Stories of Invention, Told by Inventors and their Friends Part 8

"Hence a wet rat cannot be killed by the exploding electrical bottle, when a dry rat may."

In a letter of 1750, based upon observations made in 1749, Franklin said distinctly, after describing some artificial lightning which he had made:--

"If these things are so, may not the knowledge of this power of points be of use to mankind, in preserving houses, churches, s.h.i.+ps, &c., from the stroke of lightning, by directing us to fix, on the highest parts of these edifices, upright rods of iron made sharp as a needle, and gilded to prevent rusting, and from the foot of those rods a wire down the outside of the building into the ground, or down round one of the shrouds of a s.h.i.+p, and down her side till it reaches the water? Would not these pointed rods probably draw the electrical fire silently out of a cloud before it came nigh enough to strike, and thereby secure us from that most sudden and terrible mischief?

"To determine the question whether the clouds that contain lightning are electrified or not, I would propose an experiment to be tried where it may be done conveniently. On the top of some high tower or steeple, place a kind of sentry-box, big enough to contain a man and an electrical stand. From the middle of the stand let an iron rod rise and pa.s.s bending out of the door and then upright twenty or thirty feet, pointed very sharp at the end. If the electrical stand be kept clean and dry, a man standing on it, when such clouds are pa.s.sing low, might be electrified and afford sparks, the rod drawing fire to him from a cloud.

If any danger to the man should be apprehended (though I think there would be none), let him stand on the floor of his box, and now and then bring near to the rod the loop of a wire that has one end fastened to the leads, he holding it by a wax handle; so the sparks, if the rod is electrified, will strike from the rod to the wire, and not affect him."

The Royal Society "did not think these papers worth printing"!

But, happily, Collinson printed them, and they went all over Europe. The demonstration of the lightning theory, which he had wrought out by his own experiments, was made in France, May 10, 1752; and in Philadelphia by Franklin with the kite in the next month, before he had heard of the success in France. Franklin's friend Dalibard tried the French experiment. Here is his account of it, as he sent it to the French Academy, as Roxana translated it for the young people:--

I have had perfect success in following out the course indicated by Mr.

Franklin.

I had set up at Marly-la-ville, situated six leagues from Paris, in a fine plain at a very elevated level, a round rod of iron, about an inch in diameter, forty feet long, and sharply pointed at its upper extremity. To secure greater fineness at the point, I had it armed with tempered steel, and then burnished, for want of gilding, so as to keep it from rusting; beside that, this iron rod is bent near its lower end into two acute but rounded angles; the first angle is two feet from the lower end, and the second takes a contrary direction at three feet from the first.

Wednesday, the 10th of May, 1752, between two and three in the afternoon, a man named Coiffier, an old dragoon, whom I had intrusted with making the observations in my absence, having heard rather a loud clap of thunder, hastened at once to the machine, took the phial with the wire, presented the loop of the wire to the rod, saw a small bright spark come from it, and heard it crackle. He then drew a second spark, brighter than the first and with a louder sound! He called his neighbors, and sent for the Prior. This gentleman hastened to the spot as fast as he could: the paris.h.i.+oners, seeing the haste of their priest, imagined that poor Coiffier had been killed by the thunder; the alarm was spread in the village; the hail-storm which began did not prevent the flock from following its shepherd. This honest priest approached the machine, and, seeing that there was no danger, went to work himself and drew strong sparks. The cloud from which the storm and hail came was no more than a quarter of an hour in pa.s.sing directly over our machine, and only this one thunder-clap was heard. As soon as the cloud had pa.s.sed, and no more sparks were drawn from the iron rod, the Prior of Marly sent off Monsieur Coiffier himself, to bring me the following letter, which he wrote in haste:--

I can now inform you, Sir, of what you are looking for. The experiment is completely successful. To-day, at twenty minutes past two, P. M., the thunder rolled directly over Marly; the clap was rather loud. The desire to oblige you, and my own curiosity, made me leave my arm-chair, where I was occupied in reading. I went to Coiffier's, who had already sent a child to me, whom I met on the way, to beg me to come. I redoubled my speed through a torrent of hail. When I arrived at the place where the bent rod was set up, I presented the wire, approaching it several times toward the rod. At the distance of an inch and a half, or about that, there came out of the rod a little column of bluish fire smelling of sulphur, which struck the loop of the wire with an extreme and rapid energy, and occasioned a sound like that which might be made by striking on the rod with a key. I repeated the experiment at least six times, in the s.p.a.ce of about four minutes, in the presence of several persons; and each experiment which I made lasted the s.p.a.ce of a _Pater_ and an _Ave_. I tried to go on; the action of the fire slackened little by little. I went nearer, and drew nothing more but a few sparks, and at last nothing appeared.

The thunder-clap which caused this event was followed by no other; it all ended in a great quant.i.ty of hail. I was so occupied with what I saw at the moment of the experiment, that, having been struck on the arm a little above my elbow, I cannot say whether it was in touching the wire or the rod, I was not even aware of the injury which the blow had given me at the moment when I received it; but as the pain continued, on my return home I uncovered my arm before Coiffier, and we perceived a bruised mark winding round the arm, like what a wire would have made if my bare flesh had been struck by it. As I was going back from Coiffier's house, I met Monsieur le Vicaire, Monsieur de Milly, and the schoolmaster, to whom I related what had just happened. They all three declared that they smelt an odor of sulphur, which struck them more as they approached me. I carried the same odor home with me, and my servants noticed it without my having said anything to them about it.

This, Monsieur, is an account given in haste, but simple and true, which I attest, and you may depend on my being ready to give evidence of this event on every opportunity. Coiffier was the first who made the experiment, and repeated it several times; it was only on account of what he had seen that he sent to ask me to come. If other witnesses than he and I are necessary, you will find them. Coiffier is in haste to set out.

I am, with respectful consideration, Monsieur,

Yours, &c., [Signed] RAULET, _Prior of Marly_.

MAY 10, 1752.

"I do not understand," said Uncle Fritz, "how it happened that no one attempted the experiment before. Franklin had proposed it, very distinctly, in 1750. His friend Dr. Stuber says that he was waiting for the erection of a steeple in Philadelphia. You see, the Quakers, who had founded this city, would have none; they derided what they called 'steeple-houses,' little foreseeing what advantage could be drawn from a steeple.

"Meanwhile, in 1750, in October, he did take a view of New York from the 'Dutch Church steeple,' which had been struck by lightning in the spring of that year. And here he was able to confirm his theory, by seeing that 'wire is a good conductor of lightning, as it is of electricity.'"

MUSICAL GLa.s.sES.

While some of the children were reading these electrical pa.s.sages, others were turning over the next volume; and to their great delight, they found a picture of the "Musical Gla.s.ses."

"I never had the slightest idea what musical gla.s.ses were," said Jack; and he spouted from Goldsmith the pa.s.sage from "The Vicar of Wakefield,"

where the fas.h.i.+onable ladies from London talked about "Shakspeare and the musical gla.s.ses."

"Were they Dr. Franklin's musical gla.s.ses?"

"I never thought of that," said Uncle Fritz, well pleased; "but I think it is so. John, look and see what year 'The Vicar of Wakefield' was written in."

John turned to the Cyclopaedia, and it proved that Goldsmith wrote that book in 1766.

"And you see," said Uncle Fritz, "that it was in 1762 that Franklin made his improvement, and that Mr. Puckeridge, the Irish gentleman, had arranged his gla.s.ses before. I think you would find that the instrument gradually worked its way into fas.h.i.+on,--slowly, as such things then did in England,--and that Goldsmith knew about Dr. Franklin's modification.

"I do not now remember any other place where Goldsmith's life and his touched. But they must have known a great many of the same people.

Franklin was all mixed up with the Grub Street people."

Meanwhile John was following up the matter in the Cyclopaedia. But he did not find "Armonica." Uncle Fritz bade him try in the "H" volume; and there, sure enough, was "Harmonica," with quite a little history of the invention. Mr. Puckeridge's fascinating name is there tamed down to Pochrich, probably by some German translator. Dr. Franklin's instrument is described, and the Cyclopaedia man adds:--

"From the effect which it was supposed to have upon the nervous system, it has been suggested that the fingers should not be allowed to come in immediate contact with the gla.s.ses, but that the tones should be produced by means of keys, as with a harpsichord. Such an instrument has been made, and called the '_harpsichord harmonica_.' But these experiments have not produced anything of much value. It is impossible that the delicacy, the swell, and the continuation of the tone should be carried to such perfection as in the simpler method. The harmonica, however much it excels all other instruments in the delicacy and duration of its tones, yet is confined to those of a soft and melancholy character and to slow, solemn movements, and can hardly be combined to advantage with other instruments. In accompanying the human voice it throws it into the shade; and in concerts the other instruments lose in effect, because so far inferior to it in tone. It is therefore best enjoyed by itself, and may produce a charming effect in certain romantic situations."

"'Romantic situations'! I should think so," said Mabel, laughing. "Is not that like the dear German man that wrote this? I see myself lugging my harmonica to the edge of the Kauterskill Falls."

"How do you know he was a German?" said Alice.

"Because, where John read 'the simpler method,' it says 'the before-mentioned method.' No Englishman or American in his senses ever said 'before-mentioned' if he could help himself."

"Do let us see how dear Dr. Franklin made his machine."

And the girls unfolded the old-fas.h.i.+oned picture, which is in the sixth volume of Sparks's Franklin, and read his description of it as he wrote it to Beccaria.

"Is it the Beccaria who did about capital punishment?" asked Fergus.

"No," Uncle Fritz said, "though they lived at the same time. They were not brothers. The capital-punishment man was the Marquis _of_ Beccaria, and that _of_ makes a great difference in Europe. This man 'did'

electricity, as you would say; and his name is plain Beccaria without any _of_."

Then Mabel, commanding silence, at last read the letter to Beccaria. And when she had done, Uncle Fritz said that he should think there might be many a boy or girl who could not buy a piano or what he profanely called a Yang-Yang,--by which he meant a reed organ,--who would like to make a harmonica. The letter, in a part not copied here, tells how to tune the gla.s.ses. And any one who lived near a gla.s.s-factory, and was on the good-natured side of a good workman, could have the gla.s.ses made without much expense.

_Letter of Franklin to J. B. Beccaria._

LONDON, July 13, 1762.

REVEREND SIR,--... Perhaps, however, it may be agreeable to you, as you live in a musical country, to have an account of the new instrument lately added here to the great number that charming science was already possessed of. As it is an instrument that seems peculiarly adapted to Italian music, especially that of the soft and plaintive kind, I will endeavor to give you such a description of it, and of the manner of constructing it, that you or any of your friends may be enabled to imitate it, if you incline so to do, without being at the expense and trouble I have been to bring it to its present perfection.

You have doubtless heard of the sweet tone that is drawn from a drinking-gla.s.s by pa.s.sing a wet finger round its brim. One Mr.

Puckeridge, a gentleman from Ireland, was the first who thought of playing tunes formed of these tones. He collected a number of gla.s.ses of different sizes, fixed them near each other on a table, tuned them by putting into them water more or less, as each note required. The tones were brought out by pa.s.sing his finger round their brims. He was unfortunately burned here, with his instrument, in a fire which consumed the house he lived in. Mr. E. Delaval, a most ingenious member of our Royal Society, made one in imitation of it, with a better form and choice of gla.s.ses, which was the first I saw or heard. Being charmed by the sweetness of its tones, and the music he produced from it, I wished only to see the gla.s.ses disposed in a more convenient form, and brought together in a narrower compa.s.s, so as to admit of a greater number of tones, and all within reach of hand to a person sitting before the instrument, which I accomplished, after various intermediate trials, and less commodious forms, both of gla.s.ses and construction, in the following manner.

The gla.s.ses are blown as nearly as possible in the form of hemispheres, having each an open neck or socket in the middle. The thickness of the gla.s.s near the brim about a tenth of an inch, or hardly quite so much, but thicker as it comes nearer the neck, which in the largest gla.s.ses is about an inch deep, and an inch and a half wide within, these dimensions lessening as the gla.s.ses themselves diminish in size, except that the neck of the smallest ought not to be shorter than half an inch. The largest gla.s.s is nine inches diameter, and the smallest three inches.

Between these two are twenty-three different sizes, differing from each other a quarter of an inch in diameter. To make a single instrument there should be at least six gla.s.ses blown of each size; and out of this number one may probably pick thirty-seven gla.s.ses (which are sufficient for three octaves with all the semitones) that will be each either the note one wants or a little sharper than that note, and all fitting so well into each other as to taper pretty regularly from the largest to the smallest. It is true there are not thirty-seven sizes, but it often happens that two of the same size differ a note or half-note in tone, by reason of a difference in thickness, and these may be placed one in the other without sensibly hurting the regularity of the taper form.

The gla.s.ses being thus turned, you are to be provided with a case for them, and a spindle on which they are to be fixed. My case is about three feet long, eleven inches every way wide at the biggest end; for it tapers all the way, to adapt it better to the conical figure of the set of gla.s.ses. This case opens in the middle of its height, and the upper part turns up by hinges fixed behind. The spindle, which is of hard iron, lies horizontally from end to end of the box within, exactly in the middle, and is made to turn on bra.s.s gudgeons at each end. It is round, an inch in diameter at the thickest end, and tapering to a quarter of an inch at the smallest. A square shank comes from its thickest end through the box, on which shank a wheel is fixed by a screw. This wheel serves as a fly to make the motion equable, when the spindle with the gla.s.ses is turned by the foot like a spinning-wheel.

My wheel is of mahogany, eighteen inches diameter, and pretty thick, so as to conceal near its circ.u.mference about twenty-five pounds of lead.

An ivory pin is fixed in the face of this wheel, and about four inches from the axis. Over the neck of this pin is put the loop of the string that comes up from the movable step to give it motion. The case stands on a neat frame with four legs.

To fix the gla.s.ses on the spindle, a cork is first to be fitted in each neck pretty tight, and projecting a little without the neck, that the neck of one may not touch the inside of another when put together, for that would make a jarring. These corks are to be perforated with holes of different diameters, so as to suit that part of the spindle on which they are to be fixed. When a gla.s.s is put on, by holding it stiffly between both hands, while another turns the spindle, it may be gradually brought to its place. But care must be taken that the hole be not too small, lest, in forcing it up, the neck should split; nor too large, lest the gla.s.s, not being firmly fixed, should turn or move on the spindle, so as to touch or jar against its neighboring gla.s.s. The gla.s.ses are thus placed one in another, the largest on the biggest end of the spindle, which is to the left hand; the neck of this gla.s.s is towards the wheel, and the next goes into it in the same position, only about an inch of its brim appearing beyond the brim of the first; thus proceeding, every gla.s.s when fixed shows about an inch of its brim (or three quarters of an inch, or half an inch, as they grow smaller) beyond the brim of the gla.s.s that contains it; and it is from these exposed parts of each gla.s.s that the tone is drawn, by laying a finger upon one of them as the spindle and gla.s.ses turn round.