OF ARTS AND SCIENCES. 395 



therefore be employed in fuLure chiefly iu determiniug the brightness 

 of the comparisou stars. 



Zk. The observations of Assistant G. Zwaek have already been 

 mentioned under the heading Iln. 



Zr. The observations of Assistant Zaiser have already been men- 

 tioned under the heading Iln. 



The summai-y of the progress of observation during 1884 is con- 

 tained in the hist column of Table I. The preceding columns are 

 repeated, after correcting some numerical errors, from the corresjjond- 

 iiig table in the statement published last year. The first column of the 

 left-hand page gives a provisional number for designating the star. 

 This number is taken from Schonfeld's Catalogue when the star occurs 

 there; in other cases, a letter is added to the number. Other letters 

 may be employed iu effecting additional intertwlation. The second 

 column contains numbers from the Photometric Catalogue called Har- 

 vard Photometry, and published iu A'olume XIV. of the Annals of 

 the Harvard College Observatory. The following columns contain the 

 usual designation of the star, its right ascension and declination for 

 1875, magnitude at maximum and nunimum, and period in days. 



The first column of the right-hand page repeats the number to be 

 used for the provisional designation of the star. The second gives the 

 class to which the star belongs, upon the system of classification em- 

 ployed in the Proceedings of the American Academy of Arts and 

 Sciences, XVI. 2-37. Upon this system, Class I. includes temporary 

 stars ; Class II., stars undergoing large variations in periods of several 

 months; Class III., irregularly variable stars undergoing but sliglit 

 changes m brightness; Class IV., variable stars of short period, like 

 /3 Lyrce or S 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 the name of the discoverer, and the 

 fourth column the date. 



The last column, as above stated, contains the number of nights on 

 which each star was observed by the astronomer whose designation is 

 attached to the number. A dash preceding a designation shows that 

 the star has been observed, but that the number of niglits has not been 

 furnished. The abbreviations employed have been explained above. 

 The letter K. is preceded by two numbers, the first of which relates to 

 observations made in 1883. 



Table I. is followed by a series of remarks containing observed 

 dates of maximum and minimum, and other information received from 

 the observers with regard to particular stars. 



