MOUNT WILSOX SOLAR OBSERVATORY. 



213 



The conditions for observation were in general perhaps somewhat 

 below the normal for IMount Wilson. A record of the seeing, on a 

 scale of 1 to 5 (the latter being perfect) is shown herewith, together 

 with the wind-record from Mr. Hoge's personal observations. 



The observations show 10 per cent 

 high winds, 33 per cent brisk and mod- 

 erate, and 57 per cent light to calm. 



The outer dome-covering of sheet- 

 iron, substituted for the canvas cover- 

 ing formerly used, was completed in 

 the spring of 1913 and has proved 

 effective in keeping down the tempera- 

 ture within the building during the hot weather. The highest tem- 

 perature recorded was 29°. 9 C. on July 11, while the lowest was 

 — 8°.0 C. on January 5. 



Direct Photography. 



In continuation of his photographic work on nebulae and star clus- 

 ters with the 60-inch reflector, Mr. Pease has obtained photographs 

 of the following objects in the principal focus of this instrument: 



Spiral nebulge: N. G. C. 205, 278, 1023, 2403, 2681, 2976, 3593, 4216, 4900, 5383, 



5857-9, 5907, 6217. 

 Spindle nebula: N. G. C. 5308. 



Planetary nebula;: A^ G. C. 1501, 1535, 2022, 2392, 7662. 

 Irregular nebula; : A^ G. C. 650, 1555, 4449. 

 Globular clusters: N. G. C. 6093, 6218. 



Other objects also photographed in the principal focus include 

 Nova Geminorum, the region of Encke's comet, and the regions SU 

 Draconis and SW Draconis. 



The following objects have been photographed with the Casse- 

 grain combination of 100-feet equivalent focal length: 



Planetary nebula^: A'. G. C. 1535, 6095, 7026, 7027. 



Also the star B. D.+30° 3639, found by Campbell's spectroscopic observations to 

 have a hydrogen envelope. 



Miss Van Deusen has counted the stars on photographs of the 

 cluster Messier 13, made^ by Mr. Pease with ex- 

 posures ranging from 6 minutes to 37.5 minutes. 

 Counts were made in two directions at right angles 

 to one another and the results here given are the 

 means of the two. These results are only prelimi- 

 nary and will doubtless be somewhat modified with 

 increased experience in counting. 



Stellar Parallaxes. 



Mr. van Maanen has begun a series of photographs with the 

 60-inch reflector to determine whether satisfactory measurements of 

 stellar parallaxes can be made with the 80-foot-focus Cassegrain com- 

 bination. This work is still in its preliminary stages and none of the 

 plates have yet been completely measured. 



