A dip needle is used to measure the vertical component of the earth's magnetic field. The first such needle was constructed in 1576 by Englishman Robert Norman, auther of The Newe Attractive i 1581. This was a treatise on lodestone, the naturally-occurring magnetic iron oxide. His work was soon followed, in 1600, by the De Magnete of William Gilbert (1540-1603), physician to Queen Elizabeth I. It was Gilbert who gave the name poles to the ends of a compass needle, because they pointed to the poles of the Earth. A dip circle is a more accurate form of a dip needle. A magnetic needle on a horizontal axis will lie horizontally only on the magnetic equator. Its dip or inclination increases as it is moved further from the equator, becoming almost vertical at the poles of maximum dip.
A magnetic balance is a device for assessing the strength of a magnet or magnetic field by using a balance beam and weights, or another mechanical arrangement, such as a spring. Magnetometers are also instruments for measuring the intensity of a magnetic field and can be used, for example, to find the horizontal component of the earth's magnetic field.

112 Dip Circle
115 Electromagnetic Balance
118 Ewles Torsion Magnetometer

Elec./Mag. Page

Dynamos