Hydrographical surveying : a description of means and methods employed in constructing marine charts (1920)
Wharton, W. J. L. (William James Lloyd), 1843-1905, Field, Arthur Mostyn, 1855- · London : J. Murray · leaf 54
ion.Then, slightly loosening the screw clamping the arm, finallyadjust the latter, so that the object, as regarded through thehole in the mirror, is obscured by the white cardboard disc inthe centre of the ring. By turning the mirror so that the darkshade caused by the blind spot is thro^vn on to… … LOOKING-GLASS AS FITTED BY BLACKSMITH FOR HELIOSTAT. a. Sliding collar carrying arm m, revolving round s ; h, wooden ring, paintedblack, with cross-wires and white cardboard centre, sliding vertically by meansof rod through arm m ; c, iron frame to hold mirror, fitting into socket in topof standard…
Hydrographic surveying · Nautical charts
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