The following, among many others, are some of the objects on which I have tried many amusing experiments with telescopes fitted up with the long tubes to which I allude. The telescope to which I shall more particularly advert is an achromatic, mounted on a pedestal, having an object-glass about 19 inches focal length, and 1-5/8 inch diameter, with magnifying powers for distant objects of 13 and 20 times. When this instrument is directed to a miniature portrait, 3-1/2 inches in length, placed in a good light, at the distance of about 8 or 10 feet, it appears as large as an oil-painting four or five feet long, and represents the individual as large as life. The features of the face appear to stand out in bold relief: and perhaps there is no representation of the human figure that more resembles the living prototype, than in this exhibition, provided the miniature is finely executed. In this case the tube requires to be pulled out four or five inches from the point of distinct vision for distant objects, and consequently the magnifying power is proportionally increased. Another class of objects to which such a telescope may be applied is _Perspective prints_, either of public buildings, streets or landscapes. When viewed in this way they present a panoramic appearance, and seem nearly as natural as life--just in the same manner as they appear in the Optical Diagonal Machine, or when reflected in a large concave mirror--with this advantage, that, while in these instruments the left hand side of the print appears where the right should be,--the objects seen through the telescope appear exactly in their natural position. In this case, however, the telescope should have a small magnifying power, not exceeding 5 or 6 times, so as to take in the whole of the landscape. If an astronomical eye-piece be used, the print will require to be inverted.