30 Photography for the Sportsman Naturalist 



The principles of the projecting of images of 

 objects by means of light rays were known, how- 

 ever, a long time before the camera was invented. 

 About the middle of the sixteenth century an 

 Italian by the name of Baptista Porta invented 

 the " camera obscura," which, as its name implies, 

 was nothing more or less than a darkened room 

 to which light was admitted only through a single 

 small hole in the window shutter. We can any 

 one of us easily repeat his experiments by tightly 

 closing the windows of a room with dark shades 

 and through one shade cutting a small hole. On 

 the wall opposite this window hang a sheet, and, 

 when the sun is shining, we can see a faint, in- 

 verted image on the sheet of whatever the window 

 may look out upon. It is inverted because the rays 

 of light emanating from the bottom of the object 

 looked upon pass upward at an angle, and, enter- 

 ing through the hole in the shade, strike the sheet 

 at its upper edge, and vice versa. This is true 

 also of the modern camera. Porta somewhat 

 improved upon the primitive contrivance just 

 described by placing a double convex glass lens 

 in the aperture of the shutter, outside of which 

 a mirror was placed to receive the rays of light 

 and reflect them through the lens. The image 

 upon the screen was thus made much brighter 

 and more distinct, and was, moreover, shown in 

 its natural, upright position. Crowds flocked to 



