282 SCIENTIFIC RECORD FOR 1882. 



weight is allowed to remain on the Ys in the various meridian circles of 

 • the world. The reductions are purely differential, as has been said. The 

 refraction is computed hj Bessel's tables, with the Greenwich modi- 

 fication. 



The probable error of a clock correction derived from one star is 

 ±0^052, and of a single determination of the equator-point ±0".55, or 

 from four stars zt0".28. The resulting p. e. of a single declination is, 

 above-lOo, ±0". G3, and from -10° to — 2(JO, i0".73. 



For comparison with this work we can refer to the Ann Arbor dec- 

 linations of 195 stars, made with a circle of exactly the same size as 

 that of Dublin, and also by the same makers, published by the Wash- 

 l)urn Observatory (1881). 



This catalogue was observed by Mr. Schseberle in 1879, and the p. e. 

 •of a single night in declination is ±0".55; in K. A. i0^040 sec. (J. 

 Schjellerup at Copenhagen (10,000 stars, p. xvi), found between 0° and 

 -fl5o^. e. in Dec. rtO".G9, and between 0° and -15^, ±0'^95. 



The magnitudes of the stars have been assigned on Argelander's 

 ecale, and a note of the color of each star is given for each observation. 



The main object of the work is to bequeath good determinations of 

 position of a large number of red stars, which may serve hereafter to 

 show if the red stars as a class have any peculiarities of proper motion. 



Besides this object, another has been attained, in that 321 red stars 

 Lave been observed for color and magnitude on three or four nights 

 each on the average. 



Dr. Dreyer has now undertaken the observation of a large number ot 

 ■zero stars for Schoenfeld's Durchmusterung with this circle, which, like 

 the large refractor of the observatory, is not destined to be idle. 



Double stars. — No. (3 of "Publications of the Cincinnati Observatory" 

 lias been issued. It contains micrometrical measures of double stars 

 made with the 11-inch refractor in 1879-'80, consisting partly of obser- 

 vations preliminary to the formation of a general catalogue of known 

 double stars situated between the equator and 30° south declination, 

 and partly of observations of objects which Mr. Burnham has found to 

 oeed re-observing. The cases of notable ditferences from previous meas- 

 ures are collected in the introduction. The refractor appears to have 

 been much improved since the object-glass was refigured by Messrs. 

 Alvan Clark & Sons. 



The double star observations of Baron Dembowski are to be pub- 

 lished in the Atti della B. Accademia del N'. Lincei. They will fill three 

 to four of the (quarto) volumes, or about 1,500 pages in all, and are to 

 he edited by Professor Schiaparelli. 



Variable stars. — Prof. E. C. Pickering, of Harvard College Observa- 

 tory, has prepared and published in i)ami)hlet form a plan for securing 

 observations of the variable stars. It is well known to astronomers that 

 fehis obser^'atory is doing systematic work in the study of the variable 



