The manuals published by W. & L.E. Gurley, one of America s leading producers of mathematical and scientific instruments, have been used by generations of engineers and surveyors. In this manual Gurley describes all of its various instruments: how they are calibrated, used and maintained, and includes a catalog of its complete instrument line. This 1874 edition is especially valuable since it is one of the earliest and is rarely found. With an introduction by David C. Garcelon.