XXU CARNEGIE INSTITUTION 



Each of the numerous investigations is of importance in carrying 

 forward the work going on in the observatory, but they do not ap- 

 pear to be upon sufficiently definite and specific problems, as given in 

 his report, to permit of a distinct statement, in most cases, of the 

 progress of the work under the Carnegie Institution grant. 



Professor Pickering reports that in forming a corps of observers 

 to study the photographs, time and mone}^ being limited, it was 

 difiicult to decide what subjects to select from this vast amount of 

 material. A number of problems have accordingly been studied 

 which serve to illustrate the various investigations which might be 

 undertaken. Abridged results of a portion of these were promptly 

 published in the Harvard Observatory Circulars Nos. 69 and 70. 

 The principal researches carried on are as follows : 



1. Eclipses of Jupiter's satellites. 



2. Light curves of Algol variables. 



3. Position and brightness of stars in clusters. 



4. Observations have been made of the changes in light of 9 vari- 

 able stars of long period, during several years before they were 

 discovered, 



5. Early observations of stars of the Algol type and other varia- 

 bles of short period. 



6. Transit photometer. 



7. Nova Geminorum. 



8. Variations in brightness of Eros. 



9. Proper motion of stars, 



10. Missing asteroids. 



11. Man}^ images of interesting objects like new stars, variables, 

 and asteroids doubtless appear on the photographs. An examina- 

 tion has accordingly been made of several of the plates to determine 

 whether it would be advisable to examine a large number of them 

 systematically for the discovery of such objects. 



Wm. M. Reed, Princeton Observatory, Princeton, N. J. Grant 



No. 54. For pay of two assistants to observe variable stars. 



$1,000. 



Abstract of Report. — Owing to the difiiculty of obtaining an ob- 

 server, work was not begun till March i . During the seven months 

 from March i to October i, the 23-inch telescope of the Halsted 

 Observatory, exclusively for photometric work, was used on every 

 clear night from early in the evening until daylight. In all, 9,015 

 observations were made on about 50 different stars. 



