[LB063011], Letter from Thomas Alva Edison to Frank Loney Perry, February 5th, 1898
https://edisondigital.rutgers.edu/document/LB063011
Transcription
Feby 5/98 Frank L Perry Esq Dear Sir — The most curious thing in the electrical line that I know of is the instantaneous control of mechanism at a distance over a wire by currents extremely weak when passed through a cylinder of compressed Calcium Phosphate upon which the electrodes rest. Yours Thomas A Edison