thomas edison > a lifetime of invention : early life
thomas edison > early life : menlo park, 1878-1879


"A Laboratory - The Idea," Menlo Park Reminiscences (by Francis Jehl)

Nobody of that day had ever heard of such a thing as a professional laboratory in which experiments were carried on toward practical ends.  The experiments of the research laboratories of the scientists were all made to add to the sum of human knowledge, but the practical application of that knowledge was for other hands.  Edison in boldly launching out as an inventor was unique.  Whatever he did was questioned severely by the savants of that day.  Some of what came out of the laboratory in Menlo Park, NJ, includes the carbon telephone transmitter, that made telephony an art for common use; the phonograph, that could reproduce the human voice; the magnetic ore separator; the high efficiency dynamo electric generator; the incandescent lamp; electrical conducting systems for electric light and power distribution; apparatus related to the development and implementation of the concept of the central station, first exemplified by the Pearl Street Station of New York City; conception and construction of an electric railway.

The Electric Pen

While at his Newark factory Edison invented the electric pen, a device widely used in professional offices at the time.  Francis Jehl, one of Edison’s early assistants, used an electric pen at his job prior to working for Edison at Menlo Park, New Jersey in 1878.  “I knew [Edison] as a caller at the law firm office on Wall Street where I was employed as an office boy.  One of my duties was to operate the electric pen, a device we had to make many copies of a single letter, and since it had been invented by Mr. Edison I wanted to seek and know the maker.”

Edison’s electric pen was used almost universally in business and professional offices during the late 1870s and early 1880s.  In operating the pen, the user got his current from a Bunsen battery consisting of two glass jars, capped at the top and controlled by a plunger with which he lowered the plates into the acid solution or drew them up when the pen was not in use.  Thus the life of the battery was prolonged.

The pen had a needlelike point which darted in and out of the writing end so rapidly that the eye could hardly detect it.  This was operated by a minature electric motor small enough to be attached to the upper end of the pen.  The shaft containing the needle was given its motion by cams on the rotating engine shaft so that when the current was turned on, and the user wrote with the pen, holding it in a vertical position, it made innumerable tiny punctures on the sheet of paper, tracing the words that comprised the letter.

After a master copy of the stencil had thus been made, the user took it to the press, where it had to be spanned in a frame before the copies could be made.  A plain sheet of paper was placed on the press, the stencil was laid on top and an ink roller passed over it.  The impressions of the handwriting was marked on the under sheet by the ink through the holes made by the needle.  It was said that 5,000 copies could be made from a single stencil.

Its widespread use is indicated by the fact that, within three years after Edison brought it out, it could be found in the government offices in Washington, D.C., in city and state offices, and in such far-away lands as Australia, New Zealand, China, Brazil, Russia, and elsewhere.

Sources: Menlo Park Reminiscences, by Francis Jehl.

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