An account of the history of the coherer principle would not be
complete without a reference to an interesting reminiscence of
early observations recently put on record by the discoverer of the
microphone. At each stage of his observations of electrical cohesion
between metals the author was confronted by a reference to some earlier
observations of Prof. Hughes, and he felt sure that during the work
on the microphone many or all of the phenomena he was then observing
must have been previously encountered by Prof. Hughes. No full account
was at that time available, however, but now it is clear that the
observations were made (like some of Edison’s on what he called etheric
force, and like the very remarkable still earlier ones of Joseph Henry)
before the time of Hertz, when the existence of electric waves able to
excite sparks or perform other energetic acts was unlooked for and not
clearly understood.
Nevertheless, at this early period it is clear that Prof. Hughes
observed, though he did not follow up the observation, not only the
occurrence of electric waves or impulses in space, but also the coherer
method of detecting them; in fact, that he unwittingly made the
earliest experiments on wireless telegraphy by this plan.
The simplest way is to quote Prof. Hughes’s letter to Mr. J. J. Fahie
from _The Electrician_, May 5, 1899, p. 40, beginning with Mr. Fahie’s
letter as an introduction:--
_Extract from recent letter from Mr. J. J. Fahie to
Prof. Hughes._
“DEAR PROF. HUGHES: I have now in the press
a history of Wireless Telegraphy from 1838 to 1899,
and in writing to Sir William Crookes for information
he tells me that many years ago he saw some
experiments of yours with the microphone, in which
you signalled from one part of a house to another
without connecting wires, and he desires me to refer
to you for particulars. I think, with Sir William,
that it is a pity you have not hitherto published
your results, and I sincerely hope you will now do
so. If also you would kindly favour me with a short
account, I could find room for it in my book, which
is now in the printer’s hands.--Sincerely yours,