This pocket notebook was used by Edison. The only dated entry is for April 12, 1889, and concerns incandescent and arc lamp designs. Preceding that entry is a series of numbered notes on phonograph cylinder experiments. The book was also used from the back forward for notes on chemical reagents and a list of elements and densities. The pages are unnumbered. Approximately 50 pages have been used.

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Courtesy of Thomas Edison National Historical Park.