CHAPTER XLIX.—ÆOLIAN HARPS, AND HOW TO MAKE THEM.
The simplest pattern of Æolian harp is that which fits into any ordinary window frame. A box of thin straight-grained, well-planed deal is glued together, having a length equal to that of the width of the window for which it is destined, a depth of four or five inches, and a breadth of five or six inches. The wood of which it is made is carefully planed on both sides, and is not over an eighth of an inch in thickness, and the joints are as true and clean as it is possible to make them. The more carefully this box is made the better will be the tone of the instrument.
The bridges in all Æolian harps are of some hard wood, such as oak, box, or elm, and are glued on to the face of the sounding-case. They are about half an inch high and a quarter of an inch thick. The strings are of catgut tightened by pegs screwed into the edges of the case, which are occasionally strengthened for the purpose by a thin fillet of beech. The strings are tuned in unison. Three inches above them is placed a thin board, supported on four pegs, one at each corner of the case. The harp is rested on the bottom of the window frame, and the sash is brought down on the upper board. The air passes in and out between it and the sounding-box, and the strings being set in vibration give off that soft, melodious murmur which, in a more subdued tone, is heard near telegraph posts when the wires are shaken by the wind.
Fig. 1.
This is the ordinary Æolian harp, but in this country and on the Continent there are many more complicated forms of the instrument in existence. The Æolians of the four Strasburg Cathedral towers, for instance, are well known to tourists. At the castle of Baden Baden also the harps are a great attraction, and we here give a [sketch] of one of the loudest of these celebrated instruments.
Fig. 2.
[Fig. 2 enlarged] (89 kB)
![[Fig. 2 enlarged]](#2320466686113905607_illo423alg.png.id-8094846119019186194.wrap-0.html.html){kind=link}
It is set well back in the gallery, and the window opening is gradually contracted by the curious shed, of which one side is removed to show the construction, the air passing out through the grating, which is only slightly wider than the harp. Of the harp itself we give the [plan and section], and to avoid fractions we retain its original measurement in mètres and centimètres—sixty-one centimètres being as nearly as possible two feet, and a mètre being a hundred centimètres, or thirty-nine inches and three-eighths.
It will be noticed that this pattern of the instrument has strings on both sides, and that the inner edge of the box is fitted with narrow sound-holes. The front of the box is of thin wood steamed into shape, and fitted round the curved ends as carefully as the sides are built into the back and belly of a violin.
Fig. 3.
In [Kircher’s harp], the older form, the screen fits into a window, the instrument is hung on an iron rod, and has a great many strings stretched over broad sound-holes. The case is freely perforated, and is hung so as to half overlap the aperture which gives admittance to the air.
Fig. 4.
Kircher for a long time had the credit of being the inventor of the Æolian harp, but it is of much earlier date. It is, in truth, a very obvious contrivance, easily made, and not susceptible of much improvement. In our last [figure] we give its latest form, which differs from the others only in the arrangement of the screens. These are devised to throw a strong draught on to the strings, without having to be fitted into a window frame; but in this, as in all the other forms of the wind harp, it requires a pretty strong breeze to bring out its full tone.
CHAPTER L.—THE PENNY WHISTLE, AND HOW TO PLAY IT.
By W. J. Gordon.
The best penny whistles are tuned in D, and we shall assume that ours is so. Occasionally, however, they are in a different key, but this does not alter the fingering, as the intervals are the same, and the same air will be played with the same stopping. There are six holes, which, commencing from the mouthpiece end, we will number 1, 2, 3, 4, 5, and 6. Of these holes, 1, 2, and 3 should be worked by the fingers of the left hand; 4, 5, and 6 by those of the right.
The lowest note of the instrument is sounded when all the holes are stopped—the reason, of course, being that the vibration takes place along its whole length. To get this note is, however, not easy, as there is a great tendency to blow too strongly, and so get into overtones. ‘The very gentlest breath will give the dulcet note we seek.’ Having got the D, and it must be a good full note, unstop 6, so as to keep only 1, 2, 3, 4, and 5 shut, and you will with the same strength of wind sound E, the note that comes just above it in the scale.
F-sharp, the next note, is got by unstopping 5 and 6; G, the next, by unstopping 4, 5, and 6; A, the next, by unstopping 3, 4, 5, and 6; B, the next, by unstopping 2, 3, 4, 5, and 6; C-sharp by unstopping all the holes.
Nothing can be easier of remembrance than this. The fingers are lifted from the holes one after the other, beginning at the bottom of the instrument, and with every finger you lift you rise to a higher note. But we have not quite finished the octave. How do you get the D? By leaving 1 open and closing the rest. And one note we passed, C-natural, how is that obtained? By unstopping 1, 5, and 6.
We have thus gone from D to D and got our first octave. How do we get the next? By blowing a little stronger, a very little, and unstopping on the same principle as before. Beginning with D, we have 1 unstopped, and then closing 1 and opening 6 we get E; opening 5 and 6 we get F-sharp; opening 4, 5, and 6 we get G; opening 3, 4, 5, and 6 we get A; and opening 2, 3, 4, 5, and 6 we get B, just as we did before, the fingering being the same, but the notes, owing to the stronger blowing, being an octave higher. The next note, C-natural, is obtained by unstopping 1 and 6; the next, C-sharp, is given by clearing 1, 5, and 6; the next, D, by clearing 1, 4, 5, and 6. And so we have completed our second octave. But we have four more notes yet that can be safely sounded without giving our audience the ear-ache, and of these E is got by unstopping 3 and 6, F-sharp by unstopping 2 and 5, G by unstopping 2, 4, 5, and 6, and A by unstopping 1 and 6. We thus have a range of twenty-one notes, including the two C-sharps and three F-sharps, so that our instrument is by no means a defective one, and the only difficulty in playing it is the avoidance of overtones where the artistic merit comes in at the middle D. It is, however, easy to remember that if you blow softly you get the lower octave, if you blow firmly you get the higher octave, if you blow wildly you get the peculiarly metallic screech which has made the penny whistle the abhorred of civilised men.
And now, having cleared the ground—for it is not our place here to teach the ‘rudiments of music,’ and in showing how to produce the notes we have gone as far as we need in a ‘monograph’ such as this—we will unfold the little scheme we had in view when we started on this description, and introduce to our readers the Boy’s Own Mechanical Penny Whistle!
The principle of the whistle, and, indeed, of all instruments of the flute and flageolet type, being that certain of the holes in different combinations should be left open in order to give the different notes, and that the expression should be given by the modulation of the wind strength, it follows that the fingering is merely mechanical. A substitute for the fingering can therefore be found, and the simplest substitute we have come across is a sheet of wrapping-paper!
Take a strip of brown paper or manilla paper, just wide enough to cover the holes on the whistle, or rather overlapping about half an inch on each side of the end holes. Mark off on the paper at each end of the strip where the centres of the holes come, and rule parallel lines the whole length of the paper, so that as it pulls over the whistle each of the six lines will pass exactly over the centre of each of the six holes. On each side of these six lines draw a line so that the space between the two new lines on each side of the central one may be half as wide again as the diameter of the hole across which it is to move.
Now rule the paper crossways in lines three-sixteenths of an inch apart parallel to each other, and strictly at right angles to the lengthway lines. The strip is now ready for you to stop out your tune on the principle of the Jacquard loom or the American organettes now so common amongst us.
Fig. 1.
First find the shortest note the air contains—in our example, the ‘Blue Bells of Scotland,’ this is a quaver—and each of the ruled spaces cut by the lines through the whistle-holes must represent this interval of sound. Double the space will give double the interval of sound, and hence, if one space represents a quaver, two spaces will represent a crotchet. In the Blue Bells the first note is D, a crotchet; and as D is produced by unstopping 1, we fill up on the first line a double space. The next note is G, a minim; and, as G is produced by unstopping 4, 5, and 6, we fill up space on those lines, making them double the length of the first space, the note being double as long. The third note is a crotchet, F-sharp, and this is marked by blacking in 5 and 6. There is no need to continue this explanation in detail, as the method is sufficiently clear, and the notes are given in [Fig. 1], and can be compared with the scale. One space equals a quaver, two spaces a crotchet, four a minim, in this instance; but should a quicker tune be selected the spaces may have to be given values of less interval. The simplest plan is to find the shortest note, and then, seeing how many of it would go to a bar, to mark off the bars along the edge of the scale, and then fill in at your ease. In our example eight spaces go to a bar, because the shortest note is a quaver, and eight quavers make the semibreve. Having filled in the notes, take a sheet of glass, lay the paper on it, and with a sharp penknife cut away all the spaces you have blacked—in short, make a stencil of your brown paper.
We are now ready to commence. Hang the stencil over the whistle so that the holes you have made in it pass over the whistle holes, and blow gently as you drag it along. As the holes are cleared one after the other the notes are given forth, and the whistle can be played almost as easily as a barrel-organ—if you can only keep the paper straight and flat on to the tin. But this is not always easy to do, and so we require a further invention, which the accompanying sketches sufficiently describe.
Fig. 2.
Fig. 3.
Fig. 4.
[Fig. 2] is a piece of deal, the shaded part of which shows where it is to be cut away. Two of these blocks, each of them about three inches long and two inches wide, are required. [Fig. 3] shows one of the blocks after it is in shape. The top groove in one must be larger and deeper than that in the other, owing to the tapering form of the whistle—for the whistle must fit firmly. Two rollers, made by sawing pieces off a broomstick, are taken of sufficient width to carry your stencil easily, and these are fixed as shown in [Fig. 4]. One has a handle made of bent wire, with the point that is driven into the roller flattened out and hammered in straight, so as to give a firm hold; the other has two spindles only.
The rollers are fitted with an elastic band, so as to keep them close together and make them act as a miniature mangle. A slip of wood is fastened beneath the blocks to keep them in position. If it is intended to play the air through only once, and to shift for each repetition, a weight is affixed to one end of the paper to keep it flat; if, however, the air is to be repeated without a pause, the ends of the stencil have simply to be pasted together, and a flanged roller hung in the loop, as shown in the cut.
This is all the contrivance consists of. It is effective, and easily made. The only difficulty in playing with it is the need of the stronger blow in the upper octave, a difficulty soon mastered after a little careful practice. The principle of the perforated keyboard is applicable to so many instruments that these rough notes on its construction may prove valuable, even if it be not applied to the humble whistle. The humble whistle! Alas! But let it not be imagined that squeals and screeches are the sounds the poor whistle was made to produce. Any other instrument, if improperly used, will give forth its appalling overtones. Treat it properly, gently, and firmly, and you will find it as sweet-toned as a flageolet.
SECTION IX.
ELECTRICITY, AND HOW TO USE IT IN PLAY AND EARNEST.
HOW VERY FUNNY!
CHAPTER LI.—CURIOSITIES OF ELECTRICITY.
By Dr. Arthur Stradling.
In the whole history of science, from the Dark Ages down to the present time, there has been no record of any parallel to the extraordinary progress which electricity has made of late years.
It is comparatively but a short time since that people were marvelling at the telegraph, and the newspapers used to write gushingly about ‘compelling the lightning to bear our messages,’ and all that sort of thing. I dare say many boys who read this can remember what a sensation the electric light made when displayed on the top of one of the buildings in the Strand—they need not be very old boys to have seen it there. Nobody would be very much attracted by such a light anywhere now.
There is scarcely a single art, manufacture, or science into which electricity has not been pressed to do good service. Electric lighting has become a matter of course, both indoors and out; and, while it has been proposed to annihilate night in the city of Washington by setting up four huge electric ‘suns’ on the hill of the Capitol, so rendering any other illumination in the streets and houses as unnecessary as in the day-time; a modified lamp of a few ‘candle-power’ has recently been devised for small rooms, supplied by a little battery which might stand on the mantel-piece. Tennis is played and photographs are taken by the electric light; electric bells are as common as door-knockers; electricity is proposed as a means of killing sheep and bullocks in the slaughter-house and criminals on the scaffold, and is used by the physician as a remedy for the preservation of life.
On board some of our great men-of-war the captain can sit in his cabin and not only see the position of the helm, the speed of the ship, and the direction in which she is steering, but can fire every gun she carries—all by electricity. Electricity springs the deadly mine on the field of battle, and animates a sixpenny toy sold in the Lowther Arcade. Even the railway engines, tram-cars, and screw-boats propelled by electric force which have been lately invented cause but little surprise now, so habituated have we become to the gigantic strides of this nineteenth-century infant!
I am not going to preach a sermon upon it, however, as you may be expecting from this terrific introduction; nor am I going to bore you with a lecture on coils and currents and poles and induction, or any other technical details. But it occurs to me that a brief mention of one or two of what may be termed the minor applications of electricity—one or two only out of thousands—will perhaps interest you, as illustrating how widely spread the influence of the science has become, and how it penetrates into nearly all the affairs of life. To my mind, the fact of telegraph and telephone wires stretching for hundreds of miles across uncleared jungles and through virgin forests, as they do, is not half so strong an evidence of the pitch to which it has arrived as its being adapted to a conjuring trick.
At one of the places of amusement in Paris some ‘sprites’ carry wands which sparkle out and fade again as required, flashing in time to the music. But a much prettier and more elaborate arrangement has been brought out since, though I believe it has not yet been presented to the public. The performer—magician, fairy, or whatever he or she may be—wears a fancy dress, which is embroidered all over with what look like large glass beads or imitation pearls. These are in reality tiny electric lamps, all connected with each other by wires covered with silk in the texture of the dress, and communicating with two little iron plates in the heels of the fairy’s boots. Nothing remarkable, of course, is seen until these two iron discs come into contact with a certain spot—which is reached just at the appropriate moment—when every bead bursts into dazzling light, and the fairy becomes clothed with white living fire in an instant! Then she steps away from the communication with the batteries below, and the beads are as suddenly dead again.
Electric alarums for the detection of burglars have long been in vogue in the shape of bells and gongs, so arranged as to be sounded directly the fastening of a door or window is tampered with, and electric ‘booby-traps’ have even been tried, designed to give the thief a severe shock or take him prisoner—the result generally being that the master of the house or the servants get caught in the snare themselves half-a-dozen times, after which its use is discontinued.
The weak point in all these things has been that, from their costly and intricate nature, they could not conveniently be applied to every accessible situation, and that the mechanism was always liable to be thrown out of order. The burglars would carefully avoid meddling with the shutters and doors to which these appliances were known to be affixed, and would gain an entrance at some unprotected spot. Now, however, somebody has patented an electric mat, which can be put down anywhere at night, and which sounds an alarm directly an intruder steps upon it.
Galvanism is employed, as is well known, by medical men, to restore power to paralysed limbs, to revive people who are faint almost to death, and to cure diseases. Dentists owe a good deal to electricity, and their patients owe still more. When a surgeon wants to cauterise some very small spot deep down in the flesh, instead of cutting and burning all the way down, he now inserts a wire, which is shielded, except just at the part which will come in contact with the bad place; an electric current is sent through it, and the wire becomes red-hot.
Neater still is the way in which a needle is detected underneath the skin. I dare say you know that such a thing often gives a doctor a great deal of trouble, and it is an accident which you should be very careful to guard against. It frequently occurs to boys who run about the house with bare feet. The needle, having no head like a pin to stop it, slips right into the flesh. Sometimes the patient is not certain whether it is there or not, as it may have worked out again, for the danger in these cases arises from the tendency of the needle to travel through the flesh, doing great mischief as it goes along. What is the doctor to do? If he is quite sure that it is there and can feel it, he will of course cut it out; but he has to be very cautious. A needle is so fine and slender, that sometimes, even when he thinks he can feel it with the point of a probe, he finds himself mistaken. It has been suggested that a magnet hung over the part will turn if any steel lie concealed beneath—a very pretty theory, but one that does not answer when put into practice. But one may make quite certain about it by probing the flesh with a little instrument which is connected with a battery in such a way that directly the point touches metal the circuit is completed and a bell rings.
Perhaps this was founded upon the very ingenious probe, by means of which the great French surgeon, Nélaton, discovered the bullet in Garibaldi’s foot. He could feel something there, at the bottom of the wound; but whether it was only the bone, or a bullet embedded in it, he could not say. So he made a slender probe of rough, unglazed porcelain, and rubbed it against the hard substance. On withdrawing it, he found it marked with lead!
Still more wonderful are the medical uses of the electric light. Not only is it made to illuminate the eye to the very back, but the throat as well. A little glass-bead lamp at the end of a rod is passed into the mouth, the current turned on, and there you can see the tonsils, gullet, windpipe and all, a great deal more distinctly than the interior of St. Paul’s Cathedral on a foggy day: while, to a bystander, the patient’s cheeks and throat look as if they were made of pink glass and filled with fire inside. Further, a similar rod and bead have been actually lowered into the stomach of a very thin person, and were found to be plainly visible through the semi-transparent skin; and it is thought that this may be valuable at times in the detection of disease.
From surgery to sleight-of-hand is a long step, but we find conjurers quite as eager to avail themselves of the assistance of electricity as doctors. Robert Houdin’s book on Magic gives an account of the marvellous adaptations of this science, wherewith his private house and park were furnished. He invented many of the tricks performed with electric apparatus by his successors at the present day—not such comparatively simple ones as ‘spirit-rapping’ hammers and drums which answer questions; but clever mysteries like the iron chest which a child can lift, yet which defies the strength of a man, and the crystal cash-box. These are things which might puzzle even scientific electricians who are not in the secret. By means of the first the great wizard acquired extraordinary influence over the Arabs in Algeria, because it seemed to them that he could at pleasure take away the strongest man’s power in a moment and cause him to become as weak as a baby, restoring it again as suddenly. It depends upon the fact that a current of electricity passed through a bar of soft iron makes it into a huge magnet for the time being. The little iron box, which is to be raised or remain immovable as the conjurer wills, is placed upon a pedestal, within which is the iron bar, connected with wires to a machine outside in charge of an assistant, who, at a given signal, turns on the current.
The crystal cash-box is a casket, the top, bottom, and sides of which are made of glass, bound with wire at the edges. No deception seems possible; it is transparent right through, and is suspended over the heads of the audience by four slender wires attached to little hooks at the corners; yet several half-crowns are seen and heard to fall down inside it at the word of command.
You will naturally guess that the entire affair is under the influence of a battery ‘behind the scenes.’ The coins are first concealed within a ground-glass ornamental design in the lid, the glass of which is double. The lower slip would be just loose enough to allow them to fall, but is kept up by a bit of black thread, which rests against the wire. Just at this point the wire is made of platinum, which becomes heated by electricity much more quickly than copper or iron, being a bad conductor. Almost the instant the current passes this bit of platinum becomes red-hot, while the connecting wires are not affected; the thread is burnt through, down drops the slip of glass, and the half-crowns fall or slide out with a jingle.
We know that by the telegraph wire we can read what people write hundreds of miles away, and can hear what they say through the telephone. At the time when all these ‘phones’ and ‘graphs’ were being invented, one after another, almost daily, an American paper announced another novelty—the telegastrograph! You were to hold one end of a wire in your mouth and taste the orange, plum-pudding, or glass of wine into which the other end was stuck a thousand miles off! But although this was a hoax, it would hardly have been more wonderful, had it been true, than many real facts among the curiosities of electricity.