Dipping Needle
a magnetized needle, moving in a vertical plane, on an axis which passes at right angles exactly through the center of gravity.
When thus mounted it will, if placed anywhere not in the magnetic equator, dip or point downward. The position of the magnetic pole can thus be determined from the intersection of two or more lines formed by making experiments with the dipping needle at various places.
The inclination or dip of the magnetized needle was not known to the Chinese, who had discovered its variation during the 12th century. This element of ter- DIPTERA restrial magnetism appears to have been discovered by Robert Norman, a compass-maker of Ratcliff, London, who detected the dip, and published the fact in 1576. He contrived the dipping needle, and found the dip at London to be 71° 50'. Sir James Ross reached the magnetic pole, lat 70° 5' 17" N., and lon. 96° 46' 45" W., on June 1, 1831. The amount of dip was 89° 59′.