camera obscura can now be fixed and rendered permanent,--not yet in all their various shades of colour, but in a style scarce less striking, and to which the limner, as if by anticipation, has already had recourse. The connoisseur unacquainted with the results of the recent discovery, would decide, if shown a set of photographic impressions, that he had before him the carefully finished drawings in sepia of some great master. The stronger lights, as in sketches done in this colour, present merely the white ground of the paper; a tinge of soft warm brown indicates the lights of lower tone; a deeper and still deeper tinge succeeds, shading by scarce perceptible degrees through all the various gradations, until the darker shades concentrate into an opaque and dingy umber, that almost rivals black in its intensity. We have at the present moment before us--and very wonderful things they certainly are--drawings on which a human pencil was never employed. They are strangely suggestive of the capabilities of the art. Here, for instance, is a scene in George Street,--part of the pavement; and a line of buildings, from the stately erection at the corner of Hanover Street, with its proud Corinthian columns and rich cornice, to Melville's Monument and the houses which form the eastern side of St. Andrew Square. St. Andrew's Church rises in the middle distance. The drawing is truth itself; but there are cases in which mere truth might be no great merit: were the truth restricted here to the proportions of the architecture, there could be nothing gained by surveying the transcript, that could not be gained by surveying the originals. In this little brown drawing, however, the truth is truth according to the rules of lineal perspective, unerringly deduced; and from a set of similar drawings, this art of perspective, so important to the artist--which has been so variously taught, and in which so many masters have failed--could be more surely acquired than by any other means. Of all the many treatises yet written on the subject, one of the best was produced by the celebrated Ferguson the astronomer, the sole fruit derived to the fine arts by his twenty years' application to painting. There are, however, some of his rules arbitrary in their application, and the propriety of which he has not even attempted to demonstrate. Here, for the first time, on this square of paper, have we the data on which perspective may be rendered a certain science. We have but to apply our compasses and rules in order to discover the proportions in which, according to their distances, objects diminish. Mark these columns, for instance. One line prolonged in the line of their architrave, and another line prolonged in the line of their bases, bisect one another in the point of sight fixed in the distant horizon; and in this one important point we find all the other parallel lines of the building converging. The fact, though unknown to