The rays of light from “A” pass in a straight line through the lens “B” until they are interrupted by “C,” upon which they strike, forming an upside down image of the object “A.” But, you exclaim, “we do not see things upside down.” No, we do not, because some mental process readjusts this during the passing of the impression from the eye to our brain. Let us suppose we have our camera loaded with its sensitive plate or film. We select some object or view we wish to photograph, uncover the lens for an instant, and let the light impress the image upon the sensitive surface of the plate or film. Now, how are we going to make this image permanent? If we were to examine the creamy yellow strip of film upon which the picture was taken there would seemingly be no difference between its present appearance and before the snapshot was made. Now let us suppose that this strip of film is a little trundle bed, and in it tucked securely away from the light are many hundreds of little chaps called silver bromides, little roly-poly fellows lying just as close together as possible, and protected by a coverlet of pure white gelatine. ~HOW A PHOTOGRAPH IS DEVELOPED~ Until the sudden flash of light in their faces when the picture was taken, they have been content to lie still and sleep soundly. Now they are seized with a strange unrest, and each little atom is eager to do his part in showing your picture to the world. Alone they are powerless, but they have, all unbeknown to them, some powerful chemical friends, who, organized and aided by the photographer, will bring about their transformation. These chemicals, with the help of the photographer, form themselves into a society called the developer. The photographer takes just so many of the tiny feathery crystals of pyro, just so many of the clear little atoms of sulphite of soda, and just so many little crystals of carbonate of soda, and tumbles them all into a beaker of clear cold water. Unaided by each other, any one of these chemicals would be powerless to help their little bromide of silver friends. The first of these chemicals to go to work is the carbonate of soda. He tiptoes softly over to the trundle bed and gently begins turning back the gelatine covers over the little bromide of silver chaps, so that Pyro can find them in the dark. It is Pyro’s mission to transform the little silver bromides into silver metal, but he is rather an impulsive chap, so he is accompanied by sulphite of soda, who warns him not to be too rough, and whose sole mission is to strain his eagerness to help his friends. “Go slow now,” says Sulphite, “don’t frighten the little silver bromides, or else you’ll make them cuddle up in heaps, and the picture won’t be as nice as if you wake them up gently and each little bromide stayed just where he belonged.”