John Scoville Hall, director emeritus of the Lowell Observatory, died of heart failure on October 15, 1991, at his home in Sedona, Arizona. Hall was born in Old Lyme, Connecticut, the son of Nathaniel and Harriet Hall. Nathaniel Hall was a farmer and candy manufacturer; Mrs. Hall was a graduate of Wellesley College. John Hall attended Morgan High School; but apparently had little contact with astronomy until his sophomore year at Amherst College where he enrolled in an astronomy course taught by Warren K. Green. Hall's serious interest in astronomy began with this encounter. He accompanied Green to an AAS meeting at Columbia University during his junior year; and, when Hall was a senior, Green helped him obtain a scholarship for graduate study at Yale University.
Hall studied at Yale under Frank Schlesinger, Dirk Brouwer, and Jan Schilt from 1930 to 1933. His Ph.D. thesis concerned near-infrared photometric measurements of stars using a photoelectric cell custom built by C. Holden Prescott of Bell Labs. Taking his cue from Prescott, Hall was the first to cool a photocell with dry ice to reduce the dark current to a sufficiently low level that astronomical measurements were possible. The results of John Hall's thesis and an excellent description of his photometric apparatus are found in Ap.J. 79, 145, 1934.
Following graduate study, Hall moved to Columbia University for a year and then on to Swarthmore. During his second year at Swarthmore, he married Ruth Chandler, whom he had met while still at Yale. The Halls ultimately had two children: Richard, who is currently an astronomer at Northern Arizona University in Flagstaff, and Carolyn Smith, who resides in Sedona.
Throughout his career, John Hall's research centered around the use of photoelectric techniques. He was the first to use a photocell to scan stellar spectra (Ap.J. 84, 369,1936) and the first to use a wire grating to isolate spectral regions for relative photoelectric spectrophotometry (Ap.J. 94, 71, 1941). His work extended knowledge of the wavelength dependence of interstellar absorption out to approximately 1 micron. In 1949, John Hall and Albert Hiltner discovered the polarization of starlight by the interstellar medium (Science 109, 165, 1949). Polarization measurements of a wide variety of objects ranging from galaxies to the Moon occupied much of John Hall's research for the remainder of his career. He also worked with Merle Tuve, Kent Ford, and William Baum in the development of the Carnegie image tube, a device which was widely used as an intensified imaging detector prior to the advent of CCDs.
In 1938, Hall returned to his alma mater, Amherst College, where he continued his research and, for a time, operated a lab in which he built his own photocells. Then, following the outbreak of World War II the Hall family moved in 1942 to Cambridge, where John participated in the development of search and height-finding radars at the MIT Radiation Laboratory. His book, Radar Aids to Navigation, was published by McGraw Hill in 1947. Returning to Amherst in 1946, he taught physics for two years. This interval was the only time in his career that Hall assumed the role of a teacher.
In 1948, John Hall became director of the Equatorial Division of the U. S. Naval Observatory in Washington, D. C. Much of his early work on polarization of starlight was done in Washington with the USNO's 40-inch telescope. However, because observing conditions were so poor at this urban, low-altitude site, Hall suggested that the telescope be moved to a more favorable location. He ultimately selected a site west of Flagstaff, Arizona, and the telescope was moved there in 1955. The Flagstaff Station of the U. S. Naval Observatory, which Hall founded, is now also the home of the Navy's 61-inch Astrometric Reflector.
Hall was appointed director of Lowell Observatory in 1958. He remained in this position for 19 years, during which time he guided the Observatory through an unprecedented expansion in facilities and a notable strengthening of the research staff. Relocation of the 69-inch Perkins Reflector from Delaware, Ohio, to Lowell's newly established dark-sky site at Anderson Mesa was instigated by Hall. Also during his tenure, the Planetary Research Center was founded at Lowell with NASA sponsorship. In 1970, a versatile new 42-inch telescope was installed at Anderson Mesa—a telescope that twenty years later was renamed the John S. Hall Telescope in honor of the former director. These three major additions to the Observatory's research arsenal are only a few of the facilities now in operation at Lowell which date from the time of Dr. Hall's directorship. Roger Lowell Putnam, for forty years trustee of Lowell Observatory, noted in a 1968 letter to his director "It (Lowell Observatory) has become under your leadership a growing and viable force in astronomy, which it had ceased to be when you first became director." The last phrase of this statement is perhaps a bit harsh, but the overall sentiment of Putnam's message is true.
John Hall was a friendly, gentle man who usually had a smile on his lips and a twinkle in his eye. He was always ready with a word of encouragement or a helpful idea. When a new staff astronomer at Lowell Observatory clumsily broke one of the director's photomultipliers, Dr. Hall simply told the young man, "If you never make mistakes, you aren't doing anything."
Hall was an athletic person who at Amherst was a member of championship soccer and track teams. In fact, his 1929 pole-vaulting record of 11 feet 7 inches stood at the college for several years. Throughout his life, he was also an accomplished tennis player and sailor. His wit and good humor are well illustrated by a sailing incident which occurred near the end of Hall's tenure at Lowell Observatory. Most summers, Dr. and Mrs. Hall would return to the Hall family farm at the mouth of the Connecticut River near Old Lyme. Hall and his brother maintained a sailboat there. One day, Lowell astronomer Nat White and family were visiting the Halls at the farm, and John was preparing to take them for a sail. Hall was boarding the boat, Nat inquired "How deep is it here?" At that moment, Hall lost his balance and tumbled overboard. He emerged, standing with the water level near his waist, and calmly replied, "About this deep!"
As director, Dr. Hall opened the facilties of Lowell Observatory to astronomers from around the world. He took particular pleasure in introducing visiting observers from the cloud-shrouded climes of Europe, Scandinavia, and Scotland to the clear, dark skies of northern Arizona. Aina Elvius, Krysztof Serkowski, Mikolaj Jerzykiewicz, Alois Purgathofer, Karl Rakos, Tomas Pettauer, David Clarke, Ian McLean, and a string of Scandinavian graduate students came to Lowell for extended stays at Hall's invitation. These individuals, together with a steady stream of astronomers from Ohio State University, the Carnegie Institution, the U. S. Naval Observatory, and elsewhere, helped produce a vibrant astronomical community in Flagstaff. Most of this increased activity is traceable in one way or another to the initiatives of John Hall.
In the course of his long career, Hall was a councilor of the American Astronomical Society from 1959 to 1962 and vice president of the Society from 1963 to 1965. He served as president of Commission 16 and vice president of Commission 9 of the International Astronomical Union and was on the Space Sciences Board of the National Academy of Sciences for two years. Hall also served on NASA's Lunar and Planetary Missions Board. Amherst College, Ohio Wesleyan University, and Northern Arizona University each awarded honorary doctorates to John Hall.
Towards the end of Hall's astronomical career, he became increasingly concerned with social and environmental issues. He experimented with the development of inexpensive, easily constructed solar water heaters for use on nearby Indian reservations. He also conducted a long series of measurements of horizontal extinction with the objective of establishing a baseline against which any subsequent deterioration of visibility due to increasing coal-fired production of electricity in northern Arizona could be measured. After retirement, John Hall maintained an active interest in things astronomical. He presented historical papers on the work of V. M. Slipher, John A. Miller, A. James Robertson, George Ritchey, and Henri Chrétien at meetings of the American Astronomical Society and the Astronomical Society of the Pacific. Hall served as an honored and valued member of the Lowell Observatory Advisory Board until his death.
Those of us who knew John Hall were privileged. He taught us by example the true meaning of the word "gentleman."
Photo (available in PDF version): John S. Hall at the 40 in. Ritchey-Chretien telescope of the U.S. Naval Observatory in Washington, D.C., about 1950