Typed letter signed N. Tesla. With date and return address ("46 East Houston St., New York") neatly inked in Tesla's miniscule script in lower left. 18x17 cm (7x6¾"), matted and framed with a portrait of Tesla. Overall 33x47.5 cm (13x18¾").

Written in the year Tesla harnessed the power of Niagara Falls, this letter apparently relates to Tesla’s recent demonstration of his new vacuum tube lighting. The correspondent was a photographer who regretted being unable to attend and requested a further opportunity to photograph the apparatus at work – Tesla here giving his consent in stating: “I shall prepare the apparatus for taking another photograph Friday or Saturday at your pleasure.” The apparatus in question was a system of lighting by vacuum tubes, capable of producing a wide range of candle-power to practically any desired intensity. Tesla is reported to have stated that “photographs obtained by the light of such powerful tubes show an amount of detail which no picture taken by the sun or flash light is capable of disclosing.” It was at this earlier missed demonstration that the famous picture of Tesla sitting in front of a giant spiral coil was taken.