. Behavior monographs. Animal behavior. 12 CORA D. REEVES d. Apparatus for Regulation of the Intensity and Distribution of Light. A plano-convex cylindrical lens (Yerkes 1903) 20 cm. long and 10 cm. wide, with a radius of curvature of cm., was divided crosswise into halves. One of these was fitted into the frame at the bottom of the lamphouse in each side (SL in figs. 2, 4). The Nemst lamps are placed at the principal foci of the lenses with the glowers parallel to and above the long axis of the lenses. In this position the cylin- drical lenses serve to parallelize the light rays in the d
. Behavior monographs. Animal behavior. 12 CORA D. REEVES d. Apparatus for Regulation of the Intensity and Distribution of Light. A plano-convex cylindrical lens (Yerkes 1903) 20 cm. long and 10 cm. wide, with a radius of curvature of cm., was divided crosswise into halves. One of these was fitted into the frame at the bottom of the lamphouse in each side (SL in figs. 2, 4). The Nemst lamps are placed at the principal foci of the lenses with the glowers parallel to and above the long axis of the lenses. In this position the cylin- drical lenses serve to parallelize the light rays in the direction indicated in figure 4. As the walls of the aquarium are black, the diverging rays which strike them at the sides of the stimulus plates (see fig. 5) are so little reflected as to be scarcely visible. But as the margins of these areas remain parallel they vary only in brightness not in shape. Their variation in brightness will be the same as the variation of the stimulus patches depending upon the slit-width. By this method no direct light from the glowers reaches the floor of the aquarium, and though the whole of each stimulus plate (S in fig. 2) is not illuminated, the patches of light on the two are exactly the same in shape and size. They are rectangular cm. by cm., and their edges are always sharp and straight across the plates. To regulate the light intensity a slit is used (figs. 2, 4, 5). The slit consists of two steel plates and a narrow steel frame which is the size of the inside cross-sec-. FiG. 5 Cross-section of one-half of lamphouse through Nemst glower along line uv in figure 1. A'^, Nemst glower. 0, slit opening. RF, ray filter in kit ki. SL, cylindrical lens. S, stimulus plate of opal ground glass. W, groove in which the frame for the slit slides in and out. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfec
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