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MICRO-PHOTOGRAPHY AND PROJECTION APPARATUS 335
Should the image as viewed on the screen appear at all distorted, it may be taken as a clear indication that the prisms P and P1 are not properly adjusted.
The clips to be seen on the tube B (fig. 145) are for the purpose of holding any light filters which may be required. If desired, a shutter can be attached to the carrier S2 when the apparatus is used for obtaining photographs. If may be as well to add that an e3Te -piece as well as objective is used in this instrument when taking a photograph ; the eye-piece is attached by means of a fitting which is put in the sleeve at the end of the camera. The final focussing is done by means of the lower attachment beneath the camera (fig. 144).
The lens L, as shown in figs. 144 and 145, is for use when it is desired to work with low magnifications ; for this purpose it is also necessary to raise the lamp, and move it as near as possible to the stand. The object is illuminated by the light reflected from the glass plate, which is attached to the slider S (fig. 145) for this purpose.
Lantern Slides. — The permanent records obtained by means of microphotography can be made of much more extended use by preparing lantern slides from the photographs. The lantern slides should, if properly prepared, show much better gradations than ordinary prints obtained from the same negative. To prepare the lantern slide, the sensitized plate should be placed in the printing-frame with its film side to the film side of the negative. This of course should be done in the dark room. The exposure is best carried out by artificial light, the plate being placed at a definite distance from the light and so arranged that the fight strikes it as nearly vertically as possible. The development and fixing of lantern slides is carried out in the same manner as that of ordinary plates, but it is well to remember that the success depends upon the fight transmitted by the slides, so it is better to avoid developing too far.