Chapter XX: The Magic-Lantern, and All About It (2)

In cutting the tin for the next part, you must be careful to keep the sides and angles square; also in bending it into a tube and soldering it. Mark out on your tin plate (stout tin) a piece eleven and a quarter inches long and four and one-eighth inches wide, turn this into a tube by bringing the shortest edges together round a bottle, lap them a quarter of an inch, and solder the joint; now very carefully turn out one edge all round, one-eighth of an inch, being careful not to disturb the round. This can be done against the edge of a flat-iron by gently tapping with your small hammer. Cut out a circular piece of tin three inches and a half in diameter, and in the centre cut out a circular hole exactly the size of the small tube the lens-tube slides in; pass this tube half way through this hole, and solder it in, being careful that it is squarely in; now put this piece into the end of the large tube, not the turned-out end, so that the side that is soldered is inwards, and solder this on the inside of the tube. Next solder this tube, which is the nozzle of the lantern, on to the outside of the stage, being careful that the holes in the stage and tube correspond. You had better strengthen the stage by soldering corner pieces in where the turn-out parts are (Fig. 10). Now the stage and nozzle is ready to be screwed into its place on the front of the lantern, being careful that the centre of the holes are all in the same straight line; but before screwing it on, all the tin visible must be blackened with dull black paint, which I will tell you how to make at the end of this section. The inside of the lantern must also be painted with this black paint, as well as the inside of the front lens-tube. In this tube there must be what is called a diaphragm. To make this, take a piece of thin tin an inch and a quarter wide, and long enough to go round the inside of the lens-tube; solder the edges together, and close the end with a circular piece of tin with a circular hole in the middle of it a little less than half an inch in diameter. Blacken this and push it into the tube, so that the little hole is about half-way in. The lens-tube is to be pushed into the nozzle with the lens inside. To make the chimney, take a piece of tin six inches wide and nine inches and three-quarters long, bend it into a tube, and lap a full eighth of an inch; solder up the joint; then cut four notches in the top about three-quarters of an inch deep (Fig. 11).

Now mark on a piece of tin a circle four inches and a quarter radius, or eight and a half inches wide; cut this circle out. Now cut out a quarter of the circle (Fig. 12), bring the cut edges together, lap them a little, and solder the joint, so that it makes a small tin cone (Fig. 13). Put this on to the four points on the top of the chimney-tube, and solder those points into it securely, and your chimney will be finished and look like Fig. 14. This must be pushed into the hole at the top of the lantern.

Now for the lamp, and your lantern will be finished. You had better make this, as it would cost you 10_s._ 6_d._ to buy, and you have nearly all the materials required. Cut a piece of stout tin nine inches and three quarters long and three inches and three quarters broad; make it into a tube by joining the short edges together, lapping them a little, about an eighth of an inch, and soldering the joint. For the bottom cut a piece of tin round, the exact size to fit tightly into the tube; in the middle of this cut a circular hole three-quarters of an inch in diameter, solder this in the lamp so that it is half an inch from the bottom end, and then cut the half-inch that projects like you did the top of the chimney. Now make a tube of tin to fit the hole in the bottom, and long enough to come level with the top of the lamp; solder this up, and into its place in the lamp (Fig. 15). Next you must get a short piece of brass curtain-rod that will just fit tightly over this last tube and be the same length. In this brass tube you must cut a spiral slot, running from top to bottom, and going once round. The slot is to be cut quite through the brass (Fig. 16). The best way to do this is to cut a piece of wood, about eight inches long, and thick enough to fit very tightly in the brass tube; then with a sharp file make your cut. The cut is to be about one-sixteenth of an inch wide. Now push this brass tube on to the tube in the lamp, and fix it by pressing the brass in a little.

The next thing to make is the wick-carrier. Make a short tube of tin three-fourteenths of an inch long, and to fit easily over the brass tube; round the bottom of this short tube put a band of stout tin one-fourth of an inch wide; through this band drill a hole one-sixteenth of an inch, and solder a sixteenth-of-an-inch wire through it, so that it projects one-eighth of an inch inwards, and one-eighth of an inch outwards. This little wick-carrier must be notched with a penknife (Fig. 17), so that it is covered with little points directed downwards; these points are to catch in the wick and hold it firmly.

If this wick-carrier is put on the brass tube in the lamp, with the inside point in the spiral slot, as it descends it will turn to the left, and as it is lifted up it will turn to the right; consequently if it is turned to the right or left, it will ascend or descend, according to the way it is turned. To turn this wick-carrier we must have the following contrivance: Cut out a circular piece of stout tin that will fit easily into the lamp, and in the centre cut out a circular hole that will allow the wick-carrier to pass easily through it. At one side of this circular hole cut a little slot one-eighth of an inch each way (Fig. 18). Next make a tube of tin that will fit inside this hole, and will let the carrier pass freely up and down inside, but the edges of the tin must not be joined, but be an eighth of an inch apart. Solder this tube in its place in the circular tin, projecting through about a quarter of an inch, and so that the opening down the side of the tube corresponds with the square slot in the top. Solder a band of tin one-eighth of an inch wide all round the bottom of this tube to keep it firm (Fig. 19). Punch a hole in the top about a quarter of an inch from the edge, and fix a one-sixteenth wire in it about half an inch long.

Put this tube over the brass tube, so that the slot at top corresponds with the top of the spiral slot. Put the wick-carrier in its place, with the inner point in the spiral, and the outer point in the slot in the tube; and by turning the top to right or left the wick-carrier will ascend or descend, and, when the wick is fixed to it, will raise or lower the wick. To turn this top something more is wanted--that is, a movable top to carry the lamp-glass; this can be made to turn the movable top to raise the wick-carrier. For this you must get a piece of sheet-brass or copper--brass will look best, but copper is easiest worked. Whichever you decide upon, it must be a circular piece three and a half inches in diameter, and less than one-sixteenth of an inch thick. This copper is to be worked into the shape of a felt hat, with a crown three-quarters of an inch high, and one and a half wide. To do this you must make a block of hard oak wood six inches square and three inches thick; cut a hole in the middle the shape and size of the crown of the hat; this is to be like half a ball (Fig. 20).

Now make another block two inches thick and six inches square, and bore a hole in each corner to screw the two blocks together by with four-inch screws. Make a hole right through the top block one inch and a half wide. Now make your copper red-hot and chill it in cold water--this will soften it; put it on the lower block with the centre of the copper exactly over the centre of the hole in the block, place the top block on the copper, and screw the two blocks together as tightly as you can. Now make a piece of oak three and a half inches long, and one inch and three-eighths thick, into a roller, and round one end. Put the rounded end in the hole, resting on the copper, and strike it repeatedly with a heavy hammer or mallet. This will drive the copper into the hollow in the bottom block. You must make the copper soft by making it red-hot repeatedly, and you will find that it will be easily worked into the hollow. As soon as it is forced quite into the hollow in the lower block you must unscrew the two blocks and finish the fitting by hammering with a round-faced hammer. Your copper will now be like Fig. 21. Now you must file off the top of the crown, so as to make a hole at the top three-quarters of an inch in diameter, like Fig. 22.

Next you must cut the brim like Fig. 23, making three projections three-eighths of an inch wide, and three-quarters of an inch long. Now one-sixteenth of an inch from the crown of the hat bore a hole one-sixteenth of an inch at the end of each projection. Bend the outer end of each projecting arm a little less than a quarter of an inch downwards, till it is at right angles to the other part. Make a ring of thin tin three-eighths of inch wide, and one inch and five-eighths in diameter; cut the bottom edge away, leaving three projecting points one-sixteenth of an inch wide and a quarter of an inch long, equidistant from each other, put these projections through the little holes round the crown of the hat, and bend them inwards underneath. This will hold the ring tightly in its place. Now put this hat on the top of the lamp, and mark on one of the arms the place where the iron wire in the movable lower top comes, and then bore in that arm a hole one-eighth of an inch in diameter, and put the top on, passing the upright wire through this hole. Your top will now be like Fig. 24. The ring is to hold the chimney, and should have four or five slits in it a quarter of an inch deep, to clip the glass.

Now solder a handle to your lamp. Make a ring of tin a quarter of an inch wide, and one inch and a quarter in diameter, and solder the two ends to the lamp.

On the other side you must make the loop to hold the reflector. Take a piece of tin one inch wide and three inches long, and bend the ends at right angles to the middle, each end to be three-quarters of an inch long. Solder these ends to the front of the lamp. On the front of this piece of tin solder another an inch and a quarter long and three-quarters of an inch wide, soldering only the ends. This will be the loop to slip the hook on the back of the reflector in, and will keep it in its place. Your lamp is now quite finished, and will be as represented in Fig. 25. In fastening on this slip care must be taken to put it in such a position that when the reflector is in its place the centre of the reflector will be one inch higher than the top of the lamp, that is, the cut crown of the hat.

When using the lantern the lamp must be placed under the chimney, and pieces of board put under it to bring the centre of the reflector opposite the centre of the lens.

Now put a wick in. These wicks are circular, and about three inches and a half long. When buying them, take your wick-carrier with you to get the right size. They should fit tightly over this. These wicks can be bought at the lantern-shops, and are one shilling or one-and-sixpence a dozen. Put oil in your lamp, about two-thirds full. Light your lamp and put it in the lantern. Put the chimney on, put the lenses in their proper places, and try the lantern. If it gives a clear, sharp disc on the wall your lantern is all right, and ready to show the slides. If the disc is cloudy or has dark patches, move the lamp about till you get it clear. Move the front lens till the end of the disc is sharp.

You can paint your lantern all over with black paint. Brunswick black is the best to do this with. It makes the tin parts look nice. If you prefer it, and I think it is far the best, you can make your lantern of mahogany instead of deal, and polish it, and blacken the tin parts only. Mahogany board can be got for this very little dearer than deal. If you were to solder a brass-wire ring round the outside of the edge of the tube that carries the front lens, it would make it stronger and easier to regulate the focus, besides giving it a more finished look. If the nozzle and focusing-tube were made altogether of this brass plate it would add to the finish.

III. HOW TO MAKE THE SLIDES FOR A MAGIC LANTERN.

A magic lantern without slides is not of much use. These slides cost a good deal to buy, the price, ranging from two shillings to a guinea, being regulated by the time and skill expended in their production. In this section I will tell you how to make your own slides at a small outlay for materials. The time and skill you must supply yourselves.

The materials required are--a glass-cutter; some strips of patent plate-glass four inches wide--the glass of the thickness called eleven-ounce glass; thin black paper, crystal varnish, turpentine, tubes of water-colours, three or four sizes of sable-hair pencils; a good-sized camel-hair brush, with the hair cut straight off half-way down, for varnishing; some glue, two or three small dabbers made of fine linen or kid stuffed with wool, a palette, an easel, and a penknife.

The colours required are opaque black, warm brown, blue, dark green, yellow, and crimson. The palette can be made of a piece of glass six inches square, with a piece of white paper pasted on the back.

The easel you can make for yourselves. Fig. 1 will show how mine is made. A board twelve inches square and one inch thick forms the stand. To this, at about one inch from the front edge, is fastened by two hinges another smaller board, eight inches wide and eleven inches long from top to bottom, having a square hole six inches wide and nine inches long cut out of it, making it into a frame. This hole is filled with a plate of glass by glueing strips of wood all round inside the frame at the back for the glass to rest upon. The front surface of the glass must be flush with the front surface of the frame.

Up the front of both sides of the frame holes are bored about half an inch apart for the pegs in the shelf to fit into. This shelf is a piece of wood eight inches long and half an inch square. In the back of the shelf are fixed two iron pegs, which fit into the holes in the frame to keep the shelf in position. At each side of the frame is a wooden support screwed on to the outside by one end, so that it can be moved freely backwards or forwards, hinge fashion: the free end of each support fits into holes bored in the stand. By moving the supports backwards or forwards, and putting them in the holes in the stand, the easel can be lowered or raised at pleasure.

The upper surface of the stand is covered with white paper. You will require a hand-rest to keep the hand from touching the painting. This is made out of a piece of thin wood (cigar-box wood does nicely) eight inches long and one inch wide. To one side of this, at each end, glue a piece of the same wood one inch square, and in these pieces fix the iron pegs to fit into the holes in the frame of the easel.

When using the easel place it with its back to a window, or if you are painting by gas or lamp light place it so that there is a strong light on the white paper under the glass.

The glass to be painted is to be put on the glass of the easel resting on the shelf. When you have finished painting for the day you need not remove the picture from the easel if it is not finished, as by fixing the hand-rest over it and shutting down the easel you can cover the whole with a sheet of paper, and so protect it from dust. Now you have everything you want, and we will set to work at the painting.

First take your strips of glass, and with your glass-cutter cut them into pieces four inches square. Take one of these squares and well clean it on both sides. Put a little of each colour on your palette. Now place your glass over the design you wish to transfer to it, and very carefully go over the outline with your finest sable-hair pencil dipped into the opaque black moistened with a little water.

While this is drying mix in a small bottle some crystal varnish and turpentine in the proportion of one part varnish and two parts turpentine. When the outline is dry take it in your left hand, with the thumb on one edge and the fingers on the other. Dip the varnish brush into the varnish mixture, drain it partly on the mouth of the bottle, and carefully, with a light and free hand, go all over the glass, drawing the brush from top to bottom, beginning at the left-hand edge and working to the right.

Do not go over the varnish twice, or you may disturb the outline. Set the glass on one side to dry, but do not put it where it will get hot, or this may crack and streak the varnish.

While this is drying, take another glass, clean it, and trace outline of number two picture, varnish, and proceed with number three, and so on till you have six glasses outlined and varnished. It is better to have more than one picture to work upon at the same time; you do not then have to wait for the varnish to dry, as you can be colouring one while the other is drying.

When the varnish is dry, which will be in about a quarter of an hour, put one of the glasses, with the varnished side up, on to the easel, place the easel in a good light, and proceed to put in the colours. Put in the sky and background of the pictures first. The sky and all large surfaces must be put in as evenly as you can with the brush, and then you must go all over them with a fine dabber till you have got them perfectly even. In dabbing a surface such as a sky, do not mind dabbing the colour over other parts of the picture, as all the colour not wanted in it can be taken out with the moistened point of a brush before varnishing. When I paint my slides I sometimes purposely colour all over anything that projects into the sky, as I find I can get a more even surface by doing so.

When you have been all over the picture with the first coat of colour, varnish as before, and proceed with the second and third coats. You must be very careful in varnishing the colours, and not go over them twice. The colours are to be got at all artists’ colour shops. Ask for tubes of water-colours for glass-painting. Some of the larger firms also publish little books on glass-painting, in which you will find many useful hints.

When the colouring of the picture is finished, varnish it all over for the last time, and set on one side to dry. Now cut some squares out of your black paper the exact size of your glasses, and cut from the centre of each a circular hole three and a half inches in diameter; place one of these pieces on each of the varnished pictures (on the varnished side); take, and clean, six other glasses, and place one on each of the paper squares on the pictures; next fasten the two glasses together by glueing a narrow strip of paper all round the edges of each pair, and lapping on to each glass not more than one-eighth of an inch.

When they are quite dry your slides are ready for the lantern, and the pictures being inside between the two glasses, will be protected from injury from dust or scratches. In putting the slides into the lantern the painted glass should be nearest the light, if to be shown through a transparent screen; and the other glass nearest the light if to be shown on to a wall or opaque screen.

These slides will be too small to use in the lantern by themselves, so you will have to make a wooden slider for them. This is made as in Fig. 2.

Take two pieces of board one-eighth of an inch thick, four and a half inches wide, and eight inches long, with a square hole cut in each three and three-quarter inches square. These boards make the back and front of the slider, and are joined together at the top and bottom by two narrow strips of wood eight inches long, a quarter of an inch wide, and one-eighth of an inch thick. This slider is pushed into the slide-stage of the lantern, and the glass slides pushed into it as in Fig. 3.

The slider is rather smaller than the stage in the lantern, which allows of it being adjusted so that the centre of the picture is in a line with the centre of the lenses.

For making movable slides, such as slipping-slides, lever-slides, rack-slides, and chromatropes, you will require wooden frames.

To make these frames, get a carpenter to cut you some slips of pine or deal three or four feet long and half an inch square, with a groove running all along one side of each slip say one-eighth of an inch deep and one-sixteenth of an inch wide. Make your frames out of these slips of wood, seven inches long and four inches wide, outside measuring. Fit a glass in the groove like a slate is fitted in its frame.

Make about a dozen of these frames, and set them on one side to dry. Now cut some strips of glass three inches wide and seven inches long, and cut off one corner of each, as in Fig. 4, at any convenient angle, and then cut away the upper half of the front part of each frame flush with the glass, to allow the second glass to be pulled out about half an inch when put in position in the frame, as in Fig. 5.

Your frames are now ready to receive the design. Trace the design on the inside of the fixed glass with the effects; if it is to be a figure raising and lowering its arm, the figure must be drawn with three arms--viz., the arm that is not raised and the other arm in each position, one up and the other down, as in Fig. 6. The other glass has nothing on it but two black patches, one or the other of which covers one or the other of the arms as the glass is pulled out or pushed in.

In painting these slides, all the glass in the frame around the figures is to be blackened with the opaque black, so that all light is excluded except that which comes through the figures. When this slide is painted, varnish it and paste a narrow strip of paper on the top and bottom of the glass for the movable glass to slide on without scratching the picture.

The black patches on the movable glass are painted and varnished on the inside of the glass. To get these in the right place, place the glass in position over the picture, and when pushed in as far as it will go, mark with your black on the outside of the glass the outline of the arm that is to be covered in that position; then pull out the glass as far as it will go and mark in the same way the outline of the other arm; turn the glass over and fill in the outlines with opaque black, and on putting the glass in its place in the frame you will have a figure with its arms raised or lowered. Now put the glass in its place, and fix it there by pressing into the wood of the frame two small pins at the top and two at the bottom. In putting in these pins allow room for the glass to slide easily.

The construction of lever slides is something like that of the slipping slides, except that the movable glass is circular, and the picture on the glass in the frame is painted circular and has a background. The movable glass has painted on it only the limb that is to be moved. You can get these circular glasses cut at a glazier’s; have them three inches in diameter. Fig. 7 will explain how the two glasses are to be painted. By placing the movable glass over the fixed glass, and moving it partly round and back again, the two boys will appear to move up and down. Of course the point that the board hinges on must be in the centre of the picture. Before painting the picture, cut out a piece of thin board a quarter of an inch thick, three inches wide, and six inches long. Cut this in the shape of Fig. 8 (the dark part represents the wood). Glue this wood on to the glass inside the frame, and cut away the front edge of the frame down to the glass.

Now you can paint your picture, and while that is drying take one of your circular glasses and fit a rim--made of thin brass plate, a sixteenth of an inch thick--to it. This rim is to fit the glass tightly, and is to be a quarter of an inch wide; the ends are to lap a little, and are to be soldered together. Now cut from the same brass plate a strip two and a half inches long and a quarter of an inch wide, and solder this on to the rim, as in Fig. 9. Fix the circular glass in this rim, and on the inside paint the board and children on it, put it in its place in the circular hollow in the frame, and fasten it in its place with small pins pressed into the wood and bent over the brass rim (Fig. 10). By raising or lowering the lever the board will rock up or down.

Rack slides are very like the last description of slide, but in these the movable glass is capable of being moved quite round by a rack-and-pinion work.

IV. REVOLVING SLIDES FOR THE MAGIC-LANTERN, WITHOUT RACK-WORK.

BY F. CHASEMORE.

In my last section on magic-lantern slides, I mentioned that, although the frames for rack-work slides could be purchased, they were expensive. I have since then thought that the old-fashioned way of turning the revolving part--viz., by pulley and band--would be easy for boys to make, and answer very well if the cord is kept tight. In this section I give instructions in making these frames.

Make the outside frames five inches wide and ten inches long, out of wood half an inch by three-eighths, put edgeways. Cut a piece of thin deal or mahogany three-eighths of an inch thick and five inches square, and glue this on one side of half the frame (as Fig. 1). Cover the other half with a piece of glass four and a half inches square, and fasten it there with strips of deal, making them flush with the board on the other half. Glue corner-pieces (as in Fig. 4) on the other side of the glass, turning the frame over.

Make the circular frames out of a wooden circular box--such as a tooth-powder box--about four inches in diameter. Take off the lid and cut away the rim that it fits on, and saw the box into rings about a quarter of an inch wide, marking the box first with a pencil, and cutting through the marks with a fine saw (as Fig. 2). Have your circular glasses cut the exact size of the inside of these rings. Fix the glass in each ring so that the wood projects a trifle beyond the glass on one side. With a three-cornered file cut a triangular groove all round each ring about one-sixteenth of an inch deep.

Make the small wheel out of a cotton-reel about an inch or an inch and a quarter in diameter. Cut off the ends and cut the other part into slices a quarter of an inch wide, and cut a groove about an eighth of an inch deep all round each (as Fig. 3). On one side of each of these pieces fix a short wire about three-quarters of an inch long near the edge; this wire will serve as a handle to turn the wheel by. Fasten this small wheel to the board by a screw that fits easily into the hole in the centre, without too much play (Fig. 4). Put the circular glass and frame in its place and glue a piece of wood (A, Fig. 4), about two inches wide and a quarter of an inch thick, to the wooden half of frame. Get two small glass beads about a quarter of an inch long and an eighth of an inch wide. Put a wire about an inch long through each, and bend the wires as in Fig. 5. Sharpen the ends and press them into the edge of the wood (A, Fig. 4, B B), so that the beads will turn easily without touching the wood. Cut away a semicircular portion of the end of the frame (Fig. 4) and fasten a small button made of brass plate in it, and fasten another button to the wood (A). These buttons will keep the circular frame in its place. Connect the two wheels with a piece of strong twine, not too thick, going round them both, and fasten the ends by lapping them and sewing them together. Now if you turn the small wheel the large circular frame will turn round in the same direction if your work is well done. The edge of the circular frame must not touch anything but the glass it rests on, the two beads, and the two buttons. The view is painted on the inside of the fixed glass, and the revolving portion is painted on the under side of the circular glass. In Fig. 4 the mill and background are painted on the fixed glass, and the sails on the movable one.

Chromatropes can be made in the same way, except that the small wheel has two grooves in its edge, and the other part is made up of two revolving frames, which are turned in opposite directions by one cord passing round both and the small wheel. The lower frame rests on the square glass, and the other frame rests on the lower one. The cord is passed from the right-hand side of the lower groove in the small wheel up the right side of the lower frame, round the top and down the left side to the left side of the upper groove in small wheel, round the upper groove to right side up to the left side of upper frame, round the top down the right side of frame to left side of lower groove of small wheel, brought round, and the two ends joined. It will be seen that by putting the cord this way the two frames are turned in opposite directions, although the small wheel turns them both. Have the cord tight, and well rub all the parts that work together with blacklead.

In painting chromatropes, each glass is painted with the same pattern, and then they are placed face to face, and in turning make very elaborate and constantly-changing figures.

V. SCREEN FRAME FOR THE MAGIC-LANTERN.

BY FRANK CHASEMORE.

Great inconvenience is often caused in fixing a screen in a room for the lantern, such as taking down pictures, etc.; and sometimes it is impossible to hang it without doing some damage to the walls and paint by driving nails and hooks. Even then the screen has to be put up in an inconvenient place.

By using the following contrivance all this will be avoided. The screen can be put in any part of a room most suitable for the show, and afterwards taken to pieces in a few minutes and packed away in a box thirty-six inches long and about eight inches deep and wide.

The frame, or stand, can be bought at the shops, but it is much cheaper to make your own.

The materials for this frame can be bought at a small outlay, and are--fifteen wooden rods three feet six inches long and about an inch and a quarter in diameter--the handles sold at the shops for fitting to hair broom-heads do very well indeed, and are not very dear; two pieces of wood six inches long, five inches wide, and one inch and a quarter thick; and, lastly, some stout tin plate.

First of all, take the two wooden blocks and cut them the shape shown in Fig. 1; the width at top is three inches, and at the bottom five inches. Divide the top and bottom lines into two equal parts, and draw a line from top to bottom through the points of division. On this line mark a point an inch and a half from the top, and with this point as centre bore a hole right through the wood, which hole is to be just large enough for the wooden rods to fit tightly into. Draw a line across the face of the block half way down (as in Fig. 2). Along this line, and from each end of it, mark inwards a distance equal to the diameter of the wooden rods, and do the same along the bottom line (as in Fig. 2). Join these points as in the figure; cut out the middle portion, leaving the projections three inches long and an inch and a quarter square. These projections must be rounded by taking off the corners with a sharp chisel or knife. Trim them down till they are the same size as the rods.

Now you will want your fifteen wooden rods. See that they are all the same thickness. Cut off the ends of each, to make them quite square, and making the rods exactly three feet six inches long. From your tin plate cut fourteen pieces, each piece to be six inches long, and wide enough to go round the rods and to lap about a quarter of an inch. The width can be found by rolling paper round the rod and letting it lap a quarter of an inch, and then cutting it off. Place this paper on the tin and mark the width. The tin can be cut with a large pair of scissors. Now roll each piece of tin round the rods so as to form fourteen tubes. These tubes will now require to be soldered. You can get your tinman to do this for you, or you can do it yourself. If so, the following is the way to do it.

First of all, get some muriatic acid and some clean zinc cuttings. Put the zinc into a bottle and pour over it the acid, and set it on one side for a time till it has quite done effervescing; then add a little more zinc, and if it begins again wait a little longer and add more. Do this till it does not effervesce on putting new zinc into it, when it is ready for use. You must get some solder from the plumber’s, and if you have not a soldering-bit he will perhaps lend you one; but you can buy the bits now in many shops where they are sold on a card with some solder. The cost is from one shilling upwards.

The first thing to do is to ‘tin the bit’ (or cover the face and point with solder). This is done as follows. Place the bit in the fire to get hot, but not red. Take a clean piece of tin-plate and put on it a few drops of the zinc solution, and put a small piece of solder into it. When the bit is hot enough take it out of the fire, and with a coarse file clean the face and edges of it, and place it on the solder in the zinc solution on the piece of tin. In a few seconds the solder will melt and flow all over the point of the bit. This must be done to the bit every time it gets red-hot, as in that case the solder is burnt off.

Now put the bit back into the fire and take one of the tin tubes and first clean the surfaces that lap together by scraping them with a penknife. Rub each surface with the zinc solution and lap them together, and tie the tube round with string, to keep the edges in their places. Take the bit out of the fire when it is hot enough, and place it on the end of the stick of solder, which will be melted and stick to the bit. Place the bit on the top of the lapping edges, and in a few seconds the solder will flow from the bit between the surfaces to be joined, and by drawing the bit from one end to the other it will draw after it the solder and make a strong joint. If the bit did not at first carry enough solder to make the whole joint, more can be added by applying the stick of solder to the bit while it is on the joint. Solder the fourteen tubes, and clean off the joints by scraping and filing the superfluous solder off and polishing up with a piece of glass-paper. Clean the joint inside well with a piece of oiled rag to destroy the zinc solution left inside.

Now fit a tube on one end of each of fourteen of the wooden rods. The tube must be pushed on to the wood so that it is half way, or leaving an empty space of three inches. The tube can be fixed to the wood by two or three tacks driven through the tin. The fifteenth rod has no tube to it.

This is all there is to be made for the frame. In putting it together take the rod without a tube and two others, and join them together like a fishing rod, place each end of this compound rod into the hole in one of the blocks of wood, fit together the other rods into sets of three. There will be four of them. At one end of each set will be an empty tube, these are to be fitted on the pegs on the blocks at the ends of the other rod. The frame will now be composed of two uprights, each made up of two compound rods, and these support the cross rod or screen roller.

In the bottom rod of each set bore a hole with a gimlet, as in Fig. 3, and get two pieces of iron wire about one-quarter of an inch in diameter and bend the ends at right angles to the other part, leaving this middle part about two feet long. These are to be fitted to the rods, one to each pair, by pushing the bent ends into the holes in the ends of the rods as in Fig. 3; they are to be fitted on the outside of the rods.

Fasten these two wires together by passing a cord round both and tying the ends together. Sometimes the weight of the screen will cause the roller it is hung on to ‘sag’ or drop in the middle. But by tightening the cord underneath, the lower ends of the uprights will be brought towards each other, and will raise the middle of the screen roller.

To make the screen you must get some linen. This can be bought ten feet wide. Get three and a half yards of it, and have it hemmed at the top and bottom.

The top hem must be large enough for the roller to pass tightly through. The screen will get more or less creased in packing, but will come all right on being wetted and hung on the roller.

This frame is calculated for a ten-foot screen, which will be found large enough for most rooms. But it can be made for a larger one by adding one or more rods to each of the sets. The linen for a larger screen must be joined, as it is not made more than ten feet wide. In joining linen for this purpose do not let the seam come across the middle, but add an equal piece at the top and bottom, which will leave the middle of the picture clear, and the line of the join will come among the dark features of the foreground, and will not be seen so much. The tin tubes had better be varnished over with Brunswick black, as they will look better and not be liable to rust. Varnish the iron wires also.

In packing up, the screen must not be rolled on the rods, but had better be folded up by itself in paper and placed in the bottom of the box, and then the rods put in afterwards. Otherwise the screen might have some patches of Brunswick black in the middle of it.

Fig. 4 is a view of the screen and frame when put together.

VI. MAGIC-LANTERN FOR OPAQUE SLIDES.

BY W. J. GORDON.

A lantern to exhibit opaque slides or ordinary pictures on paper or cardboard is, if anything, easier to make than one of the usual type. It is nothing but a photographer’s camera with the action reversed. In the camera the large well-lighted object is focussed down by the lens into the miniature copy in the darkened box; in the lantern the miniature in the well-lighted box is focussed up into the enlarged copy in the darkened room.

The essentials are, a good lens, a good light, and a well-focussed, well-illuminated picture. Any ordinary box will do. Its shape and size are of little moment, but the box must be blacked inside and have the top replaced by or covered with tin or sheet-iron. Let it be, as we have to make one, say eighteen inches long and two feet high. The depth of the lantern depends on the focal length of the lens you have chosen for it. This lens can be either a plain magnifying-glass, such as is used in cheap lanterns of the common build, or it may be compound, of the sort used in portrait cameras. The compound lens will give the best results. Suppose we are dealing with a three-inch lens having a focal length of ten inches, our box should then be ten inches deep. Very much smaller boxes with less powerful lenses can of course be made, and they will act just as satisfactorily.

The top, as we have said, should be covered with tin, to prevent its catching fire, and it should be fitted with a chimney made by bending a sheet of tin and soldering its edges together. In order that a circle of light may not be thrown on to the ceiling, a cap must be fitted over the top so as to leave ample space for the passage of the heated air. In the front of the box a tube must be fitted, just large enough to hold another tube, in which the lens is held, and by this contrivance perfect adjustment of the focus is assured.

Arrange the interior as shown in the sketches, which are so numerous and self-explanatory that lengthened description is not required. The only peculiarity is in the back, which is so made to prevent a flood of light being thrown out behind each time a picture is changed. There are two doors to it, one being just a quarter the size of the other, and having a piece of wood of the same size fixed on at right angles of it, on the same principle as is seen in many mahogany birdcages where the inside flap of the seed or water-carrier just fills the hole made for the real door when the real door is open. The slide-carrier is marked A, and when the door is shut the marked side of the shade (B) fits close up against the side of the box. The lamp is placed as shown, and should be just far enough from the lens to thoroughly light up the picture without permitting itself to be seen. A paraffin lamp is the best, and it should if possible have a round argand wick; but a flat one will do fairly well. The round shape of the wick is suggested as giving in the majority of instances the most equable light. The bottom of the door should be cut away slightly or perforated, as in the sketch, so as to allow air to enter freely, as no lamp will burn without a draught.

It is a good plan to try the chimney on the top before the top is fixed on, and then if the top is left a little larger all round than will be required it can be shifted about until the proper position of the lamp with regard to the lens and slides can be found by experiment, and all risk of failure avoided. When the correct distance is found the top should be screwed down and trimmed to shape. Inside the box, below the chimney, a ring or stop should be screwed to prevent the lamp slipping about in the event of the lantern receiving a sudden knock.

In another form of this lantern the back is in one piece, and the slides are introduced through a slit at the side, a plan, however, having a few disadvantages. The principle of the opaque-slide lantern is apparent at a glance, and once that is understood no difficulty should arise in devising many patterns of the instrument and utilising old materials for the purpose. Any pictures can be shown, coloured or uncoloured; even our own designs in this book can be thrown on the screen with good effect.