This key shows the unique Lyman patent design with the lever suspended by a "Y" shaped piece of spring steel.
This key was made by A.B. Lyman of Cleveland, Ohio
A.B. Lyman made keys from 1876 to 1880.
This particular model was called the A.B. Lyman Steel Lever Key. Lyman advertised it as
"The Most Perfect Key in the World."
It certainly has a unique construction among telegraph keys, with two metal straps
meeting on the lever and acting as the spring.It is remotely reminiscent of the mechanism on Steiner keys.