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THE ADVANCE OF PHOTOGRAPHY
interior of the ear (fig. 98) consists of three parts : 1st, the ear-funnel A ; 2nd, the illuminating apparatus B ; 3rd, the photographic apparatus D, with the lenses C. These parts are placed together, as may be seen in the accompanying diagram. The instrument is fastened by a ball and socket joint to a suitable stand, in order to give it the proper direction, according to the position of the sun. The ear-funnel A is a conical tube about 1J inches in length, to push aside the small hairs which interrupt the view ; it is made of vulcanized india-rubber. The illuminating apparatus B, which is easily closed by a cover at a d, consists of two metal tubes, soldered tof gether at a right
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angle at b c, of which one is provided with parallel, the other with curved sides. At the place where the two tubes unite is a perforated metallic mirror (eg f), inclined at an angle of 45°.
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Fit'. 98.
The photographic apparatus consists of a double objective C and a small camera, two inches deep. The ground-glass screen X, and the dark slide Y, are fitted in a frame D, easily moved. A plano-convex lens is placed at h, between the objective and the illuminating apparatus. According to the position of the sun, bright cloud, or any other source of light, the apparatus B can be moved by turning round on its axis ; so that, in conjunction with the joint of the stand, the apparatus can be turned easily and steadily in all directions.
The rays which penetrate into the tube B are thrown by the perforated plane mirror e / through A on the drum of the ear. Reflected thence, they pass at g the perforated plane mirror, and the image of the drum of the ear is