrum places 22, 24, and 26. 



The accuracy of these measurements, depending, at the greatest, on 

 differences of the order of (0.890—0.860), cannot exceed i part in 30, 

 assuming no accidental errors. Further, the measurements extend 

 over times of from one to three hours. It is presumptuous to assume 

 always a negligible change in the amount of ozone during such 

 considerable times. Any change in the general transparency of the 

 sky is probably negligible, since it would alfect both the numerator and 

 the denominator of the above expression. It takes only 30 seconds 

 for the run through the part of the spectrum used, so that the time 

 is short to produce differential errors within this band. 



Because the results presently to be given differ so considerably in 

 magnitude and range from the values of Dr. Dobson and those asso- 

 ciated with him, it has been thought advisable to devote considerable 

 time and study to the indications of the Chappuis band. 



Is the discrepancy due to the presence of other atmospheric lines 

 within the Chappuis ozone band? A count of the number of atmos- 

 pheric lines, designated as such in St. John's recent revision of 

 Rowland's Solar Spectrum Table, ^ leads to the following table : 



Spectrum 

 range 



Wave-length 

 range 



Number of lines 



HoO 



In figure 4 the area of that part of the ozone band under trial 

 corresponding to the region of the first three lines of the above table 

 is plotted against the corresponding precipitable water vapor in the 

 atmosphere ; in figure 5, is similarly plotted that corresponding to the 

 lower line. No connection with water vapor can be certainly inferred 

 from these two plots. What little dependence there seems to be is in 

 the wrong direction ; that is, the greater the water vapor, the smaller, 

 on the average, seems to be the area of the band. This apparently 

 inverse effect probably results because the season of greatest water 



' Carnegie Institution Pulilicatinns, 306, 1928. 



