Means for Determining the Relative Times of Development of Photographic Plates or Films for Different Temperatures.

摘要

12,120. Watkins, A. May 22. [Addition to 22,456/07]. Logarithmic calculators. -Relates to modifications of the apparatus described in the parent Specification, for determining the relative times of development of photographic plates or films for different temperatures, and comprising two relatively movable slides, one bearing a temperature scale and the other a logarithmic scale representing time values, and in particular to such apparatus in which a thermometer is used as t h e temperature s c a l e. In the present modification, the thermometer does not bear a temperature scale, and the relative times of development for different temperatures are directly indicated by the expansion of a fluid. A thermometer has a single mark representing a standard temperature (say 60‹ F). The relatively movable logarithmic scale determined for a medium plate is positioned so that the correct time of development at 60‹ F. is indicated by this mark. The level of the fluid in the tube then directly indicates the time of development. The logarithmic scale, mounted on an endless band passing over two rollers b, is enclosed in a casing b1 with a removable cap c, being thereby adjustable for other classes of plates. In a second modification, the logarithmic scale is fixed, in which case a certain time of development correct for a plate and a fixed dilution of a stated developer is determined in relation to the height of the fluid at a standard temperature. This particular combination serves for certain other plates with other specific dilutions of the same developer. The logarithmic scales used are prepared or calculated in the manner described in the above-mentioned Specification.