Take a common vial, or small bottle, cut off the rim by using the hot poker as directed above. Let the vial now be nearly filled with common rain water, and applying the finger to its mouth, turn it quickly upside down: on removing the finger it will be found that only a few drops will escape. Without a cork or stopper of any kind, the water will be retained within the bottle by the pressure of the external air, the weight of the air without the vial being so much greater than the small quantity within it. Now let a bit of tape be tied round the middle of the bottle, to which the two ends of a string may be attached, so as to form a loop to hang on a nail; let it be thus suspended in a perpendicular manner, with the mouth downward: and this is the barometer.
When the weather is fair, or inclined to be so, the water will be level at its lower surface, or perhaps concave, like an individual butter plate turned upside down; but when disposed to be stormy, a drop will appear at the mouth, which will enlarge till it falls, and then another drop, so long as the humidity of the atmosphere continues.
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AN INFALLIBLE BAROMETER.
With a few cents any boy can buy the chemicals required for this barometer, and obtain an instrument much more reliable than many of the cheaper grades for sale in the stores. Put two drams of pure nitrate of potash, and half a dram of chloride of ammonium reduced to a powder, into two ounces of pure alcohol, and place this mixture in a clear glass bottle, covering the top with a piece of rubber or thin kid pierced with small holes.
If the weather is to be fine, the solid matters remain at the bottom of the bottle, and the alcohol is as transparent as usual. If rain is to fall in a short time, some of the solid particles rise and fall in the alcohol, which becomes somewhat thick and troubled. When a storm, tempest, or even a squall is about to come on, all the solid matter rises from the bottom of the bottle and forms a crust on the surface of the alcohol which appears to be in a state of fermentation. These appearances take place twenty-four hours before the tempest ensues, and the point of the horizon from which it is to blow is indicated by the particles gathering most on the side of the tube opposite to that part whence the wind is to come. The longer the diameter of the bottle the better for this kind of barometer.
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THE BALANCING DOLL.
From a piece of soft wood whittle out a head and body like that in the illustration, making slits on either side for the insertion of the wings. These oar-shaped appendages are generally made from a shingle, and are affixed to the body by pressing them firmly into the slits. The whole thing can be painted to suit the fancy; water colors spread on rather thickly answer quite as well for small objects of this class, if protected by a good coating of varnish, made by dissolving a few cents’ worth of white shellac in a small quantity of alcohol. It is important that the oars are of the same weight and placed at equal angles with the body for this plaything to be successful.