December 1G, 1910] 



SCIENCE 



877 



comparable than those of an ordinary actinoraeter 

 and the sun. The experiment has been performed 

 in a preliminary way by Professor J. M. Schae- 

 berle, using a silver-on-glass concave mirror of his 

 own construction, as described by him in Science 

 for December 20, 1907. Professor Schaeberle has 

 communicated to the author details of the opera- 

 tion, which gives the following result: using Ste- 

 fan's formula for total radiation of a black body 

 with Kurlbaum's constant, the temperature of a 

 "black" sun is 6563° C. Abs., and the solar con- 

 stant = 3.05 calories. 



On the Need of Adjustment of the Data of Terres- 

 trial Meteorology and of Solar Radiation, and 

 on the Best Value of the Solar Constant: 

 Frank W. Very. 



In this paper Professor Very first points out 

 that owing to the complexity of the field of ter- 

 restrial meteorology and the uncertainty of some 

 of its data, compromise and adjustment are neces- 

 sary if we are to have a consistent theory. The 

 great importance of the solar constant and the 

 Impossibility of observing it directly, demand 

 unusual care ; attention must be paid to the prin- 

 ciple that the adopted value must not violate 

 other facts of observation that rest on a firmer 

 basis than the constant itself. The paper goes on 

 to criticize certain phases of the work of Abbot 

 and Fowle in volume II. of the Annals of the 

 Astrophysieal Observatory of the Smithsonian In- 

 stitution, more especially their virtual assumption 

 that the transmission of telluric radiation by our 

 atmosphere varies in proportion to an experi- 

 mental coefficient raised to a certain power de- 

 pending upon the mass of aqueous vapor in the 

 transmitting column. As a consequence of this 

 and some other points of hardly less importance, 

 Professor Very believes that the value of the 

 solar constant deduced by the Smithsonian ob- 

 servers is much too small and that the true value 

 exceeds three calories; and further that this 

 higher value of the constant reconciles meteor- 

 ological and astrophysieal data which would 

 otherwise be incompatible. It is not possible 

 within the narrow limits here allowable to sum- 

 marize adequately this important paper, which it 

 is hoped will soon be published in full. 



The Lick Observatory Photographs of Halley's 

 Comet: H. D. CuBTis. (Read by Professor 

 Comstock. ) 



In the interval between September 12, 1909, 

 and July 7, 1910, 370 photographs were secured 

 on 95 nights; 206 of these were taken with the 



Grossley reflector, 120 with either a 5J-ineh or a 

 6-inch portrait lens, and 44 with short-focus 

 camera lenses. These auxiliary cameras were all 

 mounted on the tube of the reflector and the 

 guiding was accomplished by means of a 3.5-inch 

 finder of 211.5 inches focal length. The Grossley 

 plates are of great interest in the amount of 

 material they furnish for the study of the envel- 

 opes and other features in the head, which varied 

 greatly from night to night. Photographs taken 

 with the smaller cameras are chiefly useful in a 

 study of the tail, which was photographed up to 

 28° from the head. 



The Society's Expedition to Hawaii for Photo- 

 graphing Halley's Comet : Ferdinand Et.t.fb- 

 MAN. (Read by Professor Comstock.) 

 After a short reconnaissance Mr. Ellerman 

 selected a site on the south slope of Diamond Head, 

 five miles southeast of Honolulu. The first photo- 

 graph was secured on April 14, 1910, and the last 

 on June 11. In all 58 negatives were secured with 

 the 6-inch Brashear doublet and 11 with a 2J-inch 

 Tessar, on 36 difTerent dates. The paper was 

 illustrated with many slides that brought out very 

 clearly the interesting changes in the comet's 

 appearance that occurred toward the end of May 

 and early in June. 



On the Motion of the Particles in the Tail of 

 Halley's Comet on June 6, 1910: E. E. Bar- 

 nard. (Read by Mr. Parkhurst.) 

 The photographs on this date show a discarded 

 tail drifting away from the comet. The rear end 

 of this receding tail was measured with respect 

 to the head on three photographs taken respect- 

 ively at Williams Bay, Honolulu, and Beirut, 

 SjTia. The last two were luade by Mr. Ellerman 

 and Mr. Joy. The Greenwich mean times of these 

 photographs are June 6'' 15" 49"", 20" 4"" and 30' 

 SB". 



Williams Bay minus Honolulu, motion per sec- 

 ond from head, 23.0 miles. 



Williams Bay minus Beirut, motion per second 

 from head, 33.5 miles. 



Honolulu minus Beirut, motion per second from 

 head, 37.4 miles. 



The comet's motion awny from the sun was 

 16.6 miles per second. Hence the motions of the 

 mass with respect to the sun were, respectively, 

 39.6, 50.1 and 54.0 miles per second. These show 

 a decided acceleration of the motion of the mass. 

 Some Results loith a Selenium. Photometer: Joel 

 Stebbins. 

 After a considerable amount of experimenting. 



