ALUMINUM GEOLOGISTS COMPASS U.S. FOREST SERVICE STANDARD by W. & L.E. GURLEY
06-047. 119. American, 1st quarter 20th century, signed on the compass face "W. & L.E. GURLEY, TROY, N.Y., U.S.A." and described in their catalogs as follows: "This instrument has proved admirably adapted for topographical work, and has been adopted by the U.S. Forest Service for use of field men in making forest surveys and maps. It is made of aluminum to secure lightness in weight and has a needle two and five eights inches long enclosed with its compass circle in a circular box set on a plate four inches square. The edges of this base are beveled and graduated two for a tangent scale and two to inch scales. One of these latter is graduated to eights, each of which represents ten chains, and the other is decimal. The compass circle is made movable, and by a vernier attached to it on the inside the magnetic declination may be set off to five minutes. On the under side of the plate is a township plat. On the south side of the compass face is an arc of 180 degrees figures on each side of the 0 line from 0 to 90. A weighted pendulum hung from the center pin indicates by its pointer on this arc, the angle of the slope, when the compass is placed so that it rests on its south edge. On the outside of the box containing the compass circle is a movable circle, beveled and graduated on its upper edge and figured form 0 to 90, and having at each quadrant a slit for sighting. Two tall folding sights are attached to the edge of the circular box, and two small levels are placed at right angles with each other upon the base. The compass is supported on a simple ball spindle and socket, with staff mountings, and is usually carried in a leather pouch with shoulder and belt straps." This compass and its leather case are both in good overall condition.
