agined that, when the piston ascended, the water immediately rushed forward to prevent the occurrence of this much-dreaded vacuum. In the seventeenth century a pump was constructed at Florence, by which it was attempted to raise water from a well to a very considerable altitude, but it was found that no exertion of this machine could be made to raise it above thirty-two feet from its level. This unexpected embarrassment greatly puzzled the engineer, until Galileo suggested that the pressure on the water below must cause its ascent into the pump, and that, according to this theory, when it had risen thirty-two feet, its pressure became equivalent to that of the atmosphere, and could not, therefore, rise any higher; and as they did not, at that time, understand the construction of the piston-valve, the design was abandoned.

Before we quit this subject,” added Mr Seymour, "I wish to show you one or two experiments in farther elucidation of the effect of atmospheric pressure; but for this purpose we must return to the library."

As soon as the party had reassembled, Mr Seymour, pointing to the preparations on the table, said they would readily perceive that he required but a very simple apparatus for the occasion:- Here, for instance, is a common glass tumbler filled with water, and I place over its mouth a piece of paper. I now invert it, and you see the paper does not fall off, nor does a single drop of water escape from the glass. I ask you, Tom, for an explanation."

"I suppose," answered the boy, "that the pressure of the atmosphere upon the paper kept it in its place."

"Undoubtedly; the external pressure of the air was greater than the gravitating force of the water; and I trust that, after the late explanation of the pump, you will readily perceive that this difference in favour of the atmospheric pressure must continue as long as the column of water does not exceed thirty-two feet."

"I understand that perfectly; but still I do not exactly see why the paper cover was necessary to keep the water in the tumbler."

His father informed him that, from the ample expanse of its mouth, the water, without such a guard, would at once have gushed out, and been replaced by the ascending air; whereas, had the mouth of the vessel terminated in a narrow neck, the paper might have been easily dispensed with; since in that case the small column of water would be unable to force a passage for itself through the contracted orifice, without undergoing a dispersion, and to that the cohesion of its particles would oppose an insuperable obstacle.

"Have you never observed the difficulty of drinking out of a phial?" asked his father.

"To be sure; very often at school, but I was never before able to account for it."

L

"We will now proceed to another experiment. I have here a lampglass, converted for the occasion, as you may perceive, into a waterbottle, by means of a cork inserted into its lower opening. I now propose, as in my former experiment, to fill it with water, and to place over its mouth a piece of paper, and then to invert it as before -observe! not a single drop of water escapes."

"Why, that is nothing more than a repetition of your former experiment," exclaimed Louisa.

"You are impatient, my dear girl; let me beg that you will wait, and observe what will follow."

"See! I now make a hole in the cork with your bodkin, and away pours out the water, sweeping the paper before it like a cataract. Can you explain this?" asked Mr Seymour.

"I suppose," said Tom, "that the air, by rushing through the hole you made in the cork, pressed out the water by its weight, just as the pea was shot out of my pea-shooter."

"You have not answered my question with your accustomed consideration," said his father. "Let me ask you, how it is possible that the air thus admitted should possess any such power? Have you so far forgotten first principles as not to know that its internal pressure will be counterbalanced by the atmosphere on the exterior; and that, an equilibrium being thus obtained, we may exclude altogether the interfering influence of atmospheric pressure?"

"I see it all clearly now-by letting the air into the glass you equalized its pressure on the outside," said Tom.

And, therefore," added his father, "the water, being thus left to follow an unobstructed course, did, in obedience to the universal law of gravity, flow out of the vessel."

"With the knowledge, then, that you have thus acquired, you will readily understand many things of daily occurrence, which might otherwise appear unaccountable; thus, for instance, the vent-peg or spigot must be raised before the beer will flow out of the barrel. I allude more particularly to this example, as it will afford the simplest explanation of a very curious conjuring toy I have just obtained, and which I shall presently exhibit before you.”

The children, as may be readily supposed, were much delighted by so exciting an announcement; nor were the vicar and Major Snapwell less curious to learn the nature of the proposed exhibition.

Mr Seymour having rung the bell, a servant entered with a black pint bottle, and sundry small glasses, duly arranged on a waiter.— "I now propose to supply each of my guests, from the same magical bottle, with a glass of any wine he may call for," said Mr Seymour.

The vicar preferred port, and received it; the major required sherry, and his wish was gratified; Tom asked for some sweet wine, and he obtained it; and thus did Mr Seymour proceed, successively filling

five glasses, each with a different wine, from the same identical bottle.

"Bless my heart!" exclaimed the major; "I hope Mr Seymour has not formed an unholy alliance with the Prince of Darkness; for it must be confessed he rivals the magic of Mephistopheles in the wine-vaults of Leipsig.* At all events, let us beware how we spill a drop, lest it should turn to flame and consume us."

"Be not alarmed, my good and pious friends; as soon as I shall have described the ingenious construction of my bottle, its mysterious influence will be explained, and I shall be restored to your good opinion."

"This bottle," said Mr Seymour, "is made of tin-plate, so japanned as to resemble a common wine-bottle. In its interior there are five compartments, each terminating in a small tube in the neck, with an orifice on the outside. These air-holes, having a connection with the cavities within, act like the vent-peg of the barrel, to which I have lately alluded. When, therefore, they are covered by the fingers, it is evident that the liquid contents of the respective compartments cannot flow out of the bottle; but by raising each finger successively, we can command, at pleasure, the flow of any one of the liquids, in the manner you have witnessed."

Major Snapwell observed that he had frequently heard of this conjuring trick, as being one of the most surprising and successful efforts of M. Robin; whose wonderful art had lately elicited such general approbation from the sightseers of London.

We must now conclude the philosophic amusements of this day. To-morrow we hope to enter upon the interesting subject of the KITE.

*Goethe's "Faust."

CHAPTER XIV.

THE children were summoned into the library, and informed by their father that he was at leisure to explain the philosophy of the kite; a subject with which Tom had repeatedly expressed some impatience to become acquainted.

“It is a beautiful day," exclaimed the boy joyously; "and there is such a delightful breeze, that I should really call it a complete kite-day."

"Gently, my fine fellow," replied Mr Seymour: "the bird must be fledged ere it can fly. We have not, as yet, any kite; for you know that the one you possess is shattered beyond the possibility of repair."

"True; but could not Robert just step into the village and buy one? I saw several kites in the shop of Peg Robson yesterday."

“I do not doubt it, my boy; but the kites which are to be found in the toyshop are made to sell, rather than to fly; we must, therefore, construct one for ourselves; and see! I have accordingly prepared all the necessary materials for the purpose. I have here, as you perceive, a straight lath of deal, about three-quarters of an inch wide, and less than a quarter of an inch thick, and about four feet in length; this is quite ready for forming the standard, or back-bone of the kite: and now for the bow. The cooper has complied with my directions, and sent an unbent hoop as free as possible from knots; you observe that it is about the same length as the lath, but it will be necessary to pare it down a little at each end, in order to make it bend more readily to the required shape."

This having been accomplished, Mr Seymour proceeded to form the framework of the kite in the following manner. He first ascertained the central point of the bow, by balancing it on his fore-finger; he

then affixed that point, by means of string, to the lath at c, about an inch and a half from its upper extremity; a notch was next cut in each end of the hoop, or bow, a d; having fixed the string in the notch, a, he drew it through another, e, previously cut in the bottom of the lath, and carried it to the opposite end of the bow, d; the skeleton now presented the usual form of the kite. The next point, therefore, was to ascertain whether the two sides of the bow were in equilibrio, which he determined by balancing the lath on the finger, and observing whether it remained horizontal, or dipped on either side. This adjustment having been accomplished, Mr Seymour next continued the string from d across the skeleton to the opposite notch a, giving it one turn round the lath in its way; from a it was carried

to f, and wound round the top of the lath, and then again fastened at d; from d it was extended rather more than midway down the lath, and having been secured at b, was finally carried to, and secured in the notch a. The framework was now pronounced by Mr Seymour to be complete.*

The next part of the process was to cover it with paper. Mr Seymour observed, that the best kind which could be employed for this purpose was that known among stationers by the name of fanpaper, so called from its being manufactured for the use of the fanmaker; its merits, he said, depended upon the size of its sheets, as well as upon the thinness and firmness of its texture: this, however, was not at hand; he was, therefore, obliged to rest satisfied with its best substitute-viz., folio sheets of large thin post.

The party now went ding-dong" to work; paper, paste, and scissors were immediately put in requisition. Sheets of paper were laid smooth on the table, and so arranged that each sheet overlapped its neighbour about half an inch. The skeleton of the kite was then placed upon them, and the paper was cut to its figure; a margin, of about three-quarters of an inch, having been left around it, except

name of lining, has been found to be the best material as a covering for the kite. It is not only more durable than paper, defying the most boisterous wind, but superior to it as being secure from the effects of a shower of rain.

* The author has been thus minute, | monly known to haberdashers by the in order to afford his young friends clear directions for constructing a kite, and which, as far as he knows, are not to be found in any work hitherto published; and he will also avail himself of this opportunity to state, that the thin glazed linen of various colours, com