This section is from "Scientific American Supplement Volumes 275, 286, 288, 299, 303, 312, 315, 324, 344 and 358". Also available from Amazon: Scientific American Reference Book.
[Footnote: From Proceedings of the Association of County Surveyors of Ohio, Columbus, January, 1882.]
The following process has been used by the undersigned for many years. The true meridian can thus be found within one minute of arc:
Nail a slat to the north side of an upper window--the higher the better. Let it be 25 feet from the ground or more. Let it project 3 feet. Kear the end suspend a plumb-bob, and have it swing in a bucket of water. A lamp set in the window will render the upper part of the string visible. Place a small table or stand about 20 feet south of the plumb-bob, and on its south edge stick the small blade of a pocket knife; place the eye close to the blade, and move the stand so as to bring the blade, string, and polar star into line. Place the table so that the star shall be seen very near the slat in the window. Let this be done half an hour before the greatest elongation of the star. Within four or five minutes after the first alignment the star will have moved to the east or west of the string. Slip the table or the knife a little to one side, and align carefully as before. After a few alignments the star will move along the string--down, if the elongation is west; up, if east. On the first of June the eastern elongation occurs about half-past two in the morning, and as daylight comes on shortly after the observation is completed, I prefer that time of year. The time of meridian passage or of the elongation can be found in almost any work on surveying. Of course the observer should choose a calm night.
In the morning the transit can be ranged with the knife blade and string, and the proper angle turned off to the left, if the elongation is east; to the right, if west.
Instead of turning off the angle, as above described, I measure 200 or 300 feet northtward, in the direction of the string, and compute the offset in feet and inches, set a stake in the ground, and drive a tack in the usual way.
Suppose the distance is 250 feet and the angle 1° 40', then the offset will be 7,271 feet, or 7 feet 3¼ inches. A minute of arc at the distance of 250 feet is seven-eighths of an inch; and this is the most accurate way, for the vernier will not mark so small a space accurately.