Page "Shaped charge" Paragraph 7
from
Wikipedia
The Munroe effect is named after Charles E. Munroe, who discovered it in 1888.
A civilian chemist working at the U. S. Naval Torpedo Station at Newport, Rhode Island, he noticed that when a block of explosive guncotton with the manufacturer's name stamped into it was detonated next to a metal plate, the lettering was cut into the plate.
Conversely, if letters were raised in relief above the surface of the explosive, then the letters on the plate would also be raised above its surface.
In 1894, Munroe constructed the first crude shaped charge:
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