The Optical Magic Lantern Journal (November 1900)

142 The Optical Magic Lantern Journal and Photographic Enlarger. Upon the interior of the fixed glass are painted in black the trestles of the swing (the positions of which are indicated by the dotted line z, Fig. III.). On the interior surface of the sliding glass Q, Fig. II., is glued a small block w, bearinga pin Pp. Thig pin fits in the slot 4 at the extreme top end of the swinging boat, as seen in the sectional diagram Fig. IV. The slide being now ready for exhibition, we will follow its action. When the sliding glass is pushed in, the swinging hoat being pivoted at B (Fig. III.) is caused, by means of the pin P working in the slot a, to swing up from left to right. At the same instant the distance between the pivot Land theend | of the boat occupied by the man becomes greater, whilst the length of the rod z is, of course, constant. The result of this is that the man is pulled up into a sitting posture. Meanwhile, the distance between the pivot m and the end of the boat occupied by the woinan becomes less, and consequently the woman is pushed down into a leaning attitude. The total effect obtained, therefore, is that of two persons in a swinging boat in motion—the woman in her turn pulling the rope, whilst the man is just resting after his “‘ pull,” and waiting for the next. When the sliding glass is pulled out the actions are reversed. The boat swings up from right to left, and the man, leaning out of the boat, tugs strenuously at the rope, whilst the woman receives her well-earned rest. The reader observes that the man is made to lean out of the boat—apparently pulling bard at the rore—by reason of the fact that the distance between L and the end of the boat as it swings up becomes less, the length of the rod z remaining constant. A similar reasoning will explain the action of the woman. When the sliding glass is pushed in and out, therefore, the effect as seen upon the screen will be that of a man and woman in a swinging boat in motion ; and, to all appearances, they, by their own efforts in pulling, keep on swinging the boat. To givea realistic effect, the operator would, of course, see that the sliding glass was so manipulated that, starting from rest, the boat would gradually swing higher and higher, and after a time, would gradually slow down, until it was once more stationary. = SOoo< on Hints to Would-be Lanternists. By THOMAS BYFORD. EO: (Sc Ever build up in order to get the | lantern on a level with the screen. Village This entails a lot of useless labour when a canting board would serve the purpose admirably. If not possessed of this useful article, a few books placed underneath the front : of lantern would do the necessary tilting. It would be well to bear in mind that it means money to transport big lumber from one village to another. Limit your luggage and your ex’s will be limited. The lectures sold with lantern sets are in most cases too long. Village folk do not like long lectures; let them be short, but always to the point. The more humorous the lecture, the better it will be appreciated. Don’t attempt to learn the lecture and give it as extempore if your retaining powers are not good—it only spoils the show; far better read it, which after all is no doubt the best plan. Don’t talk as if you have a plum in your mouth; speak slowly and deliberately in a natural tone of voice, which will penetrate to every corner of the room. Itis quite an easy matter after a little practice to manipulate the lantern and read the lecture at the same time. A small reading lamp (those with a candle are best) should be