C. L. Berger & Sons Engineer's Transit No. 1c, c. 1930s

An engineer's transit by C. L. Berger & Sons, Inc. of Boston, Massachusetts, Model No. 1c, serial number 34001, made in the 1930s. The maker described the model as intended "for work of a high class... bridge building, water works, and for city and land surveying", built for professionals requiring accuracy and fine construction.

The horizontal circle, 6¼ inches in diameter, is solid silver, with two opposite solid silver verniers set at 35 degrees to the line of sight, permitting readings to 30 seconds of arc. The vertical circle is likewise graduated on solid silver. The 11½-inch telescope gives 24× magnification, with the focusing knob placed at the top for smooth operation; the scope focuses accurately and the lenses are clear, giving a sharp view of the cross-wires.

Construction is in high-quality bronze bell-metal alloys with silver graduations, brass, an iron magnetic needle, glass, and mahogany for the base and case. The instrument stands 14½ inches high. A similar model is exhibited in the Physical Sciences Collection at the Smithsonian's National Museum of American History, Washington, D.C.