DID you ever hear a siren whistle, - the kind that goes from a low note to a high note and then down again as it blows? Would you like to make one?

First take a paper roll - or maybe you haven't any. Well, then, roll some paper around a stick, a round stick, say a little over a quarter of an inch through or even half an inch. I made one once with a piece of broomstick to wind the paper around, and it worked fine, only my bellows wasn't quite strong enough to blow it well.

Put paste or glue on the paper and wind it around the stick, being careful that the stick doesn't get glued on, and hold the piece in a vise, or in some such way that it won't slip until it is dry. You can see how this is done in the drawings, Figure I.

After it is all dry, cut the notch n in the tube about an inch from one end. This is shown in my drawing of "Cutting the tube," Figure I.

Take out the stick and cut a piece from it an inch long as at a, the "wind block," and along one side cut off a thin slice, as at m.

Thus when you put the block back in the end of the tube, there will be a space 0 left between the tube and the block so that the wind can come up through it and out of the notch n that we cut. This wind block is shown at the bottom of the tube in the drawing "whistle section." It is shown at a in Figure 5. The tube we have made of paper is shown at W, Figure 1.

Now take the rest of the stick S and from it form a plunger G, or piston plug which will fit into the top part of the tube W and slide up and down. Since the paper was rolled around it, the plug will be a good fit and nearly air-tight.

Now put the whistle in your mouth and blow. If it does not whistle, the opening 0 cut from the wind block a is probably too small. Take the block out and cut off a larger slice. When it is all right, glue it firmly in place.

As the whistle blows, pull the piston plug in and out, and the note will vary like a true siren; with practice one can play a tune - whether it be music or not.

Then in a cigar-box cover at E, Figure 2, bore a half-inch hole. Under the hole glue a piece of thin leather V, with a piece of cardboard e fastened below to act as a stiffener or spring. These are glued along only one edge of the cover, so that the suction of the air can pull the leather down and let the air in, as in the sketch of the valve open, Figure 2, and then, when the air tries to go the other way, it will flop the leather up against the hole E again and close it. You see it must be fixed so that the air can go through one way and can't come back. Next fasten the cover down on the cigar box and paste up all the cracks with paper.

Then take a piece of half-inch board B, Figures 4 and 5, and cut it the shape of the box top, only an inch and a half shorter, and fix a similar valve in it the same way, Figure 5 - to let the air in but not out. Before you fasten this valve on, though, you must make the bellows' sides.

Take a piece of stiff Manila wrapping paper and fold it, as at A in the series on "folding the bellows," Figure 3. The folds should not be over three quarters of an inch wide, and the strip should be say three times as long as the side of the box that we are using for the wind chest.

Next, as at B, fold the paper at right angles so as to fit around the edges of the board B that makes the top of the bellows. Just fold it straight over and crease it hard.

When you straighten the strip out, you will find that the creases look like the parts a, b. Crease the folds b all the opposite way from what they now are, and the zigzag lines, too, down between a and the sides b; you will find that your corners are correctly turned, and will look as in the lower drawing of this series.

Lay this piece on the board B and cut off the ends so that the paper fits properly inside.

Over the sharp end of the wedge paste Manila paper piece c as in the drawing at the extreme right.

This makes the end air-tight. Paste the lower edges to the top of the box, and be careful to leave no gaps. Use liquid or fresh glue if you have it.

Smear glue on the upper flaps too, - that is, the upper edge of the paper bellows, - and press the board B down into position, holding it with a weight till dry. Be careful not to be anything but just the upper strip. Watch the corners too and glue all openings there.

At the right hand of B, in Figures 4. and 5, you see a black strip. This is a strip of leather running down under a wooden piece b, and which is glued to hold the lower edge of B secure, so it won't tear the paper.

SECTION SHOWING VALVES.

Put on the handle H, bore a hole in the box, as in Figure 5, glue in the whistle you have made, and the siren is ready.

When you lift H, - thus lifting B, - the air is sucked in through the valve in B, which opens. Then push down on B, and the air closes the valve in B but opens the one V in the cover of the box A, so that the wind rushes into the box and out through the whistle, with the expected result - a noise. So, by working the handle H up and down, the whistle blows.

If the bellows end tends to bulge out, paste paper or cardboard stiffeners at d, as shown.