The next thing is to propel it through the air so that it will return to your feet; to do this, lay the boomerang on a flat book, allowing one end to project about an inch; then, holding the book to a slight angle, strike the projecting end of the boomerang with a piece of stick, or heavy pen-holder, when it will fly across the room and return to your feet. The Balanced Turk. A decanter or bottle is first obtained, and in its cork is placed a needle; on this is balanced a ball of wood, having a cork or wooden figure cut out, standing on the top. From the ball project two wires, bent semicircularly, having at their extremities two bullets. Push the bullets, and the whole will turn around on the needle, the figure standing upright all the while; and, twist it about from side to side as much as you like, it will always regain its erect position. The two bullets in this case cause the center of gravity to fall below the ball on which the figure is placed, and, in consequence, as the center of gravity always assumes the lowest position, it cannot do so without making the figure stand erect, or, in other words, until the bullets themselves are equally balanced. Any boy may whittle one of these toys out with a jack-knife. The Complacent Vizier. Among the novelties which scientific investigation has added to our toys, are several figures which will raise themselves upright when thrown down, and regain the erect position, notwithstanding their equilibrium is disturbed. The figures themselves are made of the pith of elder trees, or any other very light substance. Each is placed on half a bullet, or may be made to stand on its head, by making its cap of lead. Their appearance is very droll when they are moved about, as they seem every moment to be falling over, and yet continually right themselves. The philosophy of this is, that the center of gravity being in the base, and always trying to assume the lowest position, it keeps the figures upright. However much the equilibrium is disturbed, it will always try to regain its original position. ARITHMETICAL AMUSEMENTS. As the principal object of these articles is to enable the young reader to learn something in his sports, and to understand what he is doing, we shall, before proceeding to the curious tricks and feats connected with the science of numbers, present him with some arithmetical aphorisms, upon which most of the following examples are founded: Aphorisms of Number. 1. If two even numbers be added together, or subtracted from each other, their sum or difference will be an even number. 2. If two uneven numbers be added or subtracted, their sum or difference will be an even number. 3. The sum or difference of an even and an uneven number added or subtracted will be an uneven number. 4. The product of two even numbers will be an even number, and the product of two uneven numbers will be an uneven number. 5. The product of an even and uneven number will be an even number.