152 



REPORTS OF INVESTIGATIONS AND PROJECTS. 



and flocculi, is much greater. A more probable explanation would seem to 

 be that it is due to errors arising in the former series of observations, from 

 astigmatism and other defects of the solar image. The values obtained from 

 the present year's series of observations are now being collected and will be 

 published within a short time. 



One of the most important contributions furnished by the investigation of 

 the rotation of the sun is Mr. Adams's discovery that the hydrogen gas pro- 

 ducing the a line of hydrogen moves with a decidedly greater angular veloc- 

 ity than the general reversing layer, and seems to be subject to quite a differ- 

 ent law from that of the ordinary equatorial acceleration. The first indica- 

 tions that a result of this kind was to be expected were furnished by the 

 study of photographs of the spectra of the center and limb of the sun, and as 

 soon as these became evident the investigation was continued with the reg- 

 ular rotation apparatus of the tower telescope. The results obtained from 

 the earlier plates of the series are given in table 2 : 



Table 2. 



The inclusion of a larger number of results will probably indicate a slight 

 decrease in the value of the angular velocity toward the pole of the sun, but 

 the law will evidently be very different from that of the reversing layer. It 

 also seems probable that the value of the angular velocity at the equator will 

 be somewhat reduced when a larger series of observations is available. 



Some recent work on the blue line of calcium at A 4227 indicates that the 

 rate of rotation given by this line dift'ers from that of the general revers- 

 ing layer. A series of photographs obtained especially for the study of this 

 line is now being investigated. 



Absorption and Scattering in the Solar Atmosphere. — Prof. E. F. Nichols, 

 professor of physics in Columbia University and research associate of the 

 Carnegie Institution of Washington, has just completed an important inves- 

 tigation on Mount Wilson. The object of the work is to determine the law 

 of absorption and scattering of light in the solar atmosphere. An image of 

 the sun, formed by the Snow telescope, falls upon a slit. The rays which 



