G. H. Crosby Indicator, Patent Model

This indicator was filed to the U.S. Patent Office with the application for patent no. 219149 issued to G. H. Crosby, September 2, 1879.

The model cannot be disassembled and the piston is stuck in the cylinder. It consists of a large drum with spiral spring and single record, but the linkage is different from the other Crosby indicators in the collection: a spring releases to move the drum back away from the pencil print.

The improvements claimed for this design are a jacket about the steam cylinder to prevent radiation or loss of heat from the cylinder; a method of supporting the cylinder and jacket so that each might expand freely when heated; the carrying of the rotary drum on a ...