﻿and Vision under Water. 161 



having a working angle of 180°. One of these is reproduced 

 in PL III. fig. 2, and represents the appearance of a circle of men 

 standing around the edge of a small pond, to a fish stationed 

 at the centre. The appearance of the buildings, telegraph- 

 poles, and small trees is also shown. 



The water camera was then modified so that it could be 

 pointed in a horizontal direction. The lens was dispensed 

 with and a pin-hole substituted, since it was found that as 

 good, if not better, definition could be obtained in this way. 

 The hole was made in the opaque film on the back of a piece 

 of modern mirror-glass, which was cemented, glass side out, 

 over a hole in the end of a water-tight box (fig. 1, lower 

 diagram). The plate was inserted in a dark room, and the 

 whole filled full of water, after which the cover was closed, 

 and a little additional water added through a small hole to 

 displace the enclosed air. The hole was then closed with a 

 stopper and the exposure made as desired. It will be seen 

 that the views obtained with the apparatus in the horizontal 

 position, represent things as seen by a fish looking out through 

 the glass sides of an aquarium. The cone of light entering 

 the fish's eye has an aperture of about 96°, but the rays 

 within it came originally from a cone of 180°. Very 

 curious pictures were obtained with this apparatus. It will 

 photograph all three sides and the complete ceiling and floor 

 of a room, or when placed at a point where two streets cross 

 at a right angle, will give a view looking down any three 

 streets, the view including the ground quite up to the base 

 of the tripod, and the sky from the horizon to the zenith. 

 Suspended from a balloon it would photograph the entire 

 surface of the earth out to the horizon in all directions. 



Some very curious pictures were obtained with the apparatus 

 in this form. A straight row of nine men, standing side by 

 side in a garden path, was photographed with the camera 

 standing not more than 18 inches in front of the central 

 figure. The straight path appears as if bent into a semicircle, 

 and the end figures appear distorted, as if seen by reflexion in 

 a cylindrical mirror. This view (tig. 3, PL III.) gives us a good 

 idea of how the visitors at an aquarium appear to the fishes. 

 Fig. 4 is a view taken at the intersection of two narrow streets, 

 and shows Monument Street, looking .wxst, with the dome of 

 the physical laboratory, and Eutaw Street looking north and 

 south; the foreground is recorded up to the base of the 

 camera's tripod, and the sky to the zenith, while an overhead 

 wire appears bent into an arc. 



Phil. Mag. te. 6. Vol. 12. No. 68. Aug. 1906. M 



