[1] JACQUES BESSON, _Des instruments mathématiques, et méchaniques, servants à l'intelligence de plusiers choses difficiles, & necessaires à toutes républiques_, 1st ed. (Orleans, 1569). [Also available in later editions in French, German, and Spanish.] [2] J. FOSTER PETREE, introduction, _Henry Maudslay, 1771-1831, and Maudslay Sons and Field, Ltd._ (London: The Maudslay Society, 1949). [3] _American Machinist_ (September 28, 1916), vol. 45, no. 13, pp. 529-531. [4] U.S. patent 10383 issued to Joseph Nason of New York, January 3, 1854. [5] U.S. patent 293930 issued to Charles Vander Woerd of Waltham, Massachusetts, February 19, 1884. [6] U.S. patent 1874592, filed June 8, 1929, issued to C. G. Olson of Chicago, Illinois, August 30, 1932, and assigned to the Illinois Tool Works, also of Chicago. [7] U.S. patent 1901926, filed February 16, 1928, issued to C. G. Olson of Chicago, Illinois, March 21, 1933, and assigned to the Illinois Tool Works, also of Chicago. [8] U.S. patent 1899654, filed August 31, 1931, issued to F. A. Ward of Detroit, Michigan, February 28, 1933, and assigned to the Gear Grinding Company of Detroit, Michigan. * * * * * Typographical Corrections Page 107: "... servants à l'intelligence de plusieurs choses difficiles, & nécessaires ..." (had "a," "plusiers," "necessaires") * * * * * CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY: PAPER 38 THE EARLIEST ELECTROMAGNETIC INSTRUMENTS _Robert A. Chipman_ ELECTROSTATIC INSTRUMENTS BEFORE 1800 123 INSTRUMENTING VOLTAIC OR GALVANIC ELECTRICITY, 1800-1820 124 ELECTRICAL INSTRUMENTATION, 1800-1820 125 OERSTED'S DISCOVERY 126 BEGINNINGS OF ELECTROMAGNETIC INSTRUMENTATION 126 CHRONOLOGY AND PRIORITY 127 ORIGINAL ELECTROMAGNETIC MULTIPLIERS 129 CONCLUSIONS 135 ACKNOWLEDGMENTS 136 _Robert A. Chipman_ THE EARLIEST ELECTROMAGNETIC INSTRUMENTS [Illustration: Figure 1.--MODELS OF VARIOUS ELECTROMAGNETIC INSTRUMENTS created by Schweigger, Poggendorf and Cumming in 1821, made for an exhibit in the Museum of History and Technology, Smithsonian Institution. (Smithsonian photo 49493.)] _The history of the early stages of electromagnetic instrumentation is traced here through the men who devised the theories and constructed the instruments._