L)ki:vi-;ij — . / Sin-rrf/ o1 the Spiral Nchu la 3Icssirr S3. 13 



As the values of ^ and 7/ did not agree as well as i liad lio[)ed, I 

 made a number of trials with different values of A and i>, but was 

 unable to obtain any better results. The somewhat heterogeneous 

 material of meridian observations available, as well as the fact 

 ascertained elsewhere,^ that positions of stars of magnitudes 7 to 10 

 on long exposure plates taken with a reflector can only be measured 

 with a probable error of about 0"-6 in both coordinates, is amply 

 sufficient to account for the differences found. Adopting the mean of 

 the above values, viz. P = - 0-000252, Q = - 0-002594, ^ =^ - 107"-14, 

 = + 7"-23, and computing with these the standard coordinates of 

 the four stars, and from them the apparent right ascensions and 

 declinations, the following differences are found (Meridian minus 

 Photograph) : — 



(1) -0-06 +0".40 



(2) +0-04 -0-62 



(3) +0-05 +0-18 



(4) -0-05 +0-35 



In addition to these stars, there are five others on the plate, which 

 have been observed on the meridian ; but they are, with one exception, 

 below the ninth magnitude, and are not well situated (four of them 

 being close together), so that they are not suitable for the determination 

 of the constants of the plate. I have, however, thought it would be 

 of interest to compare the meridian observations with the photographic 

 measures. The following star-places for 1 899-0 were available, the 

 zone results being again corrected by Auwers' table, and Eonn VJ. 

 being reduced to the same equinox as the others by Oertel's table in 

 A. N. 2895. 



+ 30°-238 Mag. 9-5 : 



Cambridge, 1*' 26- 28-81 (2) + 30° 13' 57"-9 (2) 

 Dunsink, 28 -96 (4) 52 -8 (4) 



Adopted, 1 26 28-96 + 30 13 52-80 + 5^00 + 33"-19. 



+ 30°-241 Mag. 9-5 : 



Dunsink, 1" 28°^ 57^53 (4) + 30° 19'36"-1 (4) -f 5^03 + 33"-04. 



^ H. C. Pluiiiiiu'r, Moiitlily Notices, vol. Ixiii., \). 25. 



