. The Adolfo Stahl lectures in astronomy, delivered in San Francisco, California, in 1916-17 and 1917-18, under the auspices of the Astronomical Society of the Pacific. %. ^??, ?.; PLATE XX. Copernicus. Drawing by Professor E. L. Weinek. From the negative taken at the Lick Observatory on July 2S, 1891. ISi 49! 16^ P. S. T. The Moon 93 yellow one and only faintly visible in the violet one. ProfessorWood took two specimens of volcanic tufa of about the samecolor, one of which photographed light and the other dark inrays of ultraviolet light. Placing a small chip from the dark-specimen upon the l
. The Adolfo Stahl lectures in astronomy, delivered in San Francisco, California, in 1916-17 and 1917-18, under the auspices of the Astronomical Society of the Pacific. %. ^??, ?.; PLATE XX. Copernicus. Drawing by Professor E. L. Weinek. From the negative taken at the Lick Observatory on July 2S, 1891. ISi 49! 16^ P. S. T. The Moon 93 yellow one and only faintly visible in the violet one. ProfessorWood took two specimens of volcanic tufa of about the samecolor, one of which photographed light and the other dark inrays of ultraviolet light. Placing a small chip from the dark-specimen upon the light one he secured effects exactly repro-ducing those shown by the Aristarchus spot. Analysis thenshowed that the dark cliip contained iron and traces of photographs of many rock specimens havingiron stains failed to give these effects, but by taking the speci-men of tufa which had photographed light in the ultravioletpicture and forming on a spot on its center a very thin depositof sulphur—so thin as to be invisible to the eye—he obtainedphotographs showing the spot quite black in the ultraviolet,gray in the vic^let and invisible in
Size: 1262px × 1979px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectastronomy, bookyear19
