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BLIND MAN'S SINGING SCHOOL, a game played by any number of persons, one of whom is blindfolded and takes the part of teacher, while the others personate scholars. The scholars sing the scale, each singing one note, in order, to the syllable "Ah." They can sing correctly or not, as they please. When the teacher thinks he recognizes a voice, he says Stop!" and, calling the scholar by name, makes some correction or criticism. If the name is given incorrectly the singing goes on; but if it is right, the scholar and teacher must change places. After the new teacher is blindfolded, the pupils must change seats, so that they cannot be recognized by the directions from which their voices come.

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the blotting-paper soaks out some of the water from the inside of the glass, reducing the pressure there, and so the pressure of the air outside holds goblet and glass together.

With care the glass or plate can be dispensed with and the experiment performed with the paper alone.

BLOWPIPE, Experiments with the. The ordinary blowpipe is a metal tube shaped as shown in the illustration. When the short end (which is usually made of platinum

Blow

pipe.

to prevent its melting) is placed in a flame and the mouth applied to the other end, a long, pointed, very hot tongue of flame is produced by blowing. The flame may be that of a candle, an alcohol lamp, or a gas burner. If a candle BLOCKADE, a SOLITAIRE game is used, the wick is bent of CARDS, played with two full packs. over at right angles so as The Kings and Aces are placed in not to interfere with the two rows as they come from the Fig. 1. blowpipe. If gas is used, pack. On the Kings, families are a flat brass tube is slipped built by piling downward, and on the over the burner as shown Aces, upward. Cards which cannot in Fig. 2. Fig. 3 represents be so used are placed in rows of ten the blowpipe flame. Blowpipes, each, face upward, on the table, one burners, and everything needed for row directly below another. Any the experiments described in this card in the upper or lower row may article can be bought be used in building, or any card of any dealer in having an empty space above or below it. Those having other cards above and below them are said to be blockaded, and cannot be used. When all the possible cards have been played at any time, the spaces must be filled in regular order from the pack. The player has the privilege of using one blockaded card in building, after the pack is exhausted. BLOTTING-PAPER, Experiment with. Fill a goblet to overflowing with water, lay over it a thick sheet of blotting-paper, and on this place a pane of glass, or a plate. After the water has soaked a little into the paper the goblet will adhere to it so strongly that it may be picked up by the glass and even made to stand out sidewise from it. The reason is that

an

chemical supplies.
The flame, as shown
in Fig. 3, consists
of a central blue
part, B, and
outer part A, of an-
other color. Either
of these parts may
be made larger at
the expense of the
other by varying the
force of the breath, as will be found
by experiment.

Fig. 2.

Burner.

Blowing. It is often necessary to keep the flame steady for several minutes. In order to do this, the operator must be able to take breath through his nose, while blowing. The effort should be simply to keep the cheeks constantly distended,

letting their elasticity drive the air The lead came from the lead oxide, out through the pipe.

EXPERIMENTS.

1. Melting. Take a small platinum wire or a bit of lime, and hold it in various parts of the blowpipe flame. (Objects may be so held by a pair of platinum forceps.) The wire will shine more brightly in some places than

Fig. 3.

others, and it will thus be found that the hottest part of the flame is just at the tip A (Fig. 3), where it is almost invisible. Hold various substances, bits of glass, stone, or metal in this part of the flame, and it will be found that some melt easily in it, while others do not.

2. Oxydizing. Near the end of a strip of fine charcoal make a cavity by pressing the edge of a coin on it and turning it around. Put in the cavity a bit of lead or antimony and hold it in the tip of the flame A. The heat will oxydize it, that is, cause it to unite with the oxygen of the air. A colored film or coating of the oxide will form around the metal. Other metals may be tried in the same way. Some will form colored films and others will not.

3. Reducing. Mix together small equal qualities of dry washing soda and lead oxide. Put a little in the charcoal cavity, and heat it in the inner blue part of the flame, near the tip B, regulating the flame so that the mixture is surrounded by it. After a time little globules of lead will be seen in the mass. It may then be cooled, put with water into a little mortar and broken up, when the beads of lead can be picked out.

whose oxygen left it to unite with the gases of the blue flame. This is called reducing and the blue flame is called the reducing flame. Oxides of other metals may be treated in like manner.

Borax Beads. Fix a piece of platinum wire in a cork for a handle, and make a little loop at the end of the wire. Heat the loop red hot and dip it into powdered borax, some of which will stick to it. The borax may now be melted to a transparent bead, which will remain on the wire loop. This bead has the property of dissolving many of the oxides of metals, which give it different colors, as may be seen by trial. A minute speck of oxide is sufficient. If the bead be then held in the reducing flame, the metal may often be obtained from the oxide, forming a globule in the center of the bead, whence it may be taken out, when cool, by breaking with the hammer.

BLOW THE FEATHER, a game played by any number of persons sitting in a square around a stretched sheet, which they hold just below their mouths. On the sheet is placed a feather, which each must try to keep away from him by blowing it toward some one else. If it touches any one he pays a forfeit. The game is played also by persons sitting around a table and trying to keep the feather in the air by blowing it. If any player allow it to fall to the table in front of him, or to touch him, he pays a forfeit.

The game is sometimes called "French and English," in which case the players divide into two parties, which sit on opposite sides of the room. The room is divided into two "Camps " by a line drawn through the middle. Each side chooses a champion, who strives to blow the feather so that it will fall to the ground in the opposite Camp. When one succeeds, the other becomes a prisoner and leaves the game. He is replaced by a second

champion, and the game goes on till all on one side have been taken prisoners.

BLUE VITRIOL, Experiments with. Blue Vitriol, or Sulphate of Copper, is described in C. C. T. under VITRIOL. If the blue liquid left in the flask in making SULPHUR DIOXIDE be evaporated over a water bath, crystals of blue vitriol will finally appear.

1. If a crystal of blue vitriol be heated in a test-tube, it will turn to a white powder, and water will condense in the upper part of the tube. A drop of water on the powder will at once restore the original blue color.

2. Make a strong solution of blue vitriol, and dip into it a knife-blade, carefully cleaned and free from grease. In a few minutes, copper will be deposited on the blade, making it look as if made of that metal. BOAT-BUILDING. Toy boats may either have hulls built of separate pieces or be cut out of a solid block. The latter method, being the easier, will be described first. The best wood to be used is evengrained, well-seasoned yellow pine. The dimensions of the block used for making a cutter yacht may be two feet long, five inches wide, and five inches deep, but the size and proportions may of course be varied to suit the builder. The block is first planed and squared, and then straight lines are drawn from end to end along the middle of two opposite sides. The ends of these are connected by similar lines across the ends of the block. All these lines must be carefully measured and drawn. On the side chosen for the deck a line is drawn across the middle at right angles to the long line, and then the deck plan is laid out as in the diagram. The curved lines must pass through the ends of the cross line, but their shape may be varied to suit the builder, provided the sides are exactly alike.

The first part to be shaped should

be the "counter," or overhanging stern, which is made as shown in the diagram at the place marked "After end of the block of timber." Curves representing sections across the hull at different points are now drawn on paper, and pieces of cardboard called section molds are cut out to fit them. The block is turned deck downward, and the wood cut away with chisel and gouge till it fits the proper piece of cardboard at each place. As the wood nears its final shape care should be taken not to cut away too much, and the molds should be applied frequently. Besides these cross sections, lengthwise sections may also be used, which will make the work still more accurate. Both sections are shown in the diagrams, and others may be tried experimentally by the builder, or copied from the lines of large yachts. The diagrams at the top and bottom of the page show a method of laying them off from a drawing. The lowest figure shows the sweep of the lines from bow to stern at different levels, the outside lines denoting their shape at the top and the inside ones near the keel. A set of horizontal lines for the different levels are then made as shown in the square figure to the left, which must be just as high as the block used. To find the shape of the cross section at any place, for instance the third vertical line from the right (marked C in the uppermost figure), measure off the distance of each curved line from the center, on the same line at the bottom of the page, and lay off the respective distances on their corresponding levels at the left. When the points so formed are joined, a curved line will result like that marked C in the small figure at the top, and this will be the shape of the section at C. In the same way the sections at the other vertical lines may be found and molds made from them.

The fullest part of the hull should be at the "midship section," or just half way between the stem and stern.

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The hull is now turned over and hollowed out with gouges, leaving the sides thick at first, and thinning them gradually. The upper half

Arrangement of Masts.

inch of the sides should be made very thin, for bulwarks, and a ledge should be left just below for the deck to rest upon. This is made of a thin piece of pine, cut to the proper shape. Some boats require a false keel to make them float properly. This is of lead, shaped in a mold made of three laths nailed together to form a narrow channel, which with the dimensions given above must be an inch and a half in depth and three-eighths of an inch thick. The channel is stopped at the ends with wood, so as to be exactly the length of the boat's keel. Six or eight nails are driven into the bottom of the mold, so that they will project from the lead keel when molded, and enable it to be fastened to the boat. The bottom of the mold should therefore be thin, so that it can easily be pulled away

from the nails. The mold is now filled with melted lead, which is taken out when it has hardened, and may then be shaped with a plane, as if it were of wood. The lower end of the false keel, at the bow, should be rounded.

Before nailing down the deck, holes must be bored in it for the mast and rudder. The hole for the mast in a boat of the size described should be half an inch in diameter, and eight inches from the bow. A similar hole must be bored part way through the bottom of the hull to fix the lower end. The mast should be half an inch in diameter, and is best made of pine. It is made in two parts, the lower of which must measure, between the deck and the topmast, just three times the greatest width of the vessel, in this case fifteen inches. Adding four inches for the part below the deck, and two and a half for the mast-head, the total length becomes twenty-one and a half inches. The mast must be rounded with a plane, or by whittling, and the mast-head (the upper two and a half inches) must be whittled down to half its diameter, to join it to the topmast. A quarter of an inch at the top must be made still smaller. The topmast is fastened to

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Ribs, Keel, and Keelson,

the lower mast by two "caps," seen in the illustration, the lower one resting on the lower part of the reduced portion, and the upper one fitting

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