. Lighthouse construction and illumination; . Fig. 70. Lighthouses, for whom it was constructed, in order to furtherthe realising of what Mr. Thomas Stevenson had ingeniouslysuggested about twelve years previously. During the progTess of this instrument the ideaoccurred to the author of separating the zones, and also ofdividing them into segments, like the ordinary reflecting 94 LIGHTHOUSE ILLUMINATION. zones of a dioptric light; by this mecans it became practi-cable to increase considerably the radius of the mirror, andthereby to render it applicable to the largest sea light, with-out overste
. Lighthouse construction and illumination; . Fig. 70. Lighthouses, for whom it was constructed, in order to furtherthe realising of what Mr. Thomas Stevenson had ingeniouslysuggested about twelve years previously. During the progTess of this instrument the ideaoccurred to the author of separating the zones, and also ofdividing them into segments, like the ordinary reflecting 94 LIGHTHOUSE ILLUMINATION. zones of a dioptric light; by this mecans it became practi-cable to increase considerably the radius of the mirror, andthereby to render it applicable to the largest sea light, with-out overstepping the limits of the angular breadths of thezones, and yet without being compelled to resort to glass ofhigh refractive power. ^ There can be no doubt of the advantage of these improve-ments, and it is without any intention of derogating fromMy. Chances merit in the matter that it is added that myfirst idea was also to generate the prisms round a verticalaxis. But the flint-glass which was necessary for so smalla mirror could not be obtai
Size: 1461px × 1710px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookpublisherlondo, bookyear1881
