This compass has a 4 inch needle (the same "as is furnished with Gurley Precise Transits"), needle release, two folding sights, two levels on the face, and a jacob staff mounting. Gurley introduced this form in the 1920s,
describing it as "an excellent and portable instrument for running lines through woods." This example belonged to the University of Missouri at Columbia. New, it cost $35.
Ref: W. & L. E. Gurley, The Gurley Line (Troy, N.Y., 1929), p. 305.