264 CARNEGIE INSTITUTION OF WASHINGTON. 



1 night, while 21 nights were calm. The poorest observing weather 

 was in December. Table 2 gives a record of the seeing, on a scale of 1 

 to 5, together with the wind record as observed each night: 



The average range of temperature in the dome between opening 

 and closing time was 6° C. The highest temperature recorded was 

 30.6° C. on August 19, while the lowest was —3.5° on February 20. 



DIRECT PHOTOGRAPHY. 



Mr. Ritche}', who resumed photographic observations of nebulae 

 with the 60-inch reflector in Alay, has obtained the following long-expo- 

 sure negatives at the Newtonian focus: 



N. G. C. 69G0, exposure 12 hours. N. G. C. 5457, exposure 9 hours. 



N. G. C. 6946, exposure 9 hoiu-s. N. G. C. 224, exposure 9 hours. 



During the j^ear Mr. Pease has obtained the following photographs 

 at the Newtonian focus of the 60-inch reflector: 



Spiral nebuljB, left hand N. G. C. 1186, 3666, 3938, 5921, 5857-9. 



Spiral nebulae, right hand N. G. C. 5660, 5666, 5669. (These appear on a 



single plate.) 



Gaseous nebulte N. G. C. 6309, 700S. 



A single plate contains N. G. C. 2825, 2826, 2827, 2829, 2830, 2831, 2832, 



2833, 2834, 2839, and 27 others. 



Of the last group, 6 are spindle nebulae with nucleus, 3 elongated 

 with no nucleus, and 28 are nebulous spots or stars; the field is about 

 36 minutes of arc on a side. 



DIRECT DETERMINATION OF PARALLAXES. 



During the past year 440 plates have been taken by Mr. van Maanen 

 with the 80-foot focus combination of the 60-inch reflector ; on many of 

 the plates there were 2 exposures, making a total of 603 exposures, of 

 which 427 were for the determination of parallaxes. 



For 17 stars, each with from 10 to 18 exposures, the measures and 

 reductions have been finished. The mean probable error of a parallax 

 is 0''0055. Although present indications point to the absence of large 

 systematic errors, this question can not be fully discussed until more 

 material is available. 



During the middle of the night, when the parallax factors for stars 

 near the meridian become very small, the instrument has been used 

 for photographing stars with large proper motions (>0':'50 a year), the 

 purpose being to detect possible companions. First-epoch plates have 

 been secured for 66 stars, with exposures of 15 minutes, which show 

 stars to approximately the fourteenth magnitude. After an interval 

 of one or two years it should be possible to detect stars of common 

 proper motion. 



As the pubUshed Usts of stars of large proper motion were far from 

 complete, Mr. van Maanen has collected the data from all sources 

 published as late as 1914. 



