Mid 20th century US Army issue Keuffel and Esser / Gurley surveyor's scope / transit level. Scope marked W. & L.E. Gurley, Troy, NY, USA - 431915. Base marked 8 THDS - K&E - 3 1/2 x 8.

"A transit level is an optical instrument, or a telescope, complete with a built-in spirit level that is mounted on a tripod. Transit levels are used mainly for surveying and building, but they can be used to determine the relative position of lines and objects as well. Transit levels are very precise. They are used to establish a reference line, but they are also used to provide readings of angles in precise measurements." (Source: Johnson Level)

"The Keuffel and Esser Co., also known as K&E, was an American drafting instrument and supplies company founded in 1867 by German immigrants Wilhelm J. D. Keuffel and Hermann Esser. It was the first U.S. company to specialize in these products. In 1876, K&E started selling surveying instruments. K&E was incorporated in 1889. K&E acquired instrument maker Young & Sons of Philadelphia in 1918 and made it a department of the firm, retaining the brand name for a time. In 1984, Rowley-Scher Reprographics, Inc., a company then based in Washington D.C., acquired K&E's reprographics businesses in Arlington, Fairfax, and Norfolk, all located in Virginia. Keuffel and Esser was acquired by AZON Corporation in 1987." (Source: Wikipedia)

"The Gurley enterprise was established in 1845, first as the partnership of Phelps & Gurley and in 1852 as W. & L. E. Gurley.  William Gurley and his younger brother Lewis E. were both engineering alumni of Rensselaer Polytechnic Institute, in Troy, NY, and brought to the business a hunger for technical innovation and unrivaled marketing skill.  Exposure at the Centennial Exposition in 1876 launched the company into international prominence from which it never fell.  The brothers built a factory in 1852 that operated in departments, each department turning out different components, which were then assembled.  This revolutionized the industry which, to that time, operated as small shops making, essentially, individual instruments.  Gurley was able to roughly halve the price of their instruments over those of their competition, while maintaining quality. Throughout the 19th century Gurley continued to expand its product line and gradually moved into others.  In 1885 Gurley began making hydrologic equipment, like current meters; in 1903 they opened a department of Weights & Measures; in 1905 they acquired Charles Wilder Thermometers and moved it to Troy; in 1908 they opened Department P, making mechanical, electrical, and scientific apparatus; in 1923 they launched a line of paper testing equipment; and in the 1950s moved into applications of optical encoder technology. Incorporated in 1900, Gurley responded to the worldwide demand for their products by opening the Seattle Factory Branch in 1909, to serve the Pacific Rim and Asia.  Gurley remained highly visible to the engineering and surveying professions by supplying instruments to major engineering projects and to expeditions, like Admiral Byrd's.  During World War II, Gurley distinguished itself by winning coveted Army-Navy E Awards for outstanding contribution to the war effort. Teledyne Corporation purchased W. & L. E. Gurley in 1968 and the company became Teledyne Gurley.  Production of surveying instruments ceased in 1980 in the face of stiff foreign competition and the technological shift away from optical instruments.  In 1993 Teledyne sold Gurley and the company became Gurley Precision Instruments, Inc." (Source: Gurley)