Two types of astatic galvanometer are in common use. In one, two needles with poles reversed are united to form a rigid system, in the other, a single suspended needle is employed, the directive force of the earth's magnetism being compensated by an immovable magnet suitably placed north or south of the needle. (Hauy's method.)
Proceedings of the Iowa Academy of Sciences
©1890 Iowa Academy of Science, Inc.
Andrews, Launcelot W.
"On a New Astatic Galvanometer with a Single Spiral Needle,"
Proceedings of the Iowa Academy of Science, 1(Pt. 2), 75-75.
Available at: https://scholarworks.uni.edu/pias/vol1/iss2/33