The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Under-Exposure
Uranium
depth of the jig being adjusted to the height of the face above the shank or body in the case of the particular body-mould to be used. (In this particular instance the depth of the jig was • -049 in.) The back of the piece bearing the character is now filed away until the thickness of the piece corresponds to the depth of the jig; and the character is next soldered to a thick strip of flat brass, a highly fusible solder being used. Before electrotyping the character as it stands soldered to the flat plate it may be necessary to file one side or more so as to make an even slope up from the base plate to the face of the character. The author, continuing his subject, said: " For this purpose I cut a file such as I show you ; a flat file, all ' safe ' excepting one edge which makes an angle of 960 with one of the flat faces ; and con-sequently 840 with the other flat face ; this file being used to trim up the character on four sides (if necessary) until the face is just short of being cut into. We thus get a ' photographic punch,' which, for casting purposes, is equal to the ordinary steel punch. Before electrotyping on this punch, it saves much time to rule fiducial lines having proper relation to the mould in which the type is to be cast. These can be ruled with simple bridge-like gauges from the margins of the character. When the elec-trotype is made, and backed up in the way which is usual for electrotyed matrices, nothing remains to be done but to saw off and file to the fiducial lines as reproduced on the electrotype - the depth of the matrix having been determined by the jig already mentioned."
Under-Exposure is when the duration of exposure of the sensitive surface is not sufficiently prolonged to impress the details of the object on the sensitive surface. Its effects are thinness of negative, without detail. When under-exposure is suspected, the only thing to do is to reduce the bromide in the developer, and coax the image out with very slow and careful development. To increase density, intensification may be re-sorted to, but nothing can improve the lack of detail.
Uranium (Ger., Uran;Yx.t Urane; Ital., Uranid). U = 240. A rare metal never found in a pure state, but as an impure oxide, called pitchblende. It is used in the form of nitrates for preparing a printing-out paper, and for intensification.
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