[The following note covers all the undated notes and drawings, ca. 1887-1898.]
Undated notes and drawings, prior to their reorganization, were generally filed in the Document File under an attributed year. Undated material that was probably generated within the year of attribution, along with other items that present no compelling evidence of being misfiled, are arranged according to the attributed year. Within each attributed year, documents by Edison and his closest associates and those items with the clearest experimental context appear first. Those documents for which no specific year can be reasonably conjectured appear at the end of the series.