PEASE, FRANCIS GLADHELM

(b. Cambridge, Massachusetts, 14 January 1881; d. Pasadena, California, 7 February 1938), astronomy.

Pease, the son of Daniel and Katherine Bangs Pease, received his education in Illinois. He attended high school in Highland Park and the Armour Institute of Technology in Chicago (now part of the Illionis Institute of Technology), where in 1901 he received a B.S. in mechanical engineering. Armour also awarded Pease an honorary M.S. in 1924 and D.Sc. in 1927, and he received another honorary D.Sc. in 1934 from Oglethorpe University. In 1922 he was elected a fellow of the Royal Astronomical Society.

Upon completing his formal education in 1901, Pease became a staff member of the Yerkes Observatory. There, with G. W. Ritchey, he studied problems in optics and instrument design, and carried out astronomical observations with the twenty-four-inch reflector . In 1904 he went to the Mount Wilson Observatory, where he remained as an instrument designer and astronomer until his death. He did, however, spend 1918 as chief draftsman in the engineering section of the National Research Council.

Pease’s combination of instrumental expertise and observational experience made him immensely important to the Mount Wilson Observatory, which was embarking upon the construction of several large instruments. He helped design the 60-inch and 100-inch reflectors, the 60-foot and 150-foot towers, and the 20-foot and 50-foot interferometers, as well as much of the auxiliary equipment used with these instruments. He was also responsible for solving many of the design problems of the 200-inch telescope. Aware of the immense potential of larger telescopes, Pease spent considerable time developing plans and publishing papers on the need for, and uses and difficulties of, such instruments.

Pease was associated with A. A. Michelson in the first determination of stellar diameters, using interferometers for the difficult measurement of fringes as a function of mirror separation. He also assisted Michelson and F. Pearson in redetermining the velocity of light and in repeating the Michelson-Morley experiment.

Pease’s direct spectrographic study with W. S. Adams and M. L. Humason of nebulae and star clusters enabled him to continue the measurements of rotations and radial velocities of spirals, which V. M. Slipher had begun in 1914 at the Lowell Observatory. In astronomical research Pease made important, although not pioneering, contributions; in instrument design, however, he was a leading figure of the twentieth century.

BIBLIOGRAPHY

I. Original Works. Pease’s key papers include “Radial Velocities of Six Nebulae,” in Publications of the Astronomical Society of the Pacific, 27 (1915), 239–240; “The Rotation and Radial Velocity of the Spiral Nebula N.G.C. 4594,” in Proceedings of the National Academy of Sciences2 (1916), 517–521; “Photographs of Nebulae With the 60-Inch Reflector 1911–1916,” in Astrophysical Journal46 (1917), 24–55; “Interferometer Observations of Star Diameters,” in Publications of the Astronomical Society of the Pacific, 34 (1921), 183; “On the Design of Very Large Telescopes,” ibid., 38 (1926), 195–207; “The Ball-Bearing Support System for the 100-Inch Mirror,” Ibid44 (1932), 257, 308–312; and “Measurement of the Velocity of Light in a Partial Vacuum,” in Astrophysical Journal82 (1935), 26–61, written with A. A.Michelson and F. Pearson, Some of his correspondence with G.E. Ha;e about designs for the 200-inch telescope are in the George Ellery Hale papers (1882–1937), Mount Wilson Observatory library, Pasadena, California.

II. Secondary Literature. Obituaries of Pease are W. S. Adams, in Publications of the Astronomical Society of the Pacific, 50 (1938), 119–121, with portrait; G. Stromberg, in Pacific Astronomy, 46 (1938), 357–359; and by an anonymous writer in Monthly Notices of the Royal Astronomical Society99 (1938), 312. For additional, related material see A. Pannekoek, A History of Astronomy (London, 1961). Pease’s contributions to Mount Wilson are discussed in Helen Wright’s biography of Hale, Explorer of the Universe (New York, 1966).

Richard Berendzen
Richard Hart