_To the Editor of the Scientific American:_
In your issue of June 19, 1880, I notice an illustration of an
electro-magnetic ore separator invented by Mr. Edison, and patented
June 1, 1880.
A device absolutely identical with this has been in use for the past
ten or fifteen years at the emery works at Chester, Hampden county,
Mass. I there saw it in use myself in November, 1876, and was
informed, I think by Mr. Ames, that it was not patented, and that no
valid patent could be granted upon it by reason of its long continued
public use.
My uncle, John S. Williams, of this city, president of the Ore Knob
Copper Company, had heard of the machine, and sent me to Chester with
a view to purchasing the right to use it at the Ore Knob Copper Works,
in Ashe county, North Carolina. On my return to Baltimore I had the
magnets constructed by Watts & Co., electricians, on November 24,
1876, for a large machine, similar to the one at Chester, which
machine was completed about December 10, 1876, and practically tested
at No. 52 Commerce St., Baltimore. It was sent to the Ore Knob Mine
about Christmas, 1876, to be used in separating magnetic oxide of iron
from the copper ore, and, for aught I know to the contrary, is in use
there yet. This is a striking instance of how history repeats itself
in inventions. Mr. Edison is doubtless an original inventor of the
device, but he most certainly is not the first inventor.