William Gurley (1821–1887) studied civil engineering at Rensselaer
Polytechnic Institute, worked for Oscar Hanks, a surveying instrument maker in
Troy, New York, and then went into partnership with Jonas H. Phelps, another
local instrument maker. Lewis Ephraim Gurley (1826–1897) worked for Phelps
& Gurley, earned a B.A. from Union College, and then rejoined the firm. The Gurley brothers took over the firm in 1852, began trading as W. & L. E. Gurley, and were soon the largest manufacturer of engineering and surveying instruments in the United States. Several factors contributed to their success. They established a factory rather than a craft workshop, practiced a strict division of labor, hired workers who were relatively unskilled, advertised
widely, and offered instruments at competitive prices. Their Manual of the
Principal Instruments Used in American Engineering and Surveying, published from 1855 to 1921, was a catalog of their instruments and an intelligent explanation of how they were to be used.
The design of Gurley instruments remained remarkably stable for many years, making it difficult to determine the date of a particular instrument. But there
are some important clues. Since the signatures on the early Gurley instruments
were cut by hand, the letters have V-shaped trenches, and their lines are of
varying width. By contrast, the signatures on Gurley instruments made after 1876 were done with an engraving machine, and thus have lines with vertical walls and uniform width. The Gurleys introduced serial numbers in 1908, with the first digits indicating the year of manufacture, and the latter digits indicating
production rate. Thus, transit #9296 was the 296th Gurley instrument made in
1909. W. & L. E. Gurley was incorporated in 1900, with all the stock held by the family. Teledyne purchased the firm in 1968, began trading as
Teledyne-Gurley, and phased out the production of surveying instruments soon
William H. Skerritt, "W. & L. E. Gurley’s Engraving
Machine," Rittenhouse 11 (1997): 97–100.
Skerritt, Catalog of the Charles E. Smart Collection of Antique Surveying Instruments (Troy, N.Y., 1996).