Report of comparative tests of roundels from an ophthalmologist's standpoint (1904)
Black, Nelson Miles, author · [Bethlehem, Pa.?] : [publisher not identified] · leaf 10
resent the percentage of distance at which the illumination became equal: RED ROUNDELS. GREEN ROUNDELS. Corning, 100 per cent. Corning, 100 per cent. Sneath, 87.2 per cent, (flashed Sneath, 92.8 per cent. glass ) . Baird, 69.4 per cent. Kopp, 75.7 per cent. Macbeth, 67 per cent. Baird, 54.7 per… … Fig 3- condensing lens of latest improved pattern, burning headlight oil which flashed at 110 degrees F., and having plane of flame parallel to plane of condensing lens, was used. This was placed between double tracks on a support opposite a mile-post; each roundel was placed before it in turn.…
Lighting · Color · Railroads
Internet Archive · U.S. National Library of Medicine · Public domain (published before 1931). Free to use for anything.
