192 CARNEGIE INSTITUTION OF WASHINGTON. 



Aa„ and N — D. They have been applied in deriving the definitive 

 clock corrections. These clock corrections have been apphed to the 

 clock stars and the observations are now being collected preparatory 

 to forming the definitive places. 



The work of reducing the right ascensions of the 87,000 San Luis 

 observations has continued and is in a forward state. 



The collimations and levels for the Albany observations of 1907-08 

 have been determined and some progress has been made in reducing 

 these observations. 



In the zenith-distance reductions considerable progress has been 

 made. For the current work the error of runs has been determined 

 at short intervals and these, together with the division errors, have 

 been largely applied, the results being drawn off in duplicate for the 

 further application of the various corrections to follow. 



In training new men as microscope readers, it has been found that 

 enough errors are made by experienced readers to call for an examina- 

 tion of the readings of individual microscopes. As handy tables can 

 be formed for this purpose, the actual time consumed counts for little 

 when compared with the added accuracy. The current circle- 

 readings are undergoing the same treatment. 



Readings on circle A have been made for the determination of its 

 eccentricity, to be utilized in the formation of a table for the further 

 examination of the readings on single microscopes. 



A preliminary determination has been made of the latitude of San 

 Luis, from the observations of stars taken above and below pole. In 

 the reductions of the observations the Pulkova refractions were used. 

 The preliminary results indicate a considerable correction, part of 

 which is due to uncorrected telescope flexure. 



The San Luis reflection observations have also been reduced and a 

 preliminary examination of the results made. While these results 

 will not be discussed at present, there is an indicated cosine flexure of 

 about + 0^3. 



The further reduction of the San Luis zenith distances is awaiting 

 the termination of the correction of circle readings. 



ZONE CATALOGUE. 



The zone catalogue for which the majority of observations were 

 taken from 1896 to 1900 will shortly be ready for the printer. This 

 catalogue contains 11,000 stars, principally included in the zone —23° 

 to —37°. During the past year 800 observations taken in 1891-2 

 have been reduced to the system of the 1896-1900 work, and all of 

 the stars catalogued. The checking of the final places was performed 

 by Mr. Roy. Comparisons were made with other catalogues to 

 catch large errors, and while few errors were found, many appreci- 

 able proper-motions were discovered. The checking of the manu- 



