OP ARTS AND SCIENCES. 307 



order to effect an optical diminution of the aperture, without dimin- 

 ishing the brightness of the field, until the disappearance of the star. 

 The telescope being fixed, the pencil of rays is gradually intercepted 

 and slightly deflected by a prism, the proportion of the light being 

 determined by the time which elapses after the passage of the transit 

 wire by the star. Both accuracy and facility of reduction are much 

 increased by placing over the object-glass caps bounded by logarithmic 

 curves. A copy of the observations has been received at the Har- 

 vard College Observatory, and is available for the discussion of the 

 variations of any of the stars observed. 



S. These observations are made by Mr. E. F. Sawyer, at Cam- 

 bridgeport, Mass., by means of an opera-glass for the brighter stars, 

 and of a field-glass for the others. It is to be noticed that the obser- 

 vations of the star 95 b, made by Mr. Sawyer on twelve nights, con- 

 sist in the observation of twelve minima, each series usually including 

 a large number of comparisons. Mr. Sawyer has sent the results of 

 all his observations to the Asti-onomische Nachrichten. 



U. These observations were made by Professor Winslow Upton, 

 of Brown University, durhig an expedition to observe the total eclipse 

 of the Sun which occurred on May 6, 1863. The observations were 

 chiefly made on board the U. S. S. Hartford, but partly on Caroline 

 Island, in the Pacific Ocean. No instruments except a field-glass 

 were employed in the comparisons, which were made by the division 

 into tenths of the interval between two comparison stars. Most of 

 the observations were independently repeated by Mr. H. A. Lawrence. 

 The stars observed were all south of — 30° declination ; no account 

 has been received of any other observations of these southern stars 

 during 1883. 



Z. These observations were made by Mr. Zwack, and have already 

 been mentioned under the heading H. 



Although it is of course impossible to prepare a complete list of 

 stars suspected of variability, as distinguished both from known vari- 

 ables and from stars about the magnitude of which observers have 

 slightly differed, the attempt has been made iu Table II. to provide a 

 list of stars for the variability of which there is evidence enough to 

 make them interesting objects. When the variability of any of these 

 stars has been fully established, it will be very desirable to determine 

 their maxima, minima, periods, and light curves. In observing these 

 objects, the comparisons should be made either by Argelander's method 

 or by some other of sufficient precision to decide the question of vari- 

 ability. The mere estimation of magnitudes cannot suffice for this 

 purpose. 



