grounds at Fifth Avenue and 110th Street, New York City, still known as the Polo Grounds, though they are not now used for the purpose, the club having removed its headquarters to Newport, Rhode Island, where frequent matches are played every summer. A kind of Polo has long been played by the Indians of Arizona, who use any kind of a stick they wish, and strike to and fro any object, as a stone or piece of wood. There are no sides, each player acting for himself. POOL, See BILLIARDS. POPE JOAN. See NEWMARKET. POP-CUN, a toy gun worked by compressed air. The simplest kind is the Potato Pop-gun, which is made as follows: Fit loosely to a piece of goose-quill about three inches long, cut off squarely at the ends, a wooden piston or ramrod. Cut a raw potato into slices about as thick as a silver dollar, and press each end of the quill on a slice, so that both ends will be plugged with little pellets of potato (p). Ifone of these be now pushed in with the piston (s), the other will fly out with a popping noise. The air within is first compressed and then, expanding, drives out the bit of potato before it. The remaining piece is now pushed forward to the end of the quill, the vacant end pressed again on a slice of potato, and the gun is ready to be fired once more. S A larger gun can be made of a tube of brass or glass, with a piston made Pop-gun. by winding twine around the end of a stick till it will exactly fit the bore. A cork is inserted at one end of the tube and driven out by suddenly pushing the piston kind the piston is in the middle, and there is a cork at each end, so that it can be fired either by pulling or by pushing the piston. In another, a piece of paper fastened tightly over one end is broken by the force of the compressed air. POROSITY, Experiment on. Porous substances are those which are filled with minute holes, or pores. Half fill a glass with boiling water, and lay over the top a piece of pasteboard, over which invert an empty dry glass. The moist vapor arising from the water will soon be seen also in the upper glass, having passed through the pasteboard. In this way many kinds of substances may be tried: wood, cloth, Indiarubber, glass, etc., and it will be found that some of them are porous enough to let water vapor through them, while others are not. PORTRAITS, a game played with pen, ink, and paper by any number in at the other. Pop guns of all of persons. Each writes his name kinds are sold at toy shops. In one on a slip of paper, with as many E flourishes, and as much ink, as possible. Each then folds his paper once, the fold running lengthwise through the middle of the name, and passes it to the right. The person who receives it presses his A finger on the fold at A, then draws it from B to B C, from B to E, and from C to D. He thus makes a series of blots within, D and when the paper is unfolded, a rude and comical resemblance to a human figure will be found. This is supposed to be the portrait of him whose name was written on the paper. As a general thing, the more ink used in writing, the more amusing will be the por trait. C The picture shows an “autograph portrait" thus taken. The game is sometimes called "Smudgeography." PORTRAITS AND SENTIMENTS, a game played by any number of persons, who sit in a row. Each whispers to his right-hand neighbor the name of some person, and to his left-hand neighbor some sentiment, original or quoted, supposed to be written under the portrait of that person. Each then announces aloud whose portrait has been presented to him, and what is inscribed under it. For instance, a player may be given the portrait of Bluebeard with the inscription: "He was an indulgent husband, and an estimable gentleman." The names chosen may be those of the players, or those of famous characters, real or fictitious, ancient or modern. POTASSIUM, Experiments with. Potassium is described in C. C. T. 1. Throw a piece of potassium on water as described in C. C. T. 2. Throw a piece on a large sheet of blotting-paper which has been wet with red litmus water (see TESTPAPERS). The potassium will run about the paper, leaving a blue track caused by the formation of potash (see C. C. T.) 3. In a block of ice about six inches square, bore a hole half an inch wide and two inches deep, enlarging the bottom of the hole to form a cavity. Drop into it a piece of potassium the size of a pea. It will take fire and burn beautifully. The experiment should be tried in a warm, dark room. 4. To Fire a Cannon with an Icicle. Load a toy cannon, and on the gunpowder on the touch-hole put a piece of potassium as big as a pinhead. When this is touched with a piece of ice it will blaze up, setting fire to the powder. POTATO RACE, a running game played by any number of persons. A circle about forty feet in diameter is marked out as a racecourse, and across it at any point is marked a straight line A B ten feet Course for Potato Race. B long, half outside the ring and half inside. On this line spots are marked at intervals of six inches. Each contestant must take a potato from a basket placed near the ring at C, opposite the line, and running around the circle place it on the first spot on the line. As he goes on past the basket he takes another potato, which he places on the second spot, and so on till ten minutes have passed. After placing each potato the runner must return to the ring without stepping over the line, and each potato must be placed exactly on its proper spot. Three judges are appointed, one of whom stands at the potato basket, one at the line, and one in the middle of the circle to call out the runners' names in order and keep the time. Any runner who takes more than one potato, or fails to take any, who skips a spot, or does not place his potato properly, is declared out of the race at once. Instead of potatoes, apples, or any small objects can be used. The course and line may be marked with lime or flour on grass, and the spots for the potatoes with dark earth, or by short cross-lines. thus: the eldest hand names the suit he prefers, and then the others, in order, to the left; but each must name a suit higher in rank than the preceding player, or say "I pass." Hearts ranks as the highest suit, and after it, in order, Diamonds, Spades, and Clubs. The highest suit bid is taken for trump, unless some one bids "Preference," or says "I Prefer," when the game must be played without any trump. Preference is higher than any other bid, and as soon as it is bid, play begins at once. In practice, the bids of Clubs and POUND PARTY, an entertainment Spades are now used as an invitation to which each guest is required to to the player's partner to demand bring something weighing exactly a Preference, Spades being the pound. These may be eatables, stronger invitation. If all pass, the toys, useful articles, or whatever party may agree to play "Millissithe giver pleases. Each package is mo," the object then being to avoid numbered and laid aside as it is re-taking tricks. Honors and tricks are ceived. When the guests are ready for the distribution of the parcels, numbered cards, or slips of paper, are passed around and each draws one. Some one then takes the packages one by one, calling its number aloud; the holder of the corresponding number becomes its owner, and must open it in the presence of the company. PREDICAMENTS. QUESTIONS. See CROSS scored as in Whist, but the score is multiplied by 3, if Clubs are trumps; by 4, if Spades; by 5, if Diamonds; by 6, if Hearts; and by 8, if Preference or Millissimo has been played. In the case of Millissimo, not those who take the tricks, but their opponents, score. In addition, a Little Slam (12 tricks) counts 10 points, a Grand Slam (13 tricks) counts 20; the first game in a rubber counts 10, and the second (if won immediately after the first), 20. All these points remain the same, no matter what the trump is. PREFERENCE, or SWEDISH WHIST, a game of CARDS, played with a full pack, generally by four persons, but sometimes by five or six. A game ends when one party has The four-handed game will be de- made 20 points in tricks alone. A scribed first. The pack being placed rubber ends when two consecutive face downward on the table, each games have been won by the same player draws a card from it. The side. After the first rubber, the holders of the highest two play to-dealer and the player at his left gether as partners, the other two playing against them. The one who draws the lowest card is allowed to select his place at the table, and deals first. Ace is considered the lowest card in thus drawing, but in playing the cards rank as in WHIST. The game resembles ordinary Whist, but differs in the following points: The trump is determined by bidding keep their seats, and the others change. After the second, the player opposite the dealer changes with the one who has not played with the dealer. This series of three rubbers constitutes what is called a "complete game." Each player keeps his own score, crediting himself with all points made by himself and each of his partners, and after the third rubber, he who has most points is declared winner. As the end of the "small game" is determined by the points made by tricks alone, it is convenient to score them by themselves. When five play, one always stays out of the game, he who drew the highest card staying out of the first rubber, the next to the highest out of the second, and so on. Each, on entering the game, sits opposite the player who drew the lowest card. When six play, two stay out in like manner. PRISM, Experiments with a. The prisms used to separated white light into its different colors (see Light in C. C. T.) are three-sided. Such prisms are sometimes used also for ornaments on chandeliers or lamps. Larger ones are somewhat expensive, but a good prism can be made by fastening three squares of glass on a glass bottom, and filling with water the three-sided vessel so formed. The joints are made watertight with putty. EXPERIMENTS. 1. Look through a prism at the edge of any bright object, or at a sheet of white paper pasted on black Experiment 2. paper. It will appear colored, in narrow stripes of red, yellow, and blue. 2. Hold a prism P (see illustration), in a beam of sunlight admitted through a hole S, into the room. If possible, shut out all light from the room except the one beam. This may be done by closing the shutters at all windows but one, and covering that with sheets of thick wrappingpaper, in one of which is cut a small hole to admit the beam. The spot of light made by the beam on the wall or floor will show seven colors, which will be farther apart the larger the prism. The colors violet, indigo, blue, green, yellow, orange, and red are denoted in the picture at I H by their initial letters. 3. Take a bit of red sewing-silk, and hold it in each one of the colors. If the room is perfectly dark, the silk will appear black, or almost so, in each of them except the red. In like manner, yellow silk will appear black in each color except the yellow. This is because each piece of silk is able to reflect only its own color. 4. Look through a prism at the flame of an alcohol lamp in which salt has been dissolved. It will not appear colored at all, because such a flame is pure yellow and cannot be separated into other colors. This is the only pure color easy to obtain. 5. Receive the colored spot on a hand-mirror, so as to reflect it to the ceiling, and tip the mirror rapidly, so as to make the spot move backward and forward. It will appear white, because the effect is the same as if the colors were mixed together again. With the aid of a HELIOSTAT the colors can be separated muc farther, into a ban! called the spectrum. The beari of light from the heliostat should be admitted to the room through PRISONER'S BASE, an out-door game played by any number of persons, though the best number is from 12 to 16. Two "Bases," or enclosures, are marked off, each large enough to hold half the players, and two "Prisons" a little smaller, from one to two hundred feet from the Bases, according to convenience. Two methods of laying out the ground are shown in the diagrams. The players are divided B's A's A's B's Base a narrow slit from one-eighth each cuts off the light in a different to one-quarter of an inch wide. way. This slit may be cut in a sheet of paper which is pinned over the hole through which the light passes. In front of the slit is placed a lens at such a distance as to throw a clear image of the slit on the opposite wall, or on a handkerchief held up before it. The prism is then placed in front of the lens. The spectrum will be thrown to one side, where it must be received on a white wall or screen. This must be exactly as far from the prism as the wall or place where the clear image of the slit was formed, otherwise the spectrum will not be clear. If the wall is just at the right distance, and the slit is narrow enough, vertical black lines are seen across the spectrum. These black lines are caused by the sun's atmosphere, which stops some colors of light and lets others through. Colored liquids also let through part of the light and stop other parts, as may be seen by placing various liquids in the path of the ray. For this purpose a thin transparent vessel is needed. One may be made by fastening together with shellac varnish two pieces of window glass, about four inches square, an inch apart, by means of wood strips on three sides. Carmine dissolved in weak ammonia water, placed in this vessel and held in front of the light, either between the slit and lens, or between lens and prism, only lets through a little of the red light, if the solution is strong. When it is weakened, two upright black bands will be seen across the spectrum in the greenish-yellow part of it. A little blood, mixed with water, also gives two bands, but they are in a slightly different place from the carmine bands. This is an easy way of telling carmine from blood, though their colors are almost exactly alike. By trying all sorts of colored substances, dissolved in water, it will be found that B's Fig. 1. A's A's B's Base Fig. 2. Prisoners' Base Grounds. into two opposing sides, each of which occupies one of the Bases. A player from one side begins the game by running beyond the bounds of his Base, and one on the opposite side pursues him. A second man from the first party chases the pur |
