ALBERT

Description:    Horizontal pendulum development was paramount in the birth of modern instrumental seismology and solid-earth tide study. This paper presents a revised history starting in the first part of the nineteenth century and culminating with Rebeur-Paschwitz’s masterpiece in its latter part. The first stage began with the invention of the horizontal pendulum by Lorenz Hengler in 1832. He was followed by several, mostly independent, inventors during the three decades from the 1850s to the 1870s, in particular Friedrich Zöllner in 1869–1872 who popularized this instrument. With the exception of an instrument designed by Alexander Gerard in 1851, all these preliminary pendulums were suspended with two wires. Slightly different forms of horizontal pendulums were invented in Japan by James Ewing and Thomas Gray in the early 1880s, based on bracket or conical suspensions. The merit of demonstrating the outstanding potential of high-sensitivity horizontal pendulums completely relies on the work of Ernst von Rebeur-Paschwitz between 1886 and 1895. He successively developed three models of pendulums, in collaboration with three different manufacturers: the Fecker pendulum in 1886, the Repsold pendulum in 1888, from which six copies were produced, and finally, the Stückrath two-component model in 1894, built in three copies. Based on the scrutiny of a large number of previously unexploited archives, the detailed chronology of Rebeur-Paschwitz’s achievements is presented. Archive, and in situ explorations allowed us to discover five out of the six original copies of the first Rebeur-Paschwitz’s Repsold pendulum previously unknown or thought to be lost. Content Type Journal Article Category Original Article Pages 1-29 DOI 10.1007/s10950-011-9272-5 Authors Julien Fréchet, Institut de Physique du Globe de Strasbourg, Strasbourg University/EOST, CNRS, 5 rue René Descartes, 67084 Strasbourg, France Luis Rivera, Institut de Physique du Globe de Strasbourg, Strasbourg University/EOST, CNRS, 5 rue René Descartes, 67084 Strasbourg, France Journal Journal of Seismology Online ISSN 1573-157X Print ISSN 1383-4649