The portable camera obscura, represented by the diagram, has often yielded much pleasure in the domestic circle, while the larger ones, which are publicly exhibited, are highly interesting. No person, perhaps, has witnessed the neatness of outline, the precision of form, the truth of colouring, and the sweet gradations of tint, thus apparent, without regretting that an imagery so exquisite and faithful to nature could not be made to fix itself permanently on the tablet of the machine. Yet, in the estimation of all, such a wish seemed destined to take its place among other dreams of beautiful things; the splendid but impracticable conceptions in which men of science and ardent temperament have sometimes indulged. Such a dream, however, has been realized of late. [Illustration] Mr. Thomas Wedgewood, the celebrated porcelain manufacturer, so early as 1802, published, in the journals of the Royal Institution, a method of copying paintings upon glass, and of making profiles by the agency of light upon nitrate of silver. The experiments he made were repeated by sir Humphry Davy; but several years after, MM. Niepcé and Daguerre, and Mr. Fox Talbot, laid the foundation of the present state of photographic drawing. The former engaged in a long series of experiments to render metallic surfaces peculiarly sensitive; the aim of the latter was to produce this effect on paper. The camera obscura used for this purpose is a rectangular box, with a double convex lens, A, at one end, and a glass reflector, B, which is generally a piece of looking-glass, at the other. Now, supposing the rays of light to proceed from an extensive landscape, and pass through this small convex lens, as we well know they may do, what will be the effect produced? The scene will, in the first place, be thrown on the reflector, which is fixed at an angle of forty-five degrees to the horizon. Now it follows, from a law well known to opticians, that these rays will be reflected to the top of the box, immediately over the mirror; so that if a ground glass, or any other medium capable of receiving the reflected image, be placed there, a representation of the landscape may be observed. As then, it is proved, by innumerable experiments, that reflected light has, in proportion to its power, as much influence on prepared or photographic paper, as the direct rays of the sun; it follows that, if a piece of it be placed in the same situation as the ground glass, the reflected image, be it a landscape, a figure, or an artificial object, will be formed on it. All that is, therefore, required to be done, in using the camera obscura for photographic drawing, is to place upon the opening at the top of the box the prepared paper, and immediately to cover it with the lid, C, so that it may not be acted upon by any other light than that reflected from the mirror. The time required for producing the necessary effect will depend on several circumstances, such as the preparation of the paper