OF ARTS AND SCIENCES. 



891 



on June 23, 1880. The first observations which can be reduced are 

 those made by M. Ghisenapp* on July 3, 1880. lie adopted a series of 

 comparison stars, which will probably be employed by other observers 

 of this variable. Table XII. gives their Durchmusterung designa- 

 tions, and their right ascension, declination, and magnitudes taken from 

 that catalogue. The next columns give the designation by Glasenapp, 

 and the assumed light in grades. Measures of these stai's were made 

 on three evenings at the Harvard College Observatory with Photom- 

 eter I.f attached to a telescope of four inches aperture. These measures 

 must be regarded as provisional ; a much more precise determination 

 of their light will probably be obtained next year with a large merid- 

 ian photometer. From these measures, which are given in the seventh 

 column, the grades of M. Glasenapp are reduced to magnitudes by the 

 formula, m = 9.5 — 0.07 g, in which g denotes the number of grades 

 and m the corresponding magnitude. The results are given in the 

 eighth column. The last two columns give the residuals found by 

 subtracting the H. C. measures from the magnitudes of M. Glasenapp 

 and of the Durchmusterung. 



TABLE XII. — Comparison Stars for DM. 81°25. 



The star DM. 81^18 is either variable, or its light in grades is 

 erroneously given by M. Glasenapp. An examination on different 

 evenings showed that it was decidedly brighter than 8I°30. This is 

 confirmed by the measures and by the Durchmusterung magnitudes. 

 If the light in grades was written 17.6 by mistake for 27.6, the mag- 

 nitude becomes 7.6 instead of 8.3, and the residual -\- 0.1 instead of 

 -{- 0.8. This cannot be a typographical error, since the stars were 

 arranged by M. Glasenapp in the order of brightness, and 81°18 is 



* Astron. Nach., xcviii. 61. 

 t Annals, xi. p. 7, figs. 5 and 6. 



