Drawing of a Thomson reflecting galvanometer from around 1900. <a rel="nofollow" class="external text" href="http://www.chss.montclair.edu/~pererat/mpersci.htm">Tom Perera's Scientific instrument collection</a> says it was Model 502, made by Elliot Bros., London. The vertical tube contains a fine silk fiber, which suspends a 1/2 in. mirror with small magnets on its back, seen in window, in the center of a coil of wire. A light beam reflected from the mirror lands on a scale and serves as a pointer. It has interchangeable coils of from 150 to 5000 ohms resistance. Alterations: removed caption, rotated image so it was vertical.
Norman Hugh Schneider
1913
Downloaded from <a rel="nofollow" class="external text" href="https://books.google.com/books?id=ZZ83AAAAMAAJ&amp;pg=PA13&amp;sig=v31U_QMaInWIfs6Q2g7aSCtkHrQ">Norman H. Schneider (1913) <i>Electrical Instruments and Testing</i>, Spon &amp; Chamberlain, New York, p.13 fig.8</a> on Google Books