The Photographic and fine art journal . 1 subjected thefilms to inspection under the microscope. I then observed thatsome kinds were not only entirely free from reticulations, butthat the particles of iodide of silver were so nnnute as to requireconsiderable optical power to resolve them, At this point theidea occurred to me of ascertaining the relative capabilitiesof each sample of collodion in regard to its power of recording,pictorially, minntiffi of detail. It was accordingly resolved that pliotograjdis should be pro-duced of as small a size as possible, so as to bear inspection underthe l
The Photographic and fine art journal . 1 subjected thefilms to inspection under the microscope. I then observed thatsome kinds were not only entirely free from reticulations, butthat the particles of iodide of silver were so nnnute as to requireconsiderable optical power to resolve them, At this point theidea occurred to me of ascertaining the relative capabilitiesof each sample of collodion in regard to its power of recording,pictorially, minntiffi of detail. It was accordingly resolved that pliotograjdis should be pro-duced of as small a size as possible, so as to bear inspection underthe lower powers of a good conqionnd achromatic microscope;and as all things were arranged by the comnieneement of March,1854, the first pictures were then produced and exhibited 1osome friends at the house of Mr. Rosling. These pictures were also exhibited to the Society in the April ensuing, as was re-corded in the Societys journal at that period. The following diagram illustrates the general disposition ofthe various pieces of a is the source of light; i is a thick short-focus less to collectthe liglit of the lamp and throw it towards the picture, where,from the convergence of the rays, the light would form rathertoo small a spot ; the lens, c, is therefore interposedso as to spread the light out to cover completely the negatived. The negative, for convenience sake, being pressed againsta plate of glass by a spring; all in the plane at d. Now theend of all this arrangement is simply to give us a clearly illu-minated picture of about three inches in size, which we proceedto reduce to microscopic dimensions by the microscopic cameralens, which is lixed in a tube at e; e being about the place ofthe substage of the microscope. Our camera lens is, of course,of exceedingly short focus, for its ground glass or collodion filmsubstitute is to be placed at g, which is the usual place for theprincipal stage of the ordinary microscope. Wood is here sub-stituted for metal, because
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Keywords: ., bookcentury1800, bookdecade1850, bookidphotographic, bookyear1854
