A manual of photographic chemistry, theoretical and practical . and the compound imageis perceived in the same place. 356 BINOCULAR PHOTOGRAPHY. If, instead of two similar objects as wafers, the right andleft perspective views of an object, such as the follow-ing of an hollow hexagonal cone, are viewed in a simi-lar manner a sensation of depth and elevation is obtained assoon as the images coalesce, the different parts of the coneappear at different distances from the observer, and what ismore singular the appearances are reversed bj the two modesof causing the pictures to coalesce. The diagra
A manual of photographic chemistry, theoretical and practical . and the compound imageis perceived in the same place. 356 BINOCULAR PHOTOGRAPHY. If, instead of two similar objects as wafers, the right andleft perspective views of an object, such as the follow-ing of an hollow hexagonal cone, are viewed in a simi-lar manner a sensation of depth and elevation is obtained assoon as the images coalesce, the different parts of the coneappear at different distances from the observer, and what ismore singular the appearances are reversed bj the two modesof causing the pictures to coalesce. The diagram. Fig. 51, viewed by focusing the eye for aa distance, or by the stereoscope, represents a cone, withthe small hexagon distant; but by squinting, the small endis made to stand ont towards the observer. As the formeris always the way of viewing objects by the stereoscope, it isonly necessary here to explain how the sensation of depth anddistance is produced by distant focusing, or viewing each halfwith the eye of the same side, and for the sake of simplicity. Fig. 53. only four points in each figure, A, C, D, B, and A, C, D, B,need be taken for the purpose of illustrating the mode in whichthe eye has to unite every corresponding pair of points inturn. In the diagram. Fig. 52, these letters represent the samepoints of the hexagons, as in Fig. 51. The points A and A, which correspond in the two largerhexagons, are united when the right optic axis R ^ is directedto A, and the left L A to A ; but the resulting single pointappears to be at E, where these axes meet; so, in like manner,B and £ unite, and form one point apparently, at F. Thepoints C C of the smaller hexagons being more distant fromeach other than A from A, or B from B, can only be unitedby a more distant prolongation of the optic axes L C and RC to the point of union G, which thus appears to be the posi-tion of these points of the smaller hexagons, and so with re-gard to D and D; and as these points are merely taken a
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Keywords: ., bookcentury1800, bookdecade1880, bookidma, booksubjectphotography
