THE LAW OF THE LAND. VII. THE NORTH STAR. By Wm. Arch. McClean. OUR title is somewhat on the order of Josh Billings's lecture on milk. The subject was dismissed with the reflection that the best thing on milk is cream. The most valuable star in the heavens for the purposes of the inhabitants of earth is the North Star, and with this and a few other casual remarks we will dismiss our title. There is some thing fascinatingly mysterious about that great bright star that has proved the faithful friend and guide of mariners. The north star might be said to be the brilliant jeweled head of the pole or axis of the earth, blaz ing this information for the use and benefit of mankind. The axis of the earth points to the north star. For practical purposes, the north star is observed for purposes of ascertaining the axis, the true north. The magnetic needle of the compass points to the north, to the axis that points to the north star. What has the magnetic needle to do with it? Ah, that's the rub. It has everything to do with our story, so we are compelled to dismiss our fascinatingly mys terious title. We all know and have seen that wonder ful instrument, a compass, with its poised needle always swinging and vibrating to the north. We know that there is a mariner's compass and a compass used for land sur veying. Now this quivering little needle points to the true north, the axis of the earth, and it does not so point. This needle is as contradictory as an Irish bull. On certain lines upon the earth's surface called lines of no variation, the needle points toward the pole. Such a line at the present time passes near Wilmington, N.C., Charlotteville, Va., and Pittsburg, Pa. When
the needle points to the north, on these lines of no variation, it is the true north, the pole, the axis, the north star. However, on the eastern side of this line the variation of the needle is toward the west, increasing in amount with the distance from it. On the western side the variation is toward the east. Take for instance the line of no variation above mentioned. The variation of the needle at New York City is six degrees west, while at the Pacific coast it is between fifteen and twenty degrees east. This variation undergoes a progressive change in amount, and after long periods changes in direction, vibrating, in fact, be tween certain limits. These lines of no variation are constantly slowly changing. InLondonin 1575 the variation was easterly eleven degrees, fifteen minutes, in 1657 it was nothing, then it slowly advanced to its maximum in 181 5, twenty-four degrees, seventeen minutes and eighteen seconds westerly. In the Eastern States the north pole of the needle is moving westward slowly. One can readily see the need of great care in surveying. The surveys should al ways be referred to the true meridian, or the date of the survey be indicated so that such reference may at any time be made. The variation of the needle from the true merid ian is corrected by allowing for the amount of this variation as established for the place and time, or as determined by observations made for the purposes at the time. The exact cause of the continued shifting of the needle of the compass is as yet a matter of speculation with science. This variation becomes a matter of great
