The Science record; a compendium of scientific progress and discovery . amera obscura, of which we give two forms. Fig. 8 is anarrangement adapted to taking views from windows orother fixed positions. It is a rectangular wooden box,formed of two parts, which slide in and out. The lumi-nous rays pass into the box by a double convex lens se-cured in place as represented in section 2, and form animage on the opposite side, which is at the focal distanceof the lens. But the rays are reflected from a glass mir-ror inclined at an angle of 450 and form an image on apiece of ground glass inserted abov
The Science record; a compendium of scientific progress and discovery . amera obscura, of which we give two forms. Fig. 8 is anarrangement adapted to taking views from windows orother fixed positions. It is a rectangular wooden box,formed of two parts, which slide in and out. The lumi-nous rays pass into the box by a double convex lens se-cured in place as represented in section 2, and form animage on the opposite side, which is at the focal distanceof the lens. But the rays are reflected from a glass mir-ror inclined at an angle of 450 and form an image on apiece of ground glass inserted above. When a piece oftracing-paper is laid on this screen, a drawing of the imageis easily made. The wooden door shown serves to cut offextraneous light. The parts of the box slide one withinthe other, like the joints of a telescope, so that by elon-gating it more or less, the reflected image may be made tofall exactly on the screen, at whatever distance the objectmay be situated. THE PORTABLE FIELD CAMERA OBSCURA. Fig. 9 is another arrangement of the camera obscura. in. AIDS TO DRAWING.—FIG. Q.—THE FIELD CAMERA. MISCELLANEOUS. 575 portable form, so as to be carried on sketching box or lantern portion shown in detail in Fig. 10 con-sists in front and rear pieces of wood or tin, connected atthe sides by cloth or paper, folded like the bellows of anaccordeon. In the front side is thelens, placed in a little telescope of tin,which easily slides in and out and in-side of the back, and at its lower edgeis hinged a small mirror, which, whenthe box is extended, falls forward un-til it strikes against a stop within thefront side, which maintains it at anangle of 450. Any convenient ar-rangement may be added to hold thebox extended. When the latter isclosed, the mirror folds against theback, the lens telescope slides in, andthe front and rear sides come togeth-er, making a bundle little larger thana good-sized pocketbook. At eachcorner is a socket to receive the endsof bent i
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Keywords: ., bookcentury1800, bookdecade1870, booksubje, booksubjecttechnology
