Gum first two circular pads of paper on each side of the spot where you intend to cut your bottle. These pads are obtained by gumming several strips of paper one over the other, so as to leave between them a groove on which you wind the string round once. Catch hold of the extremities of the string, and draw it to and fro, see-saw fashion, by which friction the part of the glass operated on will be heated. [Illustration] As soon as you think that the glass is hot enough, plunge the bottle in cold water, which you will have placed handy before, and at the spot where the friction was exercised the glass will be clean cut. According to the thickness of the glass, more or less heat must be produced. This process is infallible. The same result can also be produced in another way. It is, when once the heat is sufficient to let glide a few drops of water along the string. The string must be well wetted. The cut will be as clean as by the other process. Equilibrium of a Knife in Mid-Air. Be reassured dear readers, we are not going to ask you to make a balance in mid air, that would be too much for our weak capabilities. The question is simply to swing a knife horizontally in the space which surrounds us. The experiment is curious and easily executed. [Illustration] Take the cork of a champagne bottle. Pierce it lengthwise with a sharp knife, and let the knife stick out a third of its length from the thin end of the cork. Then insert into each side of the cork the prongs of two forks, so that they are perpendicular with the blade of the knife as shown in figure. This operation accomplished, you have only to suspend the point of the blade on the loop of a string, and the knife will hang horizontally. You may then swing it if you choose, and the movement will not destroy the equilibrium. A Trick With Four Matches. Speaking of matches, there is yet one more trick to be played with four of them. At the non-phosphoric ends of two matches cut a small notch so that they fit into each other. Stretch the matches apart so as to form an angle, and place them vertically upon the table. Then lean a third match against them so as to form a tripod, standing by itself. The question now is to take up this trivet with a fourth match and carry it to another place without disturbing the harmony of the little construction. [Illustration] At first sight this seems impossible; it is, however, easily done. You have only to slide the fourth match between the two stuck together, and the one serving as support. By lightly pressing against the two first ones the third one will slide, and its upper extremity will come between the angle formed by the two others. By taking it up briskly, this extremity will be maintained, and you are then enabled to carry the little tripod to another place. The Distance of an Inaccessible Point.