Note 6 — AN UNIVERSAL DICTIONARY OF THE MARINE. (continued 3)

The wires of which the needle has hitherto been generally composed, were only hardened at their ends; now if those ends are not equally hard, or if one end be hardened up higher than the other, when they come to be put together, in fixing them to the card, that end which is hardest will destroy much of the virtue of the other; by which means the hardest end will have the greatest power in directing the card, and consequently make it vary towards its own direction; and, as the wires are disposed in the form of a lozenge, these cards can have but little force; so that they will often, when drawn aside, stand at the distance of several degrees on either side the point from whence they are drawn; for all magnetical bodies receive an additional strength by being placed in the direction of the earth’s magnetism, and act proportionably less vigorously when turned out of it. Therefore when these kind of needles are drawn aside from their true point, two of the parallel sides of the lozenge will conspire more directly than before with the earth’s magnetism, and the other two will be less in that direction: by this means the two former sides will very much impede its return, and the two latter will have that impediment to overcome, as well as the friction, by their own force alone.