Humason (Milton La Salle)

Biographical Note

Milton La Salle (his middle name has also been cited as Lasell) Humason was a staff astronomer for the Mount Wilson [& Palomar] Observatories throughout his entire astronomical career. Humason is remembered chiefly for his collaboration with Edwin P. Hubble in the field of observational cosmology. Perhaps his most notable accomplishment, however, was his rise from mule-driver and janitor at Mt. Wilson to the position of astronomer with the lack of even a high-school education. It was a feat remarkable for the time and will probably never be matched.

Humason was born on August 19, 1891, in Dodge Center, Minnesota. His family moved west to California, and in the summer of 1905 he was taken to a summer camp on Mt. Wilson. At this time, the Mt. Wilson Observatory was not yet one year old, and there was a good deal of activity by the solar astronomers on the mountain top. Humason involved himself in this activity by quickly dropping out of high school in the fall of 1905 and within a few years becoming a mule driver. He would lead mule-powered wagons up the Mt. Wilson Toll Road carrying timber, iron, and other supplies for the construction of the telescopes and support buildings at the Observatory. It was as a mule driver that Humason met Helen Dowd, daughter of the Observatory's engineer, Merritt C. "Jerry" Dowd, in 1910. They were soon engaged and married one year later.

In 1910, Humason left mountain work and got a job as a foreman on a relative's ranch in La Verne, California. In 1917, however, Jerry Dowd told Humason that a janitor's job would be opening soon at Mt. Wilson Observatory. Knowing that the janitor's position at the Observatory could eventually involve duties such as relief night assistant on the telescopes, Humason took the offer. With the new 100-inch Hooker Telescope going into operation at the Observatory in 1919 and the need for more night assistants, Humason soon got to work with the telescopes. At about the same time, Hugo Benioff, a volunteer assistant at Mt. Wilson from Pomona College, showed Humason how to take photographic plates with the 10-inch astrographic camera on the mountain. Humason became so adept at this that Benioff soon recommended that Humason carry on the former's work in the fall. As Humason gained experience he also started taking plates for Harlow Shapley's observing program. And Humason used the 10-inch to look for W. H. Pickering's proposed Planet X in 1919. When Pluto was discovered in 1930, Seth Nicholson and Nicholas Mayall examined Humason's early plates and found that Pluto had been recorded on the photographs. Unfortunately for Humason, Pluto was so near the edge of the plates, and the images there were of such bad quality, that it is not surprising that Pluto was not discovered then. Humason's abilities with the telescopes on Mt. Wilson were so admired that by 1920 he was promoted from janitor to the staff of the Observatory's Stellar and Nebular Division. Humason continued his work with the 10-inch, observing clusters like M22 and also watching the Andromeda Nebula (M31) for novae. As Edwin Hubble's work on the spiral nebulae showed them to be distant galaxies, he initiated in the late 1920s a program of systematic observation of nebular redshifts. Obtaining usable spectra of the extragalactic nebulae, with their low surface brightness, would require the utmost expertise in observing skill. For this reason, it is not surprising that Humason was chosen to be Hubble's colleague. Humason developed and refined the techniques required to take exposures of up to forty hours (over several nights) with the 100-inch telescope. From the beginning of the redshift program until his retirement in 1957, Humason photographed spectra of approximately 600 galaxies. He used the 100-inch telescope to obtain these until the 200-inch Hale Telescope became available in 1949. During this time, Humason also applied his observing skill to projects on supernovae, old novae, and faint blue stars.

On October 1, 1948, Humason was appointed Secretary of the Observatory upon Alfred H. Joy's retirement. The duties of the Secretary involved handling the Observatory's public relations. This meant reading and often answering the various letters from the general public. The letters ranged from questions from high school students to requests for photographs to oddball theories of the universe from everyone imaginable. A colleague of Humason's, Robert S. Richardson, described the job: It was not an easy job by any means. One of his most onerous duties was answering the numerous phone calls and crank letters that came into the observatory. You have no idea of the number of people who seem to have nothing better to do than worry about whether the moon is in its orbit, or in denouncing such impostors as Newton and Einstein, and their wholly erroneous theories of gravitation (in contrast to their own entirely new rational theory). If you answer a letter of this kind, trying to explain the fallacy in their reasoning, you immediately get another one back demanding more information. Humason's policy was to answer every such letter once, but a second time --no. If you conscientiously answered them all, you would soon find that instead of working for the observatory in Pasadena, California, you were spending most of your time working for some victim of delusional insanity in Pasadena, Newfoundland. Humason had an innate knowledge of human nature, and practical ideas on how to handle people in a considerably better manner than most members of the staff. Humason remained as Secretary until his retirement in 1957. Most of the material in this collection dated 1948 and later is correspondence like that mentioned above. There are occasional personal and scientific letters but these are very few compared to the letters from the public. The correspondence ends in 1952 and any after that time has not yet been uncovered.

Humason never earned a degree until, in 1950, an honorary doctorate was conferred on him by the University of Lund in Sweden. He retired on July 1, 1957 and soon moved to Mendocino, California. While in retirement he was occasionally consulted by the astronomers at the Observatory on questions dealing with the telescopes, especially the 100-inch. He died at his home on June 18, 1972. His skill at obtaining usable spectra of the most distant galaxies in association with Edwin Hubble's observing program will ensure Humason's place in the history of astronomy.

From the guide to the Milton La Salle Humason Papers, 1930-1952, (The Huntington Library)