212 CARNEGIE INSTITUTION OF WASHINGTON. 



REDUCTION OF OBSERVATIONS. 



The reduction of the San Luis zenith-distance observations, under 

 the supervision of Mr. Roy, is now practically completed. The pre- 

 cessions in both right-ascension and declination are computed and 

 checked and the declinations are reduced to the mean epoch 1910.0. 

 Means of the observations in declination are being formed and a 

 further scrutiny of discordant results is being made. The secular 

 variations also have been largely duplicated. 



With the near completion of the San Luis zenith-distance reductions, 

 Mr. Roy has been able to make greater progress in the reduction of the 

 Albany zenith distances. The first discussion undertaken was of the 

 observations made by each observer of stars, both above and below 

 pole, to ascertain a system representing the Albany instrument and 

 observers. The first results obtained, the latitude and the correction 

 to the Pulkova refractions, are as follows: 



A. J. Roy +42° 39' 12r78 -OTOSG tan Z. D. 



W. B. Varnum +42° 39' 12':85 -0':i74 tan Z. D. 



It is to be noted that after Mr. Varnum has obtained definitive 

 results for the effect of irregular refraction upon the observations, 

 it will become necessary to rediscuss the observations in order that this 

 term may be introduced in the final results. The promised gain in the 

 harmonizing of the observations fully justifies this step being taken. 



MISCELLANEOUS INVESTIGATIONS. 



Mr. Wilson continued his work on the selection of standard stars 

 for a photographic survey until April 1921, when the project was 

 postponed. The material gathered will be furnished to anyone de- 

 siring to use it. 



Mr. Wilson also investigated the relation between period and eccen- 

 tricity in binary systems. Treating 235 systems, he found an apparent 

 rapid increase in eccentricity depending upon the period in systems 

 with a period less than 100 days, followed by a minimum for the 

 systems with a period of from 100 days to 50 years. When the material 

 was divided into giant and dwarf classifications, the relatively rapid 

 increase in eccentricity in the shorter-period binaries seemed to be 

 largely due to the predominance of giant systems in these groups. 

 An increase in the number of dwarf systems would tend to flatten the 

 curve. The minimum referred to is partially due to the systematically 

 low eccentricities of the dwarf stars in these groups and partially to the 

 greater probability of the discovery of the less eccentric orbits among 

 the long-period spectroscopic binaries. As more spectroscopic binaries 

 with long periods are added it is probable that most of the discordances 

 from a uniform mean period-eccentricity curve will be removed. 



