STAMPING.

The stamping is done by means of presses, and is a very rapid and

complete operation.

The operator takes a piece of the sheet copper, places it on the

press, the lever descends, there is a sharp crunching, bursting sound,

and in a time shorter than it has taken to describe, the letter is

made, sharp and perfect in every way.

Scientific American Supplement, No. 841, February 13, 1892 · 第 38 / 62 题