ACAMMY OF SCIENCES] BIOGRAPHY 11 



was usually ready before the sun had set, and impatiently waiting until the darkness should be 

 sufficient for him to "get the parallel" for the thread of the micrometer before he could observe 

 faint objects. During the day preceding one of his nights, his associates in the observatory 

 were generally conscious of his keen anxiety for a clear sky, as evidenced by a frequently 

 repeated nervous cough, which was always worse if the prospects for the night were unfavorable. 



It was a marvel to all of us that his bodily strength was equal to the tasks which he put 

 upon himself. He was accustomed to get on with very little sleep, and if the night was cloudy 

 he could never trust himself to relax, but was constantly on the lookout for a possible clearing 

 of the sky. Nevertheless, he often appeared in his office by 7 o'clock in the morning, and began 

 work on the reduction of his observations of the night before. He was a very painstaking and 

 accurate computer, and it was seldom that the positions of any celestial objects measured by 

 Mm required correction for any numerical errors after they were published. From about 1906 

 he had the valuable assistance of Mrs. Barnard's niece, Miss Mary R. Calvert, who helped in 

 his computations and in his correspondence, and in filing and cataloguing the great number 

 of photographs and reduction sheets which he accumulated. The bibliography at the end of 

 this paper is based upon a card catalogue which she had prepared and kept up to date. 



The nebulous regions of the Milky Way were always of much interest to Mr. Barnard, and 

 he early discovered on his photographs great nebulous areas which had not been previously 

 suspected. He investigated many cases of nebulous stars, or of stars which seemed to be 

 involved in "nebulosity," a word which he commonly used to describe vague and indefinite 

 nebulous matter, generally of great extent. In some cases the term may represent a real dis- 

 tinction between a gaseous nebula and one which yields a continuous spectrum; in other cases 

 it may denote finely divided matter reflecting light from a stellar source. The following 

 quotation is from one of his early papers, entitled " The great nebula of Rho Ophiuchi and the 

 smallness of the stars forming the groundwork of the Milky Way." 1 



For many years this part of the sky troubled me every time I swept over it in my comet seeking; though 

 there seemed to be scarcely any stars here, there yet appeared a dullness of the field as if the sky were covered 

 with a thin veiling of dust, that took away the rich blackness peculiar to many vacant regions of the heavens. 

 This was full}' fifteen years ago, at Nashville, Tennessee, when I searched for comets with a five-inch refractor. 



After going to the Lick Observatory, I still noticed this peculiarity of that part of the sky, and finally found 

 that two small stars north of Antares were involved in nebulosity and that the whole region seemed to be covered 

 with a very weak diluted nebulosity. . . . 



This part of the sky coming within the sphere of my work in photographing the Milky Way, on March 23, 

 1895, I made a photograph of it with 2 h 20 m exposure. The resulting negative showed a vast and magnificent 

 nebula, intricate in form and apparently connected with many of the bright stars of that region, including 

 Antares and Sigma Scorpii. 



Professor Barnard had early formed a plan for securing a photographic chart of the Milky 

 Way, and he was quick to accept an invitation from Professor Hale to bring the Bruce telescope 

 to Mount Wilson for photographing particularly the southern portions of the Galaxy, in so far 

 as they could be reached from that latitude. The telescope was, accordingly, transported to 

 Mount Wilson, under the auspices of the Carnegie Institution of Washington, in January, 1905, 

 and Professor Barnard spent about nine months on the mountain, engaged in this work. The 

 telescope was back in its own dome at Williams Bay before the end of the year, and for the next 

 17 years was always available for Mr. Barnard's use, being seldom employed by any other 

 observer. 



In 1907 the Carnegie Institution undertook to publish the Atlas of the Milky Way when 

 it should be ready, and during several years search was made for the best mode of reproduction 

 of the pictures. Careful experiments were undertaken by experts in photogravure, and with 

 the heliotype process, but the degree of perfection desired could not quite be attained. Finally, 

 Mr. Barnard accepted the suggestion that photographic prints would most faithfully reproduce 

 the wonderful details of the original negatives. Accordingly, with infinite pains, he made posi- 

 tives from the original negatives and then second negatives from which the prints could be pre- 

 pared. In this way, the contrast in faint regions was increased and details were brought out 



1 Popular Astronomy, 5: 227, 1897. 



