Note 10 — CHAPTER 3 PIONEERS IN ELECTROMAGNETIC THEORY
Reading edition
One of the first electrical experimenters to devise the instrument known as a “galvanometer” was Professor Schweigger, of Halle. There are now eight or more varieties of this instrument (or apparatus) in use. It enables the investigator to measure extremely minute electrodynamic actions, or the very weakest intensity of an electric current, as well as to detect its presence or direction, usually by the deflection of a magnetic needle.