[LB040455], Letter from Thomas Alva Edison to Dyer and Seely, Henry W Seely, May 9th, 1890
https://edisondigital.rutgers.edu/document/LB040455
Transcription
May 9, 1890 H.W. Seely, Esq., Messrs. Dyer & Seely, #36 Wall St., New York Dear Sir:- I beg to acknowledge receipt of your letter under date 6th instant, in regard to an application of mine for a process of duplicating phonograms by depositing through the means of an electric arc or incandescence in a vacuum to make a thin film of metal on the wax phonogram, and in reply I would say that this process is a perfect success and we have deposited hundred of cylinders. In regard to heat, there is, of course, a certain amount, but as the film deposited is one two-hundred-thousandths of an inch thick, and it takes three hours to make the deposition, the amount of heat given off in a minute over, say 1/8 of an inch square, is exceedingly small. Yours very truly, Thos A. Edison