But, 15. With a pair of compasses draw six or eight concentric circles, as near one another as possible. Make four dots, dividing the outermost circle into equal parts, and then join these dots by straight lines, drawn with the aid of a ruler. (Fig. 3.) These lines will appear to be curved inward. This is because they cross the circles at different angles. elastic bands. Buy of an optician wall about it will continue to appear what is called a double-refracting blue, even when the candle is put prism, a piece of Iceland-spar or out, but on removing the roll from calc-spar which makes objects seen the eye, it seems white again, and through it appear double. Hold the cannot be made to look blue except card up to a window or lamp and by lighting the candle a second time. look through a prism at it. Each colored hole will appear double, and by holding the prism at the proper distance, one color can be made to overlap the other, so that the eye sees a mixture of the two. Note what this is. Now unfasten the bits of glass and look through both together at the light. The mixed color is entirely different from that obtained before. The reason is that in the first case one color really added its effect to the other, whereas in the second case the color seen is merely that remaining after each glass has strained certain colors out of the sunlight. Thus, suppose blue and yellow glass be tried. A mixture of pure blue and yellow light makes white, so the color seen through the prism will be whitish gray. when looked through together the glasses will appear green, because the rays of light are the only ones which will pass through both yellow and blue glass. In the same way red and green appear orange by the first method and dark green by the second; red and blue seem first violet and then deep red; and yellow and red appear first orange-yellow, then orange-red. 14. Darken the room and admit a little daylight (not direct sunlight) through an opening. With this throw the shadow of a rod or other object on a white wall or screen, and light a candle, so as to throw a second shadow. Alter the size of the opening through which daylight is admitted, so as to make the two shadows as nearly as possible of the same intensity The shadow thrown by the candle is really white, since it is the only part of the wall on which pure daylight shines alone, yet by contrast it appears blue. If it be looked at through a roll of black cardboard or paper the part of the Fig. 3.-Experiment 15. and the judgment of the observer cannot help attributing this, in part, to the curvature of the line. 16. Hold horizontally, a little below the eyes, a rod about a foot long, with its near end six or eight inches from the face and its opposite end pointing directly away. Look at the near end, and the two images of the rod will appear like a V. with the point toward the face. Fix the eyes on the farther end, and the V will have its point away from the face. 17. Press the closed eye with the finger tip close to the nose. A dark spot with a light border will be seen on the other side of the eye. If the eyeball be pressed on the outside the spot will be seen on the inside. 18. Rub or press the closed eyes for some time, and designs and spots of various shapes and colors will be seen changing of themselves or according to the varying pressure. These spots are all caused by the excitement of the optic nerve by pressure. 19. Draw a number of lines converging to a point toward either the right or the left, and then draw several upright lines of the same length across these as in Fig. 4. If any one side down and look at the same letter. What is now the bottom appears much the smaller part. The reason is that the eye tends to magnify the upper part of a figure. For this reason the lower half of the S's are usually made a little larger than the upper, to balance this tendency, but when the letter is inverted | the larger half is now at the top and so looks larger still. 22. Cut out two pieces of paper of exactly the same size, shaped as in Fig. 4. Experiment 19. who does not know, be asked which is the largest of the upright lines, he will be apt to point out the one crossed by the greatest number of the converging lines. 20. After reading for some time with one side toward a window, close the eyes alternately, and it will be seen that the paper of the book has a greenish tinge when seen by that eye alone which was next to the window. This effect is stronger if the light be very bright. The reason is that the light, shining through the blood-vessels in the eyelid, tries that part of the eye that appreciates red, and so a white page appears to it slightly tinted with the complementary or opposite color, Fig. 5.-Experiment 22. Fig. 5, and place them as there shown. The eye will usually judge, at first sight, that the lower is the longer. If the pieces be made of different colors, to distinguish them, and their places be changed, one will seem to have decreased and the other to have increased. 23. Make a pinhole in a card and hold it three or four inches before the eye. Hold a pin-head as close to the eye as possible and it will be seen, upside down, in the pinhole. This is because, though the pin is much too near the eye to form an image on the retina, the ray of light through the pinhole causes it to cast a shadow there. This shadow is upright, whereas the images of objects are inverted, so, as they appear right side up, the shadow appears upside down. If several pinholes be made instead of one, the pin-head will be seen in each one of them, because each ray of light throws a separate shadow of the pin-head on a different part of the retina. Any The appearance is due entirely to object of similar size may be used in- the diagonal lines above and below stead of the pin, and if it be moved them. in any direction the shadow will be 25. Look at anything having a seen to move in the contrary direc- regular pattern, such as a piece of tion. If the eyelashes be allowed to figured cloth or calico, or better still fall over the eye, their shadows will be a piece of wire netting or the seat of seen to move upward in the pinholes. a cane-bottomed chair. By relaxing 24. Look at Fig. 6. The horizon-the eyes so that they will be fixed on tal lines appear to be nearer to- a point beyond the object, the two gether at the middle than at the images of the figured surface may ends, but this is not so. They be made to appear to slide one over are quite straight and parallel. the other, and by practice may be Fig. 6.-Experiment 24. cannot direct his eyes to one point while noticing another he should hold his finger either in front of the surface or behind it, and look directly at it, trying at the same time to watch the figures on the surface. made to stop where the observer figures smaller. If the observer pleases. If he thus causes the image of each figure to coincide with the one next to it, the surface will seem farther from his eye and the figures larger. If he causes the images to overlap still more, so that each falls on the second one from it, the effect will be increased, and so on. If he fixes his eye on a point nearer him than the surface, the latter will appear nearer, and the This experiment requires considerable practice, and some people find it more difficult than others. When properly done the effect is striking. 26. Darken the room and cover the image on the retina is disone window with cloth or paper torted. having the figure of a cross cut 27. View a straight line, a, through through it. Look steadfastly at this for a few seconds and then look at the wall of the room. The "after image" of the cross will be seen. If the eye be now directed, without moving the head, to one of the corners of the room the arms of the cross will appear twisted so that the cross will look thus or thus. This is because the eyeball is twisted a little in turning it toward the corner of the room, so that F Fig. 7.-Experiment 27. a pinhole, o, in a card, as shown in Fig. 7. It will appear to broaden as it nears the eye. FABA-BAGA. See BEAN BAGS. | may be moved to any adjacent unFAGGOTS. See Fox AND occupied angle, forward, backward, GEESE, II. FAMOUS NUMBERS, a game played by any number of persons, each of whom writes a number on a slip of paper. The slips are mixed in a hat, and each player draws one. Each in order must then explain for what the number he drew is famous, or pay a forfeit. For instance, the number three may be said to be celebrated on account of the Three Graces. Two for Shakespere's "Two Gentlemen of Verona." Ten for the Council of Ten, and so on. FANORONA, a game played by two persons, with 22 white and 22 black pieces or men, arranged on a Fanorona Board. board like that shown in the diagram. The players sit opposite each other, and take turns in moving. A piece diagonally, or to either side. If, when any move is made, a piece is face to face with one of the enemy's, no vacant space being between, all of the enemy's pieces extending in unbroken line in the direction of attack are captured and removed from the board. If the line is interrupted by a vacant space, or hostile piece, the men are captured only as far as such space or piece. He who succeeds first in capturing all his opponents' pieces wins the game. RULES OF THE GAME. 1. The first player is allowed only one move. 2. After the opening of the game, each player is allowed to move, using any piece he pleases, so long as he continues to capture. When he ceases to capture, his opponent begins his turn. 3. A player must not return at once to a point he has just left. 4. A player must not capture in any direction immediately after making a capture in the opposite direc tion. Fanorona is the national game of the natives of Madagascar, who have reduced it to a science. In Madagascar a defeated player is not al lowed to play his second game on the same footing as the first, but must play a new form of it, called Vela. In this form the defeated player plays first, and the other exposes to capture such pieces as he chooses, till seventeen have been taken, but these can be taken only one at a time. Until the entire number are captured, the owner of them can make no captures. The game then goes on as in the ordinary way. A defeated player is allowed to play only the Vela game, till he has won a victory. FARM YARD, THE, a trick in the form of a game. One of the company, chosen as leader, tells the others that they must sit in a circle, and each personates some animal. He says that he will first whisper in the ear of each what noise he is to make, and that all must rise and make their noises at a given signal. He then whispers to each, directing them all to remain quiet, except one, whom he tells to bray like a donkey. When the signal is given, the victim of the trick rises and brays, while the others sit still. FARRAGO. See SYNTHESIS. FAST RUNNERS, a running game played by any odd number of persons. All but one are arranged in a column by pairs, all facing toward the same end of the column. The remaining player stands alone at the head of the column, and at a signal from him the two at the foot divide and run on the outside of the lines past the head, after which they take different directions. If the one at the head can catch either before they meet again and join hands, that one must take his place, and he becomes the partner of the other, standing close to the head of the line. If the couple join hands before either is caught, they stand close to the head, and the unsuccessful runner is at the head again. At the signal the couple now left at the foot begin to run in like manner, and so on till the players are tired. Neither of the runners " can be touched until he has passed the head of the column. In Germany this game is called Fang Schon (Begin now), and in Russia "It Burns," from the cries of the runners. In Belgium it is called Bride and Bridegroom," and in Suabia Brautlauf (The Bride Chase). These last names seem to show that it is derived from the old custom of requiring the bridegroom to carry off the bride by force, or pretend to do so. FEELING, Experiments on. I. Cross the forefinger and middle finger of one hand, and with the tips feel a marble or small pebble held in the palm of the other. It will feel as if there were two marbles. The reason is that the marble is felt at the same time by the two sides of the fingers which are usually farthest from each other, and the mind cannot help concluding that there are two marbles. The best way of performing the experiment is to let some one else cross his fingers, shut his eyes, and guess how many marbles he feels. If more than one held in the hand, guessing becomes still more difficult. 2. Prick a person's hand with two pins held very close together. It will be found that he cannot tell when you use two points and when only one, provided the points touch him exactly at the same time. On some parts of the body the pins may be held about half an inch apart before the two separate pricks can be feels. The reason is that the nerves of the skin form a network which is much closer in some places than in others. Where the meshes are very large the nerves cannot distinguish two sensations which are very near together. If blunter points be used than those of pins, the effect is more striking. 3. Take a long hair, and with the thumb and forefinger of one hand pull it through those of the other, first in one direction and then in the other. It will be found that it slips easily one way and will scarcely slip |