49 o THE POPULAR SCIENCE MONTHLY. 



surement, and a circular was distributed among astronomers requesting 

 estimates of magnitudes of the same stars for comparison with each 

 other, and with the results of the measurements made here. A series 

 of measurements of all the planetary nebulae has also been undertaken. 

 This work with the great equatorial has necessitated the invention of 

 a number of new photometric instruments, which have been devised 

 by Professor Pickering and his assistants. 



For nearly eight years Professor Rogers has been engaged upon 

 one of the largest astronomical undertakings that has been successfully 

 completed in this country. This is the observation with the meridian 

 circle of the zone of eight thousand stars, between fifty and fifty-five 

 degrees north, undertaken by this Observatory as its share in the deter- 

 mination of the position of the stars of the northern hemisphere. The 

 observations were finished about a year ago, but some years will be 

 required to complete the reduction and publication of this work. 



The total number of observations for 1879 with the meridian circle, 

 including about six hundred for the Coast Survey, was nearly three 

 thousand. The scientists at the Observatory are now engaged in the 

 task of determining the light of all the stars visible to the naked eye 

 in the latitude of Cambridge. The meridian is used in observations 

 like a transit instrument in connection with a new and elaborately 

 designed photometer. 



At the Museum of Comparative Zoology the staff of specialists is 

 almost entirely occupied in the classification and arrangement of dif- 

 ferent collections and the publication of the results of their researches. 

 The most important accessions during 1878 and 1879 are the extensive 

 collections of the Blake dredging expedition, and the collections of 

 birds, mammals, reptiles, and fishes, made by Mr. Garman at St. Kitts, 

 Dominica, Grenada, Trinidad, St. Thomas, and Porto Rico, after he 

 left the Blake. The Blake collections and specimens from the 

 entomological, conchological, and ornithological departments are in 

 the hands of well-known specialists for final investigation. Of the 

 extensive work in progress it is impossible to give any details. The 

 results are embodied in the extensive publications of the museum. 

 Five volumes of bulletins have been published, averaging about a 

 dozen papers each. The quarto publications will hereafter be issued 

 as memoirs. The catalogues thus far published have been collected 

 into Volumes I.-IV. of the memoirs. Five volumes of memoirs and the 

 first part of the sixth have already appeared. The second part of the 

 sixth and Vol. VII. are now in course of preparation or in press. Vol. 

 VI. contains the great work upon which Professor Whitney is now 

 engaged, "The Auriferous Gravels of the Sierra Nevada of Califor- 

 nia." The Sturgis Hooper Professorship of Geology, held by Professor 

 Whitney, is noticeable as being founded solely for original research. 



The dredging operations of the Coast Survey steamer Blake have 

 not only aided zoological science by the information obtained in regard 



