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Caveats are preliminary patent applications. Until 1910 the U.S. Patent Office permitted an inventor to file an official notice regarding work in progress. Caveats were valid for one year and could be renewed from year to year upon payment of a fee. If another inventor subsequently filed an application for a similar invention, the first inventor was so notified.
The caveats relate to a variety of subjects, including the phonograph, motion pictures, ore milling, and fluorescent lamps. There are fourteen files for the period 1887-1896, with Edison case numbers 110-123. These are arranged in case-number order. In addition, there are eight caveat drafts covering the period 1887-1890 that lack case numbers. These appear in chronological order following the numbered files. For most of the numbered caveats, there are draft notes and drawings in Edison's hand and a typed copy, which was retained by attorney Richard N. Dyer. Since there are often substantive differences between the two versions, both have been included. However, the blueprint drawings retained by Dyer have not been selected except for those accompanying the three caveats lacking a draft by Edison.
The caveats in the Patent Series bear a close relationship to the notes and drawings in the Notebook Series, many of which carry inscriptions indicating that they were used in the preparation of caveats or patent applications. Courtesy of Thomas Edison National Historical Park.