220 



CARNEGIE INSTITUTION OF WASHINGTON. 



observers may be due to personalities in detennining the nadir correc- 

 tion; or possibly the south-north correction should not be equally 

 distributed each side of the zenith for all observers. 



The differences in the tangent term may be largely due to person- 

 aUties in bisection. As the stellar images were often very poor at 

 great zenith distances, this explanation is entirely possible. 



Another peculiarity was noted in the large deviation in the corrected 

 value of the latitude for the extreme southern zone. 



Assuming —33° 17' 45T47 for the true latitude of San Luis, table 4 

 represents the resulting corrections to the Preliminary General 

 Catalogue. 



Table 4. — Indicated Corrections to Preliminary General Catalogue. 



There is an abrupt break near —60°. An examination of the 

 fundamental curves on which the dechnations of the Preliminary 

 General Catalogue are based indicated no trace of the peculiarity 

 noted. Since the publication of the above results, Professor Hough 

 has called attention to a somewhat similar break in the same region 

 when comparing the Cape Fundamental Catalogue (based on observa- 

 tions taken between 1905 and 1911) with the Preliminary General 

 Catalogue. 



SAN LUIS REFRACTION. 



In continuation of liis investigation of the San Luis declinations, 

 Mr. Roy has analyzed the refraction results. Table 5 presents the 

 refraction factors grouped according to observer and time of day. 



Table 5. 



