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1908-9.] A Special Form of Photographic Camera. 
part of the scale adjacent to it at the time require to be shown in each of 
the records. In the camera about to be described, 60 photographs in 
6 rows of 10 each are obtained on a 5 x 4-inch plate. 
A general idea of the appearance of the camera may be gained from 
fig. 1 , which for the sake of greater clearness is diagrammatic only , as are all 
the subsequent figures. A is a wooden upright, in the front of which is 
fixed the tube B carrying the lens. Behind A comes the “ carriage ” C, which 
rolls backwards and forwards by means of two wheels running on the top 
of A. To the back of C is attached a light metal frame F, which moves up 
and down C on guides, and in which is inserted the dark slide. It will be 
noticed that the upright A is slightly tilted ; this causes C, when free, to roll 
down DE to the lower end E. Similarly, when free, F falls down the 
guides on C. 
A horizontal slot is cut in C, so that the light from the lens tube B may 
pass to the plate behind. In order to exclude the entrance of extraneous 
light between A and C, a short camera bellows is attached to the front of C, 
and its plush-coated front edge rubs lightly against the back of A. A 
similar bellows is attached to F, and rubs against C. 
The mechanism of the camera is shown in fig. 2. The part of it which 
actuates the shutter is like an “ Atwood’s machine ” ; A with its weighted 
arms being the wheel, and B and C respectively the weights. C is a long 
strip of metal which moves up and down through the lens tube. A long- 
shaped opening is cut in the middle of it, and during each movement there 
is a brief interval when light can pass along the lens tube and reach the 
plate behind. The arms of the axle A increase its inertia, so that at the 
completion of each revolution it operates the lever D without fail. Below the 
weight B there is hung a weighted lever R, pivoted at P, which is shown 
drawn up by the cord attached to the pin of the disc F. As B is somewhat 
lighter than C, no movement will take place until the experimenter gives 
VOL. xxix. 12 
