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. New, the level cost $75.
Ref: A. S. Aloe Co., Instruments and Supplies for Civil Engineers, Architects, Surveyors (St.
Louis, about 1919).