Home Fun

The vibration of the glass when emitting the notes explains this phenomenon, although the reason that the cross should remain still when you rub beneath one of its arms is too technical for explanation here.

A Light Experiment

Why do we wear white clothes in extreme heat and dark clothes in the winter? To this question every one will answer that white clothes absorb less heat than black, and that we therefore feel the rays of the sun less.

Quite true; and yet, how is it that Polar bears and other Arctic creatures exposed to such extreme cold are clothed in white?

The fact is that not only does white absorb less heat, but it serves to retain heat, and a white coat preserves the natural warmth in the animal’s body. This is exemplified by the following experiment, for which only a tumbler is required.

Choose a glass with the lower part faced, as in Fig. 12. Color these faces black and white alternately, a little India ink serving for the former and some crushed chalk and water for the latter.

With a very small knob of wax fasten a pin to each face, as shown in the figure. Having done this place a lighted candle within the glass.

The heat, striking the interior equally, is modified by the colors painted on the outside to such an extent that after some little while the wax supporting the pins of the BLACK faces is melted, whilst the pins on the white parts remain unaffected. This shows very clearly that the white prevents the escape of internal heat, as surely as it prevents the penetration of external warmth.

The Pyrometer

We all know that metals expand under heat. The amount of such expansion may be measured by a simple little apparatus called a pyrometer.

On a wooden base, B, C (Fig. 13), make two uprights, A and D, of which A must be a half inch higher than D. Bore a hole a quarter of an inch from the top of A, but not right through the wood.

A couple of pins must be bent into the shape of a Y and driven into the top of D, as in Fig. 13. With a little sealing-wax fasten a paper pointer to the eye end of a needle and lay the needle across the pins, P, P (Fig. 14). Next place an ordinary knitting-needle in the hole at A, and rest it over the small needle with the pointer. The pyrometer is now complete.

Put a lighted candle under the knitting-needle between D and A, as in the figure, taking care that the flame plays freely upon the needle. As the latter grows hot you will notice that the pointer moves slowly from left to right, being acted upon by the hot knitting-needle passing over the axle at X.

If a small paper dial be made against the pointer, the amount of the expansion can be even more clearly observed. Of course two or even more candles may be used, the result being that the needle shows more and more expansion as it becomes hotter.

The Broken Bottle

An interesting and useful experiment with a broken bottle is depicted in Fig. 15.

Fill the broken piece with oil to whatever level you desire it to be cut, and stand it upon a perfectly level table. Now plunge a red-hot poker into the oil and hold it there for a few seconds, when there will be a loud crack, and the top of the broken part will come off, even and smooth, as in Fig. 16.

It may not be generally known that a sheet of glass may be cut regularly and evenly with a pair of strong scissors.

A glance at Fig. 17 will give an idea of how this is done. The apparatus required is a large pail of cold water and a pair of strong scissors.

Plunge the glass, the scissors, and the hands, right into the water so that no part of either scissors or glass escapes immersion. You will now find that the scissors cut cleanly without the glass cracking or splintering.

The reason for this is that the water deadens the vibrations both of the scissors and the glass, thus insuring a neat and clean fracture.

Compressed Air

An interesting and effective experiment may be performed with compressed air. The arrangements are very simple and the requirements few.

Divide a walnut shell into two, and bore a hole in the bottom of each half. In one of the cups thus obtained make another hole half-way up the side, as in Fig. 18. Now, with a little sealing-wax fasten three straws into these holes.

In the cork of a fair-sized jar, which should be of some opaque glass, bore two holes, through which the straws must be placed at unequal heights, as shown in Fig. 19. Having almost filled the jar with clear water, place the cork with the straws so tightly that no air can possibly enter either at the sides or by any other means than through the straws.

The following strange effect will now be obtained. Pouring some colored liquid into the top shell A, plain clear water will come from the spout C of the lower shell B, and will continue as long as you pour from above (Fig. 20).

The reason of this is that the compressed air in the jar forces the clear water through the straw at B, which, being plunged deep into the clear liquid, carries off none of the colored matter passed into the jar by means of A.

This experiment may be performed with red wine and water, but the result is not quite so satisfactory on account of the ease with which wine and water mix.

CHAPTER XXXIX
MORE EXPERIMENTS
TIPS AND DODGES FOR THE WINTER EVENINGS

The Refractory Cork

A very interesting and amusing experiment may be performed with a bottle and a cork.

Take a cork of a diameter less than the internal diameter of the neck of the bottle you propose using, and ask a friend to make it enter the bottle by blowing upon it.

At first sight this seems a very easy task, and your friend at once proceeds to blow strongly upon the cork. This, however, instead of making the cork enter the bottle, causes it to fly out.

Again your friend tries to overcome the troublesome cork, on the next occasion by blowing very gently, but again it flies out (Fig. 1).

The explanation of this is as follows:—

In blowing upon the cork, a certain amount of air at the same time enters the bottle, the air in which becomes so compressed that it rapidly ejects the cork. There are, however, three ways in which the refractory cork may be overcome.

Since you know that by blowing on the cork it is at once ejected, try to achieve success by performing the contrary action—that is, by withdrawing some of the air from the bottle.

Indeed, the experiment will prove to you that, by so doing, you create in the bottle a partial vacuum, and as soon as your mouth leaves the neck of the bottle air enters it owing to atmospheric pressure. This incoming current of air pulls with it the cork, which at once slides into the aperture.

The same result may also be achieved by first warming the bottle, when, owing to the expansion of the air, a part of it is expelled. Directly the air inside the bottle cools, a vacuum is created, and a current of air from without enters. If you add to this current of air by blowing air from your mouth, you will find this quite sufficient to cause the cork to enter the bottle. Then, again, having a straw or a pipe-stem handy, all you have to do is to blow through the tube, directing the air exactly on the base of the cork, which will once again enter the aperture.

Whichever of these means is adopted, you must always take the precaution of seeing that the bottle is perfectly dry. It should be wiped every time. The moisture formed in the neck is sufficient to prevent the cork from gliding along the glass.

The Flying Coin

You may be inclined to think that special apparatus is necessary to make a coin fly from the bottom of a glass, but here is shown a very simple method by which the trick may be performed at any moment in your home.

First procure a liqueur glass of conical shape, having in its largest part a diameter not much greater than that of a silver dollar. At the bottom of this glass place a quarter, and above it, near the top of the glass, a silver dollar, the latter forming a kind of cover (A, Fig. 2). Now declare to your friends that, without touching the dollar, you will make the quarter jump from the glass.

This at first seems to them an impossibility, but all you have to do is to blow very strongly on the edge of the dollar. This will make the larger coin turn about on its own diameter into a vertical position, whilst the compressed air under the quarter causes the latter to fly out of the glass, after which the dollar returns to its original horizontal position.

A Cigarette-smoking Lamp-glass

This is a very striking experiment, and is quite easy to perform. The apparatus is also quite simple, and may be easily obtained. It consists of a lamp-chimney, a cork, a cigarette, together with two little valves.

Tightly cork up one end of the lamp-chimney with a large cork, thus hermetically sealing it. In this cork bore two holes, one following the line of the cork’s axis and having exactly the same diameter as the cigarette: the other being oblique with respect to this axis, and having a much smaller diameter (Fig. 3).

It is now necessary to make the valves. This is done by cutting from a glove two round pieces of the skin or leather, which, by means of pins, may be fixed over the holes, one being above the little hole on the top of the cork, the other over the large hole on the under side of the cork.

The first valve allows the smoke to escape, at the same time preventing the entrance of any external air, whilst the lower valve allows the smoke from the cigarette to enter the glass tube, but will not allow it to escape by the same hole.

Having thus made the valves, next plunge the tube in the water as far as the cork, and place the cigarette in the hole made for it. After having lit it, proceed to make the lamp-chimney smoke it.

In order that it may inhale the smoke, slowly raise the glass. By so doing a vacuum is produced between the surface of the water and the bottom of the cork. To destroy this vacuum, air must enter from without, and the only means of its entrance is through the cigarette, as the valve on the top of the cork remains tightly closed. In passing through the cigarette this current of air greatly assists combustion, and the smoke formed will pass with the air into the lamp-chimney.

If now the glass be lowered again, the air which is compressed by so doing closes the central valve, whilst that above the oblique tube is opened. From this valve the smoke will ascend in clouds (Fig. 4).

In this way the glass may be made to smoke the whole cigarette.

Water Swinging

Nearly every one has seen, at the circus or elsewhere, an acrobat executing giddy circular movements with a glass of water, and doubtless has wondered how it is that none of the liquid is spilt. This is due to the action of centrifugal force.

Having placed the glass full of water on the table, it is only a matter of taking it properly with the hand, holding it at arm’s length, and, with the arm thus extended, describing a complete circle, after which it may be placed upon the table without the loss of a single drop.

To insure the success of the experiment, particular attention must be paid to the manner in which the glass is held. Instead of taking it as you would when drinking, hold it with the hand reversed, the palm being turned upwards, as shown in Fig. 5.

Without hesitation throw the arm in the air, and swing it, not too quickly, but without shaking it, in the direction of the arrows in the diagram (Fig. 6).

After one complete revolution the glass should be as shown by Fig. 7; whilst in this position it may be placed on the table. At first it is advisable to practice this experiment with water, but, as more skill is acquired, other liquids, such as milk or wine, may be used as occasion permits.

A Novel Mirror

A simple method of illuminating the back of the mouth and throat, especially when throat trouble is suspected, may often be found extremely useful. Here is a means of supplying, at a moment’s notice, an extemporized illuminant of this kind.

Take a well-cleaned spoon, and hold it against a candle flame, when you form an excellent mirror, which will permit you to concentrate the rays of light and produce at the back of the throat enough illumination for the making of a careful examination (Fig. 8).

A silver spoon, moreover, allows you to study the curious properties of curved mirrors. Holding the hollow part of the spoon before your face, notice that the head is at the bottom; turn the spoon round, and you have the bulging part a convex mirror, which will show an image, very long and narrow. If you approach this face in the spoon little by little, you will see the nose attain the most amusing proportions.

A Disappearing Coin

If you look at an object which has been placed in water, owing to the phenomenon of refraction, the article appears in a different position from that in which it really is.

It is due to this phenomenon, therefore, that a stick, when half plunged into water, seems to be bent or broken.

A very interesting experiment based on this principle is the following:—

Take a bowl full of water, and at the bottom place a coin. Next request one of your friends to lower his head until his eye, the edge of the bowl, and the near edge of the cent, appear to be in the same line.

As a matter of fact, it is not the coin itself that your friend can see, but only the image created by refraction.

Now, keeping your friend in the same position, inform him that you intend to make the coin disappear from his view.

To do this, remove some of the water from the bowl, which may be accomplished by means of a small syringe (Fig. 9).

Directly you lower the level of the water, your friend will no longer be able to see the image of the coin, which will be hidden by the side of the bowl. If, however, the extracted water be replaced, the image of the coin immediately reappears.

Electrified Paper

Very few people realize that paper can be electrified at a moment’s notice, no special apparatus for the purpose being required.

Take a piece of light paper, which should have been well dried, and rub it briskly with a clothes brush, silk handkerchief, or even the open hand.

After a little time the paper, becoming electrified, will adhere to your face, your hands, or your clothes, as easily as if it were attached by means of gum.

Nor is this property confined to thin paper. Thick paper, when dried, will act in the same manner. For instance, take a postcard, dry it, and rub it, and you will notice that, as is the case with sealing-wax, glass, sulphur, &c., the card has the power of attracting light bodies, such as small pieces of cork.

The following interesting experiment may be carried out with an electrified postcard and a walking-stick.

Balance the walking-stick over the back of a chair, and announce that you can make the stick fall without touching it, without blowing it, or without interfering with the chair. This is easily possible by utilizing the electrified postcard.

First rub it on the sleeve of your coat. Now hold it near one end of the stick, and you will notice that the latter follows it as iron follows a magnet (Fig. 10), until the moment when the equilibrium being destroyed, the stick falls to the ground.

Of course the experiment may be varied by using any other suitable article in place of the stick, as for instance a fishing-rod.

Electrified Balloons

From the last experiment it may have been gathered that if a piece of paper is dried and rubbed with a silk handkerchief or the dry hand it will adhere to the face, arms, or clothing.

It may not be so widely known, however, that if toy balloons be filled with air, and then stroked for a short time with a piece of fur, they will act in the same way as the electrified paper.

It is rather amusing to see these balloons, after being treated thus, placed against the wall or ceiling, where they will stick as if they were glued there.

Having entertained your friends in this manner, you may, by way of a little change, take two of these toy balloons, and, after having electrified them, suspend them from the same point by means of two silken threads.

You will be surprised to find that the balloons now repel each other in the same manner as pith balls do (Fig. 11).

Exploding Flour

Flour will create an explosion!

Take a large handful of flour, and leave it for some time near the fire, in order that every trace of dampness may be expelled.

Whilst the flour is drying take a large tin box (a cracker tin will do admirably), and near the bottom make a small hole.

Through this hole pass the end of a piece of india-rubber tubing, and place the handful of dry flour in front of it.

At the other end of the box place a short piece of candle, and after lighting it, cover the box with the lid, taking care that it is not too firmly fixed.

If you now blow down the tube with your mouth, or better still, with a pair of bellows an explosion at once takes place, as a result of which the lid will be blown off (Fig. 12).

If flour be not available the experiment may be performed with equal success by using fine dust, such as may be found on the backs of pictures, or collected from any elevated parts of the room.

The Apparently Impossible

Have you ever had tea on the top of a mountain? If so, you will agree that your cup of tea could by no means be termed excellent.

Now, why is it that a cup of tea made on a mountain-top is much inferior to one made at a lower level? If the fault lay in the tea, the defect could be easily remedied, but such is not the case, for it depends upon the fact that water on the top of a mountain boils at a lower temperature than water at the sea-level.

In order to make a good cup of tea, the water must boil at a temperature very near 100° C., and it is at this temperature that the water is generally boiled in your homes.

Why is it, then, that water boils at different temperatures at different altitudes? It is because, as the altitude is increased, so the atmospheric pressure becomes less.

At sea-level, atmospheric pressure is equal to about 15 lbs. to the square inch, but at the top of a mountain it is much less. The greater the atmospheric pressure the more heat is required before the bubbles of vapor formed within the water can break at the surface.

After this explanation, perhaps the subjoined experiment will be attempted with additional interest.

Take a flask, to which should be fitted a good cork or india-rubber stopper, and in it boil some water, taking care of course to remove the stopper beforehand.

After some minutes the steam from the boiling water will have expelled all the air from the flask. Now remove the source of heat, at the same time quickly inserting the stopper.

If the flask is allowed to stand for a minute or two, the temperature of the water will fall considerably below 100° C.

Next inform your friends that, without applying any extra heat, you will cause the water in the flask to boil vigorously again. This seems to them impossible, especially when you tell them that you are going to do it by means of cold water. Quickly turn the glass upside down, and squeeze a sponge soaked in cold water on its upturned under-surface. Immediately the liquid inside will begin to boil, as if extra heat had been applied (Fig. 13).

But how are you to explain this apparently extraordinary phenomenon?

Well, directly the cold water comes in contact with the flask it causes the steam contained therein to condense, and, as no air can enter, thanks to the well-fitting cork, the pressure on the surface of the warm water is now considerably less than it was before.

Directly the pressure is lessened the vapor bubbles contained within the warm water are able to rise to the surface, and the water is seen to boil merrily.

Making Coal Gas

Here is a very simple way of obtaining coal gas.

Procure an ordinary long clay tobacco pipe, the bowl of which should be filled with very small pieces of coal. Carefully cover the top with soft clay, and put the bowl in the fire, with the long stem protruding through the bars. Now watch this end of the pipe very closely and see what happens.

Very soon you will notice a light-colored smoke issuing from the mouthpiece, but after a time this smoke disappears. But what happens if you hold a lighted match to the mouthpiece of the pipe? Immediately a bright yellow flame appears (Fig. 14).

The gas now burning is the same gas as is burnt in your house, although this latter, of course, is much purer.

If now you take the pipe from the fire, allow it to cool and then break it, you will be surprised to find that its contents have changed in appearance, for, in place of the coal, you will see what looks like a cinder. This is the coke. Thus you have manufactured gas from coal, at the same time producing coke.

Experiments with Carbonic Acid Gas

In a previous chapter, when describing how to make a miniature cannon, it was explained that the “gunpowder” with which the “shell” was fired is in reality carbonic acid gas.

It may not be amiss to show how to generate it, in order that you may discover for yourselves some of its properties.

There are several ways of obtaining carbonic acid gas, but most of these are of a complicated nature. The following, however, is an extremely simple method.

Take a 6-oz. or 8-oz. flask, and fit it with a cork with a hole, in which may be fitted a piece of glass tubing.

This tubing should be bent twice at right angles, as shown in Fig. 15, and the longer end should be allowed to dip into a large glass.

Into the flask pour a little lemonade, soda water or ginger ale, and after replacing the cork or tube, heat the flask by means of a gas-burner or spirit lamp.

You will notice that bubbles of gas are given off, and, as this gas is considerably heavier than air, it will, after being forced up the tube, displace the air in the glass, and gradually fill it. To test whether the glass is full, hold a match in the top. If the match is extinguished, the glass which is full may be removed. In this way several glasses can be filled, care being taken to cover each with a glass plate or cardboard disc to prevent diffusion.

From this experiment you will have discovered the three main properties of this gas (commonly known as carbon dioxide)—that it is colorless, is considerably heavier than air, and will not support combustion. Its high density affords another interesting experiment, which consists of pouring the gas from one glass to another (Fig. 16).

Take two glasses, one full of air and the other containing the carbonic acid gas, and into each plunge a lighted match. The match of course will burn in the glass containing air, whilst it will be immediately extinguished when it comes in contact with the carbon dioxide. You have thus clearly shown which glass contains air and which contains the gas. Now take the glass containing the gas and pour its contents into the other glass, in exactly the same way as you would pour in water. Again test with a lighted match and you will find that the gas has passed from one glass to another, thus proving that it is much heavier than air.

Next take two glasses, one containing air and the other carbonic acid gas, and, by means of a clay pipe, blow a soap bubble into each, carefully watching the different manners in which they behave. That dropped into the glass containing air will sink to the bottom, where, coming in contact with the glass, it will burst. The other bubble, however, as soon as it reaches the gas in the glass, rebounds owing to the high density of the carbon dioxide, but after a time, when it has settled down, it will float motionless on the surface (Fig. 17).

Before you finish experimenting you should know how to detect the presence of carbon dioxide. Take a little lime water, which may be obtained from any druggist, and pour it into a glass containing carbon dioxide. Shake the glass, and carefully observe the change which takes place. The lime water, which was previously colorless, has assumed a certain milkiness, and if allowed to stand the white powder causing this milkiness will settle at the bottom of the glass. This powder proves to be calcium carbonate, or chalk, which is always formed when lime water comes in contact with carbon dioxide, so that you have here a means of detecting the presence of carbon dioxide. Breathe into a little lime water and you will learn, from the milky appearance it at once assumes, that the air we exhale contains a certain quantity of this interesting gas.

CHAPTER XL
PHOTO PASTIMES

Camera Knights’ Experiments

It has been presumed in commencing these notes that most would-be experimenters already possess a camera, or will at least shortly do so. Thus the greater number of experiments are such as would interest a camera fiend more deeply than the ordinary reader, although the latter might still derive much enjoyment from conducting them so far as the lack of a “dark box” will allow him.

It will perhaps be as well to spend a paragraph at the outset in describing simply and noting a few peculiarities about the commonplace camera. Photography means drawing by the agency of light. Now light is reflected from an illuminated object in straight lines or rays, of which a proportion may be collected by a lens and thrown in points upon a surface behind. (See Fig. 1, A, illuminated object; B, lens; C, surface behind lens; D, rays of light thrown upon surface C.)

The front of a camera contains the lens, and is provided with a movable shutter, so that light may be only allowed to enter the dark box when a picture is to be taken on one of the sensitive plates inside. According to Fig. 2—which represents a camera in position to photograph the object A—the light is reflected in rays, which are collected in myriads of groups and cast pointed upon the surface of the sensitized plate B. Such ray groups—being parallel when they leave the object and pointed after passing the lens—are termed pencils of light, a most applicable name when they are employed in “sketching” a portrait on the photographic plate.

It will be seen that the action of the lens causes the base of the object to be registered upon the top of the plate, and vice versa—i.e. the picture is taken upside down. Another noticeable feature about the magazine box camera, which does not, however, apply to the focussing camera with bellows, is that it may not be placed nearer than a certain distance (usually 10 feet or thereabouts) to the object photographed, or else the picture obtained will be blurred. The remembrance of this simple fact will save the loss of many plates to the tyro.

Finally a last note remains to be taken of the “stops.” These are really various sized holes in a metal screen, any one of which may be placed at will before the lens, and by the use of which the sharpness or distinctness of the photograph may be improved. Thus a lens at full aperture will not give such a sharp picture as would be obtained if a small hole were used, but, as the amount of light permitted to pass in the latter case is much diminished, a longer exposure must be given. Consequently when a short-timed snapshot is being secured, the largest practicable aperture or stop should be employed, even though the sharpness of the picture be thereby to some extent sacrificed.

Having thus briefly reviewed the essential features of a camera, arrangements may be made for conducting our first experiment.

Experiment A.—A Fireside Photo

Probably no souvenir can give greater pleasure to the amateur photographer, or prove more acceptable to his bosom chums, than their portrait, as a fireside group, lighted by the glow from a genial fire. Nor is this difficult of attainment.

First the figures should be grouped seated on chairs—and perhaps some standing behind, if many faces are to be included—in a quarter circle from one chimney-corner, whilst the camera may be securely placed some 9 or 10 feet away, about the position shown at X in Fig. 3.

Next some shade like a small fire-screen must be placed between the blaze and the camera, in order to protect the sensitized plate from the full glare of the firelight. Now of course the photograph is not actually secured by the coal flame illumination, which would not be bright enough to give proper exposure, so recourse is had to dropping some material into the fire which will burn rapidly with a bright white flame. Magnesium powder is generally used for this purpose.

Supposing the group to have been arranged and the camera firmly in position, the person (B, in Fig. 3) seated next the grate should hold a tablespoonful of saltpeter and also a square inch or so of sheet zinc. Then, all being so far ready, let the outside member of the group (marked A in Fig. 3) open the camera shutter and slip back to his seat, whilst the flashlight operator drops the saltpeter and zinc successively among the glowing coals. The flame of dazzling brilliancy which results records the sitters’ figures on the plate, so that directly it is over, the person (A) may again visit the camera and close the shutter. His movements will not be noticeable, since they are made before and after the flashlight.

The operation of development may be proceeded with at once and should go fairly easily, but flashlight exposures are difficult to estimate accurately, and therefore, although a square inch of zinc has sufficed for a small group with stop and an extra rapid plate, this amount may have to be increased if the group be large or if other conditions be changed.

One last hint as to behavior of the sitters. Let them sit as naturally and quietly as possible, but be advised to blink their eyes as much as the bright light prompts them rather than keep them staring wide open, when their faces must wear a most inane expression in the finished photo.

Experiments B.—“Photo-Chemical”

Salts of silver form the basis of most modern photographic processes. Thus in order to perform chemical experiments of a photographic nature, some solution of silver must be available, the nitrate salt being usually employed.

It is best procured at the druggist’s in solution or as crystals, in which latter case it must be dissolved for use in clean rain or distilled water. The solution need be only weak, but must be kept in a dark bottle screened from daylight. Chemical test-tubes, if they can be obtained, will be found best for the experiments.

(1) Prepare a weak solution of table salt, and add it drop by drop to a little of the silver nitrate in a test tube (or wine-glass as a makeshift). A white sediment is precipitated, which, by shading part of the tube with a band of paper and exposing to daylight, may be shown to be sensitive to light, inasmuch as the unscreened part will rapidly turn purple. This precipitate consists of silver chloride, which, in combination with unaltered nitrate, forms the essential ingredient of printing paper. In Fig. 4, A is Solution; B, Precipitate; C, Band of Paper.

(2) Photographic plates are coated with bromide of silver, a yellow substance, which may be prepared similarly to the previous precipitate by adding potassium bromide solution (instead of table salt) to the nitrate of silver. Its appearance does not change rapidly under the influence of light, but if first exposed and then treated with a developing solution the yellow color very soon changes to black—finely divided metallic silver being, in fact, produced. Actually, light more readily alters the constitution of the bromide than that of the white chloride, but the former knows better how to preserve an outward appearance of composure.

(3) Suppose, now, another solution be made, this time of the fixing salt known familiarly to every camera knight as “Hypo.” When this is added to either the white chloride or yellow bromide precipitates above noticed, they gradually dissolve away, except such portions as have changed color under the influence of light.

Such action constitutes the process of fixing a photograph, whereby the sensitive silver compound is removed from those parts of the paper or plate which have more or less escaped the influence of light.

(4) This experiment is an aquatic performance in which one actor only—our old acquaintance Hypo—takes part. Provided proper care be taken in the preparatory stages, it will afford at the climax as excellent a spectacle as many another more complex.