The science of optics affords an infinite variety of amusements, which cannot fail to instruct the mind, as well as delight the eye. By the aid of optical instruments we are enabled to lessen the distance to our visual organs between the globe we inhabit and “the wonders of the heavens above us;” to watch “the stars in their courses,” and survey at leisure the magnificence of “comets importing change of times and states;” to observe the exquisite finish and propriety of construction which are to be found in the most minute productions of the earth;--to trace the path of the planet, in its course around the magnificent orb of day, and to detect the pulsation of the blood, as it flows through the veins of an insect. These are but a few of the powers which this science offers to man; to enumerate them all would require a space equal to the body of our work; neither do we propose to notice the various instruments and experiments which are devoted to purposes merely scientific; it being our desire only to call the attention of our juvenile readers to such things as combine a vast deal of amusement with much instruction, to inform them as to the construction of the various popular instruments; to show the manner of using them, and to explain some of the most attractive experiments which the science affords. By doing thus much, we hope to offer a sufficient inducement to extend inquiry much further than the information which a work of this nature will enable us to afford. The Camera Obscura. This is a very pleasing and instructive optical apparatus, and may be purchased for a small sum. But it may be easily made by the young optician. Procure an oblong box, about two feet long, twelve inches wide, and eight high. In one end of this a tube must be fitted containing a lens, and be made to slide backward and forward, so as to suit the focus. Within the box should be a plain mirror, reclining backward from the tube at an angle of forty-five degrees. At the top of the box is a square of unpolished glass, upon which, from beneath, the picture will be thrown, and may be seen by raising the lid. To use the camera, place the tube with the lens on it opposite to the object, and having adjusted the focus, the image will be thrown upon the ground glass, as above stated, where it may be easily copied by a pencil or in colors. The Magic Lantern.