In addition to the stereopticon and its attendant mechanism, which is only suitable when the pictures are to be shown to an audience, a machine has been invented for the use of an individual or a small group of people. In the mutoscope the positives or prints are made on long strips of heavy bromide paper, instead of films, and are generally enlarged; the strip is cut up after development and mounted on a cylinder, so they radiate like the spokes of a wheel, and are set in the same consecutive order in which they were taken. The thousands of cards bearing the pictures at the outer ends are placed in a box, so that when the wheel of pictures is turned, by means of a crank attached to the axle, a projection holds each card in turn before the lens through which the observer looks. The projection in the top of the box acts like the thumb turning the pages of a book. Each of the pictures is presented in such rapid succession that the object appears to move, just as the scenes thrown on the screen by a lantern show action. The mutoscope widens the use of motion-photography infinitely. The United States Government will use it to illustrate the workings of many of its departments at the World's Fair at St. Louis: the life aboard war-ships, the handling of big guns, army maneuvers, the life-saving service, post-office workings, and, in fact, many branches of the government service will be explained pictorially by this means. Agents for manufacturers of large machinery will be able to show to prospective purchasers pictures of their machines in actual operation. Living, moving portraits have been taken, and by means of a hand machine can be as easily examined as pictures through a stereoscope. It is quite within the bounds of possibility that circulating libraries of moving pictures will be established, and that every public school will have a projecting apparatus for the use of films, and a stereopticon or a mutoscope. In fact, a sort of circulating library already exists, films or mutoscope pictures being rented for a reasonable sum; and thus many of the most important of the world's happenings may be seen as they actually occurred. Future generations will have histories illustrated with vivid motion pictures, as all the great events of the day, processions, celebrations, battles, great contests on sea and land are now recorded by the all-seeing eye of the motion-photographer's camera. BRIDGE BUILDERS AND SOME OF THEIR ACHIEVEMENTS In the old days when Rome was supreme a Caesar decreed that a bridge should be built to carry a military road across a valley, or ordered that great stone arches should be raised to conduct a stream of water to a city; and after great toil, and at the cost of the lives of unnumbered labourers, the work was done--so well done, in fact, that much of it is still standing, and some is still doing service.