The SciencesOn the Cheapest form of Light.—From Studies at the Allegheny ObservatoryBy S. P. Langley, F. W. Very on March 29, 1902AdvertisementABOUT THE AUTHOR(S)Recent Articles by S. P. LangleyExperiments with the Langley AerodromeThe Fire Walk Ceremony in TahitiThe Laws of NatureRecent Articles by F. W. VeryWater-Vapor on Mars