Elementary natural philosophy : designed for high schools and academies (1881)
Griffin, La Roy F. (La Roy Freese), 1844-1916 · Philadelphia : Sower, Potts & Co. · leaf 240
ment. A telescope is frequently placed above the needle,when the instrument becomes the Surveyors Transit. 782. The Mariners Compass, Fig. 277, has a card at-tached to the needleand moving with it.This card is dividedinto thirty-twopoints calledRhombs, and amark is made onthe box in the di-rection… … THE DIPPING NEEDLE. 231 keeps the compass uniformly horizontal.* The needle isbalanced before magnetization, and a light movableweight is attached to overcome the effects of Inclinationand keep the needle uniformly horizontal. This is essen-tial to delicacy. 783. The Dipping Needle. If a carefully…
Physics
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