Illustrated descriptive catalogue of optical, mathematical, and philosophical instruments - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1848 Excerpt: ...and may be supported at a proper angle by a wire for the purpose. The prints are laid on the table, and viewed in the mirror through the lens, producing a very deceptive appearance, and in imagination bringing the reality before you. The frame is of polished wood, and may be taken apart by unscrewing for convenient transportation. This instrument, used for magnifying prints, is neat in its appearance and useful in its application; pictures are very interesting to children, and give them a very just idea of the relative size and distance of objects; they also teach them accuracy of sight, engage their imagination, and fix their attention, promoting many inquiries, which, if judiciously answered, will store their minds with useful information. Good perspective views designed for this instrument, handsomely colored, fourteen inches by twenty-two in size, embracing views of many of the most celebrated public buildings of the principal cities in Europe, interiors of public buildings in Rome, London, fcc., views of shipping, landscape views, &c, to the number of one hundred and upwards, may be obtained with the instrument, for the low price of eight cents each, which is not one half the price usually charged. Price, diagonal print glass with 4 inch lens, $2.75. "5" "$3.25. "6 ' "$3.75. "prints, 14 by 22 inch, per dozen, $1.00. "" "hundred, $8.00. The Portable Camera Obscura.--(Fig. 702.)--This consists of a box usually about twelve inches long, having one end attached to a movable slide, which ma' be drawn out a few inches, in which is fixed a convex lens, of a suitable focus; within the box is placed diagonally a mirror, so as to reflect the object on a ground glass, occupying nearly half of the top of the box, an...