SOLAR OBSEIRVATORY. 169 



(11) The sudden increase in angular velocity at latitude 75° may perhaps 

 be a genuine effect similar to that found among the lines of the reversing layer 

 which gives systematic deviations. 



(12) The large rotational values given by A 4227 and Ha, and the differ- 

 ences found for Ha at the limb and inside the limb, may be accounted for on 

 the basis of differences of level in the solar atmosphere. 



Radial Motion of the Calcium Vapor in the Solar Atmosphere. 



An extensive study of the motion of the calcium vapor in the flocculi has 

 been made by Dr. St. John. The instrument used for this purpose is the 18- 

 foot spectrograph of the Snow telescope, provided with an attachment by 

 which successive images of the H or K line, corresponding to adjoining 

 regions of the solar image, can be photographed in the third spectrum of an 

 8-inch Michelson grating. The positions of the H, and K, and the H3 and 

 Kg lines have been measured on a large number of plates and the results are 

 now being reduced for publication. 



Areas and Distribution oe Prominences. 



Dr. Abetti has made an extended investigation of the areas and the distri- 

 bution in latitude of the prominences shown by the series of plates taken 

 daily with the 5-foot spectroheliograph and Snow telescope. Although the 

 observations included in the discussion cover several hundred days, the inter- 

 val is of course too short to give any reliable information as to periodic 

 variations in the areas or distribution of the prominences. There is evidence, 

 however, for believing that the calcium (H) prominences are on the average 

 higher than those shown by the hydrogen (Ha) rays. 



Spectrum of the Zodiacal Light. 



Dr. Fath has continued his observations on the spectrum of the zodiacal 

 light, which were begun at the Lick Observatory. A cumulative exposure of 

 j2h 21™ with the spectroheliograph used at Mount Hamilton, and kindly 

 loaned by Professor Campbell for a continuation of the observations, gave 

 a spectrum which resembles the solar spectrum exactly in so far as can be 

 judged from so small an object. Two lines are shown with certainty. These 

 have been identified with G and a blend of the H and K lines of the solar 

 spectrum. A comparison sky spectrum secured under the same conditions 

 shows only these lines within the limits of spectrum obtained on the zodiacal 

 light plate. There is no indication of bright lines on the zodiacal light spec- 

 trogram. The evidence therefore indicates strongly that the zodiacal light is 

 reflected sunlight. 



THB SIXTY-INCH RSFI,e;CTOR. 



The 60-inch reflector was completed and first used for visual and photo- 

 graphic observations in December, 1908. It was apparent from the outset 



