[LB056211], Letter from Thomas Alva Edison to John T Donovan, March 30th, 1892
https://edisondigital.rutgers.edu/document/LB056211
Transcription
March 30, 1892. Mr. John T. Donovan, No. 56 Greenwood Street, Springfield, Mass.. Dear Sir:- Your letter of 25th instant, in regard to filaments for incandescent lamps, is before me. Your base facts are not correct. There is not the slightest desire for a lamp filament to [illegible] in the air. A platinum lamp giving sixteen candles will, when the vacuum is broken, give less than one candle by reason of the loss of heat by convection-currants. Again, you are mistaken about the amount of energy it requires to bring different stances to incandescence. The energy is proportioned to the radiating surface and is independent of the material. Yours very truly, Thomas A. Edison