With this stage and figures, a lad with a good voice and plenty of comicality will be able to give from half to an hour’s entertainment. When the performance is over, take the stage to pieces and pack it up, rolling it up in the curtains. It will go into a very small compass.
CHAPTER XLII.—HOW TO MAKE A PANTAGRAPH.
Take four flat sticks—size or material does not matter, but for an example let them be of deal—eighteen inches long, half an inch wide, and a quarter of an inch thick, and plane them up true and smooth. At an inch from the end of each stick make a dot, and divide the sixteen inches between the dots into inches, half inches, etc., as if the sticks were measuring rules. Using the dots as centres, bore in each stick a round hole just large enough to hold a piece of brass or other tubing whose internal diameter is that of a pocket pencil. Into one end of each stick fit a section of the tube, opening the edge as in eyeleting to prevent the quarter-inch ring so made from slipping out. Take a pair of the sticks, and hinge them together at the ends which have not been so treated with a piece of the tube—it will be about half an inch deep—eyeleting as before. Hinge the other pair together in the same way.
Now take a half-inch block of wood of any shape you please, but not more than two inches across; bevel it round its upper edge, and through its centre from the back drive an inch screw whose threaded part will just fit into the holes in the sticks. Screw it in till the head is flush with the bottom of the block. You now want a tracer or stile, for which take a similar screw, and cut off its head by filing the smooth part down to a gently tapering point. Slip the screw into the hinge of one of the couples, and keep it in its place by a leather washer above and below, making the distance between the under side of the wood and the point exactly that of the thickness of the block.
Now get half a dozen half-inch round-headed dresser-hooks, and put the apparatus together in the way shown in the [diagram], where B and C are the points at which your sticks are hinged. Slip one of the legs over the block F, and screw it down so that it will move freely but firmly with a leather washer. Place the leg (C D) under F B, and screw it into position from the upper surface with one of the dresser-hooks. Place the leg (C E) over A B, and screw that into place with another hook, also from above. The third hook is beneath the apparatus just close to B, the fourth beneath just close to A, and the fifth and sixth are used to screw the block on to the drawing-board, and are put in on the bevel, so that their heads will not project above the surface of the block. The tracer is screwed point downwards at C, the pencil is at A; and pencil-tracer, block, and hooks at A and B are all of equal length, so that the machine moves smoothly and evenly over the flat surface of your drawing-board.
Now place a map beneath the tracer, and a plain sheet of paper beneath the pencil. Hold the tracer with the right hand, the pencil with the left, and carefully guide the tracer over the outline of your map. Let the pencil move about as it pleases, and you will find that whatever the tracer does the pencil will mimic. The pencil will gradually draw a copy of the map, but it will move twice as fast as the tracer, and make its copy twice the size of the original. This is the result of the way we have at present arranged our pantagraph. The principle is that the copy compared with the original is always in the same proportion as the distance from the block to the pencil bears to that from the block to the tracer. Here the distance in a straight line from F to A is double that from F to C, hence the copy is double the size. The position of the tracer between the pencil and the block depends on the points in the sticks at which they are screwed together, and these you can vary to suit any scale you desire, remembering always that your figure (C G B H) must have its opposite sides equal—that is to say, C H must always equal G B, and C G must always equal B H.
To enlarge your map, the distance from F to C must be less than from F to A; to reduce your map the distance must somehow be greater. Hence you have only to transpose your pencil and tracer, putting the pencil at C and the tracer at A. To reverse the map, and keep it of the same size, put the block at C and the tracer at F. In short, by shifting about the pencil, block, and tracer in the different holes you will soon understand the curious properties of your new copying-machine. One thing do not forget, and that is that when you shift your pencil the hook which is put close by to steady its pressure on the paper should be moved with it.
The pantagraph, or pantograph, was invented by Christopher Scheiner two hundred and eighty years ago; and, carefully made of brass, is in many forms now used in architects’ and other offices where much drawing and copying are done. If not made quite truly its lines may be shaky, but it will be found invaluable for the accurate placing of points, to which lines can be afterwards filled in.