Snelling, Henry Hunt, 1816-1897 · [New York : W.B. Smith] · leaf 274
it may be seen through the glass g. The box being carefully closed, the spirit lamp is to be lighted and placed under the cup containing the mercury. The heat is to be applied until the thermometer, the bulb of which is covered with the mercury, indicates a temperature of 60° centigrade, (140Q… … 38 After a few minutes, the image of natureimpressed, but till now invisible, on theplate, begins to appear ; the operator as-sures himself of the progress of this develop-ment by examining the picture through theglass, g, by a taper, taking care that therays do not fall too strongly on the…
Photography · Art and photography
Internet Archive · Smithsonian Libraries · Public Domain Mark 1.0. Free to use for anything.
