. The American annual of photography. In the case of extremely rapid shutters the line, A B, may beso short, if the revolutions be only 60 per minute, that theangle, A C B, cannot be accurately measured. I give here, forexample, the result of a very rapid shutter. In this case thedifficulty is increased by the fact that, the lens being only aquarter plate one, the scale is very small. It will be seen thatthe silver ball gives but little more than a spot on the could only estimate from this that the exposure seemed to besomewhat shorter than y^-g- of a second ; by making a secondexposur
. The American annual of photography. In the case of extremely rapid shutters the line, A B, may beso short, if the revolutions be only 60 per minute, that theangle, A C B, cannot be accurately measured. I give here, forexample, the result of a very rapid shutter. In this case thedifficulty is increased by the fact that, the lens being only aquarter plate one, the scale is very small. It will be seen thatthe silver ball gives but little more than a spot on the could only estimate from this that the exposure seemed to besomewhat shorter than y^-g- of a second ; by making a secondexposure with the wheel revolving at 180 revolutions per second,I found it to be T-§-F second. W. K. Alvey A. Adee, Photo DOUBLES. Levy type Co., Phlla. ANP PHOTOGRAPHIC TIMES ALMANAC. 39 DEVELOPING AND FIXING GELATINE NEGATIVES. It is now pretty generally conceded that the gelatine dryplate, by progressive improvements, has reached a perfectionnearly or quite equaling wet collodion. Far excelling the lat-ter in sensitiveness, and in being always ready for exposure,the gelatine dry plate still lacks some advantages in manipulat-ing which the wet collodion has, inducing experimenters tocontinue their efforts to produce a dry collodion plate whichshall equal the gelatine in rapidity. As yet this consumma-tion has not been reached, though the patient seekers are stillstriving, and occasionally notify us (prematurely) of their suc-cess. The dense structure of gelatine in comparison with theporous texture of collodion opposes the penetration of thedeveloping and fixing baths, making them slow in action, andthe final elimination of the hypo still more tedious and unsat-isfactory. It is sca
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1892
