272 Lord Rayleigh on Some Applications of Photography. [Feb. 6, 



The limits of an ordinary portable camera are thus soon passed. 



The original of the transparency now to be thrown upon the screen 



was taken in an ordinary room, carefully darkened. The aperture 



(in the shutter) was -07 inch, and the distance of the 12 X 10 



plate from the aperture was 7 feet. The resulting picture of a group 



of cedars shows nearly as much detail as could be seen direct from 



the place in question. 



[R.] 



