ASTRONOMY — UAht. 79 



LATITUDE AND LONGITUDE OF THE SOLAR OBSERVATORY. 



The results obtained by Messrs. Smith and McGrath, of the Coast 

 Survey, for the astronomical latitude and longitude of the Solar Observa- 

 tory, may be found in Contribution No. 9. They may be briefly sum- 

 marized as follows : 



The latitude observations, v.hich were made on three nights, gave a 

 weighted mean value of 34° 12' 55.07''' + 0.06". The reduction to sea 

 level, to take account of the curvature to the vertical, is 0.28", giving 

 34° 12' 54.79''' as the reduced latitude of the point of observation. 



The difference of longitude between Los Angeles and Mount Wilson 

 was determined, with the aid of the new transit micrometer, on six nights. 

 The mean difference is -|- o™ 47.571^ + o.oo8^ From the known longi- 

 tude of the transit at Los Angeles, determined from the observations of 

 1892, the longitude of the transit at Mount Wilson comes out 7^^ 52"" 

 14.130^^=118° 3' 31.95". ^Ir. Smith determined by local triangulation 

 the position of the Snow telescope pier, with reference to his observing 

 station, and thus obtained the following results : 



Mount Wilson triangulation station : o t n 



Latitude 34 12 59-72 



Longitude 1 18 3 45-54 



Snow telescope pier : 



Latiti'.de 34 12 59.53 



Longitude 118 3 34-89 



These vahies, as compared with the geodetic position of the Mount 

 Wilson triangulation station on the United States standard datum, show 

 that the astronomical latitude is 26.50" less than the geodetic, and the 

 astronomical longitude is 5.63" greater than the geodetic. The deflection 

 in the meridian is thus one of the largest yet observed in the United 

 States. 



SMITHSONIAN EXPEDITION. 



The large number of determinations of the solar constant made by the 

 Smithsonian Expedition during the summers of 1905 and 1906 should 

 be sufficient to settle beyond any doubt the important question whether 

 this quantity is actually a constant, or undergoes such variations as the 

 previous work in Washington led Secretary Langley and Mr. Abbot to 

 suspect. The summer weather in Washington is usually unfavorable 

 for work of this kind, but the spring and autumn furnish a greater num- 

 ber of opportunities for simultaneous observations. The very close agree- 

 ment of the measures made on the same date at the two stations indicates 

 that the method of correcting for absorption in the earth's atmosphere is 

 thoroughly sound. I heartily agree with Mr. Abbot's view that the most 



