McDonald Observatory, the original unit in a complex that became one of the great observatory centers of the world, was built in the 1930s under the terms of a legacy from William Johnson McDonald (1844-1926), a Paris, Texas, banker interested in the stars. Though he lived frugally, McDonald was well educated, read science books as a hobby, and viewed planets through a small telescope. His will granted the University of Texas $800,000 to build an observatory and promote the study of astronomy. The site was chosen for its high ratio of clear nights, its 6,800-foot altitude, and its low latitude, which permits observation of southern skies. For its first 25 years, the observatory was operated mainly by astronomers from the University of Chicago and more recently primarily by the University of Texas. Until 1948, its 82-inch telescope was the second largest in the world, and its work and site led to the addition of other telescopes, including a 107-inch instrument sponsored jointly by the National Aeronautics and Space Administration, the National Science Foundation, and the University of Texas. Discoveries made there included interstellar polarization and the satellites of several planets.
