Blondlot, René-Prosper

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Blondlot, René-Prosper

(b. Nancy, France, 3 July 1849; d. Nancy, 24 November 1930)

physics.

Son of Nicolas Blondlot, a renowned physiologist and chemist, René Blondlot spent never a member of the Paris Academy of Sciences, he was named correspondant for the Section of General Physics in 1894. In addition, the Academy awarded him three of its most important prizes, chiefly for his experimental determinations of the consequences of Maxwell’s theories of electromagnetism.

In 1875 John Kerr discovered that birefringence was produced in glass and in other dielectrics subjected to an intense electrical field. With the aid of a movable mirror Blondlot established that in the oscillating discharge of a condenser the time-lag between the electrical phenomenon and the appearance Of the Kerr effect is less than 1/40,000 of a second. With Ernest Bichat he observed the same instantaneity for magnetic, rotatory polarization.

Using this same technique of a rapidly rotating mirror, Blondlot measured the velocity of electricity propagated through conducting wires. He sent simultaneous electrical charges through conducting wires, one of which was 1,800 meters longer than the other. Byphotographing the light from the resulting sparks successively reflected in a rotating mirror and then measuring the distance between the photographic images, Blondlot established that the speed of electricity in a conductor was nearly the same as that of light.

Blondlot received his greatest notoriety in the controversy over the existence of N rays. In the course of an attempt to polarize the newly discovered X rays, Blondlot claimed in 1903 to have found a new kind of invisible radiation, capable of being emitted not only from cathode ray tubes but also from many luminous sources, most notably from Auer burners. He named this new species of radiation N rays, in honor of the city of Nancy. No fewer than fourteen of his fellow scientists claimed also to have observed these N rays emanating from various animal and vegetable substances and, in the case of Jean Becquerel, from “anesthetized metals.” Because of the difficulty of reproducing the experiments, many scientists came to doubt the existence of Blondlot’s new ray. In 1904 the editors of the Revue scientifique undertook an examination of the entire matter and concluded that the positive experimental results had been the chimerical products of autosuggestion. Blondlot finally recanted and, probably as a result of the scandal, spent the rest of his life in relative obscurity.

BIBLIOGRAPHY

I. Original Works. Blondlot’s writings include Recherches expérimentales sur la capacité de polarisation voltaïque (Paris, 1881); Introduction è l’etude de l’electricite statique (Paris, 1885), written with Ernest Bichat; lntroduction a l’etude de la thermodynamique (Paris, 1888); Sur un électromètre astatique pouvant servir comme wattmetre (Nancy, 1889), written with P. Curie; and “.V” Rays, A Collection of papers Communicated to the Acadamy of Sciences, J. Garcin, trans. (London, 1905)

II. Secondary Literature. A brief eloge for Blondlot is in Comptes rendus hebdomadaires des seances de l’Acadamie des sciences, 191 (1 Dec. 1930), 80–81. For the N-ray controversy see Revue scientifique, 74 , no. 2 (July-Dec. 1904), 73–79, 545–552, 620–625, 705–709, 718–722, 783–785.

J. B. Gough