Edward Emerson Barnard and his Atlas of the Milky Way
This rendering of E.E. Barnard's 1927 "An Atlas of Selected Regions of the Milky Way" raises one of the gems of astronomical literature out of near obscurity, an obscurity caused by the small number of copies (probably as few as 700) of the Atlas that were printed in 1927. Obscure also because its initial distribution was mainly only to scientific libraries.
Edward Barnard was one of the grandest and most honored observational astronomers of his time, working in the last two decades of the nineteenth century and the first two of the twentieth. He was born into poverty in Nashville , Tennessee in 1857. His father had died before he was born, leaving his mother and himself with no income. To help attain the bare necessities for existence, Barnard as a boy of nine began an apprenticeship as a photographer's assistant in Nashville, a post he kept for 17 years during which he learned the then new and arcane art and science of the photographic process, the cameras, its lenses, and the processing of the photographic glass plates upon which the early photographic emissions were deposited.
He early became acquainted with the night sky as an amateur star gazer, and became so enthralled with the stars and their displays as to begin a life consumed by the study and practice of astronomy. It was an obsession that never left him, even as he eventually used the world's two largest telescopes of the time, the 36–inch refractor at the Lick Observatory and the 40–inch refractor at the Yerkes Observatory, as a staff astronomer at each.
Barnard had saved his small yearly earnings as the photographer's assistant in Nashville to purchase a telescope of 5–inch aperture for $380 (a very large sum at the time) sometime in the late 1870's. With it he began his systematic observations of the night sky, soon discovering four comets in the short time of three years. At the time, a wealthy patron of astronomy had offered $200 for every new comet discovery, and Barnard collected the award five times, after with the award was withdrawn because Barnard was discovering so many that the fund had become depleted.
In those days, great fame was attached to comet discoveries, and E.E. Barnard, at age 25, had become one of the most famous of American observational amateurs. So much so that in 1887 Professor Edward S. Holden, director designate of the nearly completed Lick Observatory in central California, offered Barnard a staff astronomer's position at Lick to begin work of that observatory with its 12–inch and almost completed 36–inch refractors, the latter was to be the largest in the world. There were three other appointees in the first group, one a double star observer who was also an amateur (S.W. Burnham), one a meridian circle observer, and one a spectroscopist. Barnard was the photographer, and also an expert in visual observations at the telescope.
He had had virtually no formal schooling. It had amounted to only two months before his photographer's apprenticeship began. He remained self taught during these years, although he eventually did enroll as a special student for several semesters at Vanderbilt in Nashville between 1883 and 1887, as both a student and an instructor in practical astronomy, which by that time, at nearly 30 years of age, he had become an expert. Hence, he went to Lick as a self–trained amateur, turning into a professional immediately on joining the Lick staff.
Barnard's fame continued to grow at Lick when he discovered more comets, (eventually he would discover 20 over the course of his career, probably still the world's record for a singe observer), and especially with his discovery by visual observations of the fifth moon of Jupiter with the 36–inch refractor, a feat that could only be done with the largest telescopes with the longest focal lengths because the fifth moon is faint and is close to the blazing light from the parent planet.
Barnard's love for the sky in its wide–angle sweeping glory remained with him even as he had observing privileges and duties with the two refractors that necessarily have such restricted fields of view due to their very long focal lengths. Because of his interest in wide–field astronomy, soon after his arrival at Lick Barnard began photographic experiments with a short focal length camera lens that had been used for commercial portraiture photography in a studio. Barnard had acquired the lens and adapted it to photograph the sky by strapping the camera that he built around it, to an equatorially mounted small telescope that could be driven to track the stars as the earth turns. He began a series of portrait photographs of the Milky Way, of comets, and asteroids that was to occupy him at Lick for the remainder of his eight year stay there. This large collection of photographs was eventually published in 1913 by the Lick Observatory, nearly 20 years after Barnard had gone to the Yerkes Observatory of the University of Chicago in 1895 as a Professor of Practical Astronomy.
Although the Lick 5–inch portrait lens in Barnard's hands had produced excellent results for wide angle views of the Milky Way, an even superior study of the Galaxy could be undertaken if a larger, more exactly figured lens could be employed. To this end, Barnard contracted for a 10–inch photographic telescope to be built by the famous optical firm of John A. Brashear. The telescope was a compound of three separate telescopes, one a 10–inch "doublet" of 50–inch focal length, one a 6 ½ inch lens of 35–inch focal length, and a 3–inch guiding refractor, all mounted into a single structure to form a powerful photographic survey instrument. This is the famous Bruce telescope with which Barnard would make photographs for the Atlas that are reproduced here.
Forty of the 50 fields of the Atlas were obtained during a nine month stay at Mount Wilson in 1905. At the invitation of George Ellery Hale, director of the newly founded Mount Wilson Solar Observatory of the Carnegie Institution of Washington, Barnard had transported the Bruce telescope to the clear mountain side with its steady atmosphere (good seeing, which means an absence of turbulence).
Funds to publish the Atlas had been guaranteed by the Carnegie Institution in 1907. However, Barnard, ever the perfectionist, worked for many years on the assembly and the descriptions of the photographs, and on the inspection of more that 35,000 photographic prints that were required for the 700 copies of the Atlas that eventually would be printed. However, he did not complete the task by the time of his death in 1923. The work was finished in the form you see here by Edwin B. Frost, then director of the Yerkes Observatory, and by Barnard's niece Mary R. Calvert. This two volume Atlas, one volume of the photographs and the other a description of each field, was finally published by the Carnegie Institution in 1927 as a Carnegie Publication number 247.
The photographs in this Atlas remain a valuable data source for studies of the Milky Way, its star clouds, the numerous open clusters, and especially for the dark regions of the Barnard dark clouds, first made manifest in these photographs. The dark clouds proved to be singularly important in the discovery of dark matter between the stars, rather than voids in the heavens. Barnard was the first astronomer to provide this decisive evidence for their existence from these photographs.
Enjoyment of the Atlas can be had on two levels. One is the pictorial beauty of the star clouds and the dark markings due to interstellar dust blocking the star light behind them. The other is that of the professional astronomer, yet today, for studies of the large scale structure of the Milky Way in a way that needs no description, except to note that the value still remains.
Barnard passed to his reward in 1923, four years before the Atlas was issued, completing the promise made in 1907 by the Carnegie Institution to sponsor it by providing the publication costs.
E.E. Barnard was the last of the great visual observers and the first of the long line of photographic atlas makers with wide–angle telescopes. He remains in memory as a prime example of a self–taught amateur who became one of the internationally known pioneer astronomers as the United States was developing into a major player on the world–wide astronomical scene 100 years ago.
Allan Sandage, PhD