The smaller illustrations show the exact size of the pictures as they appear on the film. They are an inch wide and three quarters of an inch deep. A reel is usually a thousand feet long, and contains sixteen thousand pictures. On a screen twelve feet square, which is smaller than the usual size, there is surface enough to show twenty-seven thousand of the pictures side by side if they are reproduced without enlargement. Yet if every enlarged picture were shown on a separate twelve-foot screen, a single reel would require a stretch of canvas thirty-six miles long. Likewise a screen twenty feet square would accommodate over seventy-six thousand of the little pictures, and the stretch of canvas required for the enlarged pictures would be sixty miles long. After witnessing a performance, few realize that they have seen any such stretch of pictures as the figures show. [Illustration: By permission of “The American Quarterly of Roentgenology” and “The Archives of the Roentgen Ray” SERIES OF RADIOGRAPHS SHOWING THE MOTIONS OF A STOMACH SUFFERING FROM GASTRIC PERISTALSIS] The life of a film is usually from three to six months, though varying, of course, with the treatment in handling. “The Scientific American” gives credit for superiority to films of French make, and attributes their excellence to the many tests to which they are subjected to secure exact dimensions, adequate strength, and other properties. It is almost as vain to speak of the cost of producing a film as it is to speak of the cost of producing a painting. We know the cost of the canvas of the latter, and we also know the cost of the bare film is three cents per foot; but the cost of what is on the film may be represented only by the cost of developing and the labor of the machine-operator, as, for example, in such pictures as “An Inaugural Parade,” or the famous pictures showing the “Coronation of George V.” Sometimes, however, the cost runs as high as fifty thousand dollars, as did the film known as “The Landing of Columbus.” These films require many people, necessitate the taking of long journeys to provide an appropriate setting, and need from two to three years to finish them. Before the film known as “The Crusaders” was ready for the public, six hundred players and nearly three hundred horses had appeared in front of the lens. The film of “The Passion Play,” now in preparation, will cost, it is said, a hundred thousand dollars.