The cost of this lantern is nothing, for every amateur who practises photography has the materials required - viz., a green glass bottle and a jampot of white earthenware large enough to admit of the bottle being placed within it. Next cut off the bottom half of the bottle, by first holding the bottle over a candle, and then plunging it into cold water; this will establish a crack which is led round the bottle with a red-hot poker, thus cutting it into two parts; then place the upper portion with the neck into the jam-pot, neck upwards, and observe how far the neck appears above the jam-pot; this portion blacken with Brunswick or Japan black Then take the cork belonging to the bottle and cut a piece out of it, like Fig. 51, the cork being placed so that the heat and smoke can escape. The lantern is now complete. To use, place a night-light at the bottom of the jar, and the bottle over that (Fig. 52). The light should not be placed within 4ft. of the developing tray, or, if required nearer, a piece of orange paper should be placed over the jar, with a hole cut in it for the neck of the bottle. This light will not fog an extra-rapid plate.
A beer bottle will do for the bottle.
(6) Reflecting Lantern
A magic-lantern which can be used for showing opaque objects is thus described: - On the inside of each end of the front, and on the inside of each end of the box, is a concave reflector; these are so placed as to concentrate the light upon the picture at the centre of the back of the box. In a tube F, projecting inward from the front, between the mirrors, is arranged a sliding tube G, holding a convex lens H. This tube is moved for focussing by means of a rod J extending up to the top of the back of the box. In the box two lamps or other lights - such as calcium or electric - are placed between the mirrors at each end, as shown in A Fig. 53. Above each light is placed a detachable funnel. The top of the box is curved and the under side is polished to reflect the rays of light. In the top is a ventilating opening provided with a hood to permit the hot air to escape; the supply of air is admitted through the perforated bottom. The pictures are held in a eliding apparatus moving between two longitudinal grooves B, secured on (he outside of the back of the box, and having two apertures, which can bo closed by hinged doors. The pictures are held in place by closing the doors, and can be shifted to appear in the opening in the back of the boi.
The light from the lamps is reflected by the mirrors upon the picture, and from the same through the lens upon a screen or wall. By means of a mirror T on a door S hinged to the front of the box below or at cither side of the tube, the light can be reflected upon any desired surface. Any opaque object, such as a photograph, chromo, or drawing, can easily be reflected upon the screen in any desired size, all parts being clear and distinct. The pictures do not become heated sufficiently to injure them, and may remain in the apparatus for hours without being destroyed. (Scient.
A "wonder contrived as to enable one to use opaque objects for projection upon the screen, instead of glass transparencies.
For example, if a photographer wishes ment from a carte will look, he simply has to put the carte in the "wonder camera and "throw it up." Many enlargement scales may be made in this way. Any photographer may make a. " wonder camera" for himself, and what follows will tell him how in a very simple wooden box with a top made of tin or sheet-iron; the chimney is made of the same material. The lens is the same as used upon a camera for making photographs. At the back of the box (as will be seen by reference to Fig. 53 A B C) are two doors placed upon hinges. When the box is in use the door e is kept closed. The other door consists of two parte placed at right angles to one another; the object of this is to All the opening in the door e while the pictures are being attached to e; when c is swung into position opposite the lens placed at b, d Is carried to one side. If stereoscopic views are to be shown, a slit may be cat at e, through which they-may be inserted without opening the box. The door e should be cut off a little at the bottom so as to admit air. The light is placed at h, as nearly opposite the picture as poasible. It should be a strong light; an argand burner is the beat. At the back of the light is a piece of tin bent into the form of a reflector. The light coming from h strikes e, and is reflected through the lens upon the screen. The plan of the box is represented with the top removed, Dimensions will depend upon the focal distance of the lens and height of the light.
Care most be tried to have the distance from the lens to c, when closed, equal to the focal distance. (T. Carter.)
A very compact form of magic lantern (Fig. 51) is adapted for all experimental purposes, as well as for the projection of views.
The best way to give acorrect idea will be to take, as example, a 4 1/2 in. condenser lantern, and give the dimensions of the different parts. The size of the condenser settles the question of the measurements of the other parts.
The two condenser lenses, plano-convex, are mounted each on a separate board. A circle is turned ont with a rabbet in each board, in which the condenser seats itself, and is secured therein by three buttons. The rear condenser board A is 6 3/4 in. square. The front board B is of the same width, but 8 1/4 in. long. To the rear one a strip is screwed across the top edge, and the front one is hinged to this strip. At their liases, coming between them, two small abutting strip are secured. The thickness of the strips is such that the boards, when brought together with the strips in contact, are strictly parallel, and the tenses are held apart from each other.