London: Taylor & Francis, 1904. First edition, very rare offprint, of this experiment in which Brace measured a double refraction in a moving transparent medium which Lord Rayleigh had predicted was a consequence of the Lorentz-Fitzgerald contraction. This hypothesis, that bodies contract in their direction of motion, led to the Lorentz transformations of special relativity.
Rare offprint issue of the Brace experiment - the first optical experiment measuring the relative motion of Earth and the luminiferous aether which was sufficiently precise to detect magnitudes of second order to v/c. The Brace experiment was of great importance for the development of the Lorentz transformation and consequently of the theory of relativity.
“De Witt Bristol Brace [1859-1905], 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 ... 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.” (DSB).
Offprint from: Philosophical Magazine, series 7.volume 40 pp 317–329, original pink wrappers, pp  318329 [3:blank], dine and clean - an excellent copy.