This "Convertible Level" is based on the patent (#1,234,520) for a combined level and transit granted on July 24, 1917, to Adolph Wissler (1866–1926), the St. Louis instrument maker who made many of the surveying instruments sold by Aloe. With the telescope in its standard position, it is a standard architect's level. With the telescope turned 90 degrees, it can be used to take vertical sights. The small horizontal circle is graduated to degrees, and read by vernier to 5 minutes. The level is provided with a metal trivet for setting up the instrument in places where the use of a tripod is difficult. The level is marked "A. S. Aloe Co. St. Louis 90607" and "PAT. 7-24-1917." New, it cost $75.
Ref: A.S. Aloe Co., Instruments and Supplies for Civil Engineers, Architects, Surveyors (St. Louis, about 1919).
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