Our first engraving shows one of the prettiest optical illusions that can well be imagined, and it is produced thus: Provide a box, A, having in its front a round hole, B, in which may be fitted an eyeglass or small magnifier ; on the bottom of the box, and suspended by axles passing through the sides, place two rollers, C, and roll up on the first a quantity of paer having trees, houses, patterns, pieces of wall paper, pieces of printed muslin and similar articles having colored devices upon them; then paste or gum the other end of the paper to the other roller, so that when turned it will wind it upon itself and unwind it from the other roller Then place two pieces of lookingglass in the position shown at E E, leaving them free for the paper to roll under Now look through the hole, B (having just uncovered the top to admit of light), and by a handle or other means turn the back roller, C, and in the mirrors there will appear to be two endless panoramas ever changing and always advancing ; then turn the nearest roller, and the panoramas will appear receding, ever fresh and lively Our next is a little experiment illustrating the compressibility of air and water, called the "bottle imps" Take a jar of glass, and fill it with water up to the neck ; next provide a little figure having a hole in its center that will contain sufficient air to make it buoyant Put it in the water, and close the bottle with a piece of parchment or indiarubber tied tightly over the mouth Now when the hand is pressed on the cover, the figure descends, and when it is removed, the figure quickly ascends, and so it may be kept dancing up and down for any length of time The reason is this:The water in the bottle is incompressible ; when, therefore, you press upon the surface, it rises in the interior of the figure, and consequently by compressing the air into less space, renders the figure less buoyant; but no sooner is the hand removed than the inclosed air resumes its former volume, and expels the intruding water ; in consequence, the figure regains its former lightness, and reascends Summer is close at hand, the trees are beginning to wear their livery of green, and the flowers and plants push their small heads into notice from the bosom of mother Earth It is now no longer healthy or proper to stay indoors, trying experiments, when outdoor exercise can be so conveniently and properly had; and so we know that kite flying, marbles and spinning tops will take the place of ink door amusements, and our " Science in Sport" j S will have but little chance of being read We recommend our juvenile readers, to whom this column has been specially addressed, to do all they can to render their bodies strong with fresh air and healthy active exercise, that their minds may also be the stronger, and more able to think for them with vigor and freedom Hoping that they part with this column, as we do, namely, with some regret; and also hopingthat it has been a source of amusement and information to many, for the present, " Science in Sport" bids them Farewell!