Brace, De Witt Bristol

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Brace, De Witt Bristol

(b. Wilson, New York, 5 January 1859; d. Lincoln, Nebraska, 2 October 1905)

optics.

De Witt Bristol Brace, professor of physics and specialist in optics at the University of Nebraska, is best remembered for his experimental test of the Lorentz-Fitzgerald contraction hypothesis in 1904. He received his bachelor’s degree from Boston University in 1881 and went on to graduate study at the Massachusetts Institute of Technology and Johns Hopkins University. In 1883 his admiration for Kirchhoff and Helmholtz took him to Berlin, where he wrote a doctoral dissertation on magneto-optical effects. In 1888, shortly after his return to the United States, Brace became professor of physics at the University of Nebraska, where he remained until his death. He was survived by his wife of four years, Elizabeth Russell Wing of Massachusetts. Brace was a member of the American and British Association for the Advancement of Science.

For eight years Brace was the entire physics department at Nebraska and had little opportunity for research until the faculty was expanded in 1896; then, however, he began a series of experiments on the effect of various external factors, such as magnetism (the “Faraday effect”), pressure, and strain on light passing through a transparent medium. In the course of this research he invented several new instruments, including a spectropolariscope and a spectrophotometer which today bear his name.

In 1904 the opportunity arose for Brace to apply the extremely sensitive optical techniques he had developed to one of the crucial problems of his day. Two years earlier, Lord Rayleigh had proposed that the Lorentz-Fitzgerald contraction, if it existed, might produce an observable double refraction in a moving transparent medium. Rayleigh made experiments in which he failed to find the predicted effect, but his work was not quite accurate enough to be conclusive. Brace pointed this out and reconducted the investigation in his own laboratory, establishing beyond a doubt the absence of double refraction caused by movement of the refracting medium through the ether. This did not disprove the contraction hypothesis, but Brace at first believed that it did. Joseph Larmor showed that double refraction need not result from Lorentz contraction if matter is composed of electrically charged particles that contract in the same proportion as large bodies; he thus saved the Lorentz hypothesis and gave the electron its status as a fundamental particle of matter.

Brace remained interested in the problems of contraction, and in 1905 performed experiments to detect higher-order effects that might clear up the issue. Death kept him from seeing its final resolution in Einstein’s theory of special relativity.

BIBLIOGRAPHY

I. Original Works. Articles by Brace include “Observations on Light Propagated in a Dielectric Normal to the 1 Lines of Force,” in Philosophical Magazine, 44 (1897), 342–349; “Description of a New Spectrophotometer…,” ibid., 48 (1899), 420–430; “Observation on the Circular Components in the ‘Faraday Effect,’” in Nature, 62 (1900), 368–369; “A Sensitive-strip Spectropolariscope,” in Philosophical Magazine, n.s. 5 (1903), 9; “Double Refraction in Matter Moving Through the Ether,” ibid., n.s 7 (1904), 317–328; and three articles on tests for the “ether drift,” ibid., n.s. 10 (1905).

II. Secondary Literature. Articles relating to Brace’s work are Joseph Larmor, “On the Ascertained Absence of Effects of Motion Through the Aether…,” in Philosophical Magazine, n.s. 7 (1904), 621; and Lord Rayleigh, “Does Motion Through the Aether Cause Double Refraction?,” ibid. (1902).

The only substantial biographical material about Brace is found in the Dictionary of American Biography, II, 540, and Who’s Who in America, 1903–1905. His role in the Lorentz contraction controversy is discussed in Florian Cajori, A History of Physics (repr. New York, 1962), p.378. For bibliography, see the Royal Society Catalogue of Scientific Papers, XIII, 757, and Poggendorff, V, 157.

Eugene Frankel