Screw Propellor, Patent Model

This is the patent model of John MacHaffie's screw propeller, which he called "the citropeller adopted to aquatic propulsion."

John MacHaffie, a British citizen living in Schenectady, New York, received a patent in 1892 for a new propeller shaft arrangement, wherein the speed and direction of a propeller could be adjusted by moving the drive shaft in and out. The adjustable shaft would engage a clutch in the propeller bearing, causing the propeller to spin forward, stop, or reverse without changing the speed or direction of the shaft or the vessel's engine. MacHaffie's specification also outlined a way to use his invention for steering as well, but that possibility is not reflected in the patent model. MacHaffie called his device a "citropeller," perhaps intending to mean a propeller tilted sideways.

MacHaffie's citropeller was also covered by British patent 12,361, August 7, 1890.

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