TESLA, Nikola (1856 - 1943). Autograph letter signed ("N. Tesla") to Robert Underwood Johnson, New York, 26 January 1894.

Two pages, 138 x 215mm., on Gerlach Hotel letterhead (a few light scuff marks on the verso, possibly from prior mounting).

Shortly after taking the first photograph ever illuminated by phosphorescent light, Tesla notes "defects" and requests more experiments before they are published. Writing to his friend Johnson, editor of The Century Magazine, Tesla is firm in the belief "that we can attain excellent photos" and that the "ingenious scheme of combining with the phosphorescent lamp[?] a flash will no doubt succeed". However, he admits "some defects in the method we have employed last time" and wishes to arrange for other trials and "a few more experiments before we come to a definite result, such as would be a credit to your magazine and to your article." Tesla developed the first practical phosphorescent lamp, and would take the first photograph to be illuminated by phosphorescence—an image of Tesla himself holding the bulb in a rather dimly-lit room—in the weeks preceding this letter. Provenance: Charles Hamilton, 3 April 1975, lot 287.