306 PROCEKDINOS OF THE AMERICAN ACADEMY 



porary stars ; Class II., stars undergoing large variations in periods 

 of several months ; Class III., irregularly variable stars undergoing 

 but slight changes in brightness ; Class IV., variable stars of short 

 period, like ^ Lyrce or 8 Cephei ; Class V., Algol stars, or those which 

 at regular intervals undergo sudden diminutions of light, lasting for 

 but a few hours. The third column gives tlie name of the discoverer, 

 and the fourth column the date. The fifth column gives the number 

 of nights on which each star was observed in 1883 by the observers, 

 whose initials are appended to the figures. These initials are placed 

 in alphabetical order, and are explained below. The last column con- 

 tains the names of other astronomers who are known to have observed 

 the corresponding stars since 1880. Some of these names have been 

 abbreviated as follows : Duner, D. ; Ilartwig, IT. ; Safarik, Sf. ; 

 Schmidt, Sm. ; Wilsing, W. 



The initials in the last column but one of Table I. refer to the 

 followincr series of observations : — 



C. This series is carried on by Mr. S. C. Chandler, Jr., at the 

 Harvard College Observatory. The telescope employed was made by 

 Mr. Clacey. Its aperture is 6^ inches, and the magnifying power 

 employed is generally 45 ; sometimes, 125 or 200. The observations 

 were begun in March, 1883, but their number has been greatly in- 

 creased since October. The present plan contemplates two or three 

 observations of each variable belonging to Class II. during every 

 month, whenever it is sufficiently bright to be visible. The obser- 

 vations are made by Argelander's method. Estimates of magnitude 

 are also made independently. 



H. These observations are made by the Rev. J. Ilagen, S. J., at 

 Prairie du Chien, Wisconsin. After the middle of November, 1883, 

 the observations were independently repeated by INIr. Zwack. The 

 instrument is a telescope by Merz, three inches in aperture. The ob- 

 servations are made by the division into tenths of the interval between 

 two comparison stars. A copy of all the observations has been re- 

 ceived at the Harvard College Observatory, and is available for the 

 discussion of the variations of any of the stars observed. 



L. These observations were made by Mr. H. A. Lawrence, and 

 will be mentioned below, under the heading U. 



P. These observations are made by Mr. II. M. Parkhurst, at 

 Brooklyn, N. Y., with a telescope made by Fitz, nine inches in 

 aperture. The magnifying powers employed are 56 and 150. Many 

 of tlie observations are made by Argelander's method, and the re- 

 mainder with photometric apparatus devised by Mr. Parkhurst, in 



