MR TWADDLETON, on his arrival at the Lodge on the following morning, was informed that Miss Villers was expected at Overton in the evening.

"Your account of that young lady," observed the vicar, "has greatly prepossessed me in her favour; I only hope that she is not too blue."

"I care not how blue the stockings of a lady may be," said Mr Seymour, "provided her petticoats be long enough to hide them ;' and from my knowledge of Miss Villers, I can assure you, exalted as are her attainments, they are so veiled by feminine delicacy and reserve, that they may insidiously win, but will never extort our homage."

"Ay, ay," exclaimed the vicar; "I perfectly agree with you in your idea of feminine perfection-short tongues and long petticoats, Mr Seymour. But where are my little playmates?"

66

"I left Tom and Fanny on the terrace, a short time since, very busily engaged in the game of shuttlecock and battledoor." *

"The shuttlecock is an ancient sport," observed Mr Twaddleton. "It is represented in a manuscript as far back as the fourteenth century: and it became a fashionable game amongst grown persons in *SHUTTLECOCK, more correctly, per- | i.e., a striking-board. Thomson thinks haps, Shuttlecork, although Skinner that the true derivation is from the thinks it is called cock from its feathers. Spanish Batidor, a beater or striker, and Battledoor, so called from Door, taken that the game was introduced from the for a flat board; and battle for striking; Peninsula.

the reign of James the First. In China the shuttlecock is made of feathers and lead, and is played by being struck up by the soles of the feet. A toy of this kind may be seen in the Ethnological Room in the British Museum."

"It is a very healthy pastime,” said Mr Seymour, "and, in my opinion, is admirably calculated for females; for it expands the chest, while it creates a graceful pliancy of the limbs."

"I entirely agree with you; it is the only game with which I am acquainted, in which muscular exercise is gained without compromising gracefulness. But see, here come the two young rogues."

"I have been considering whether there is any philosophy in the game of shuttlecock," exclaimed Tom.

"There are two circumstances connected with its flight, which certainly will admit of explanation upon scientific principles; and I should much like to hear whether you can apply them for that purpose. The first is its spinning motion in the air; the second, the regularity with which its base of cork always presents itself to the battledoor; so that, after you have struck it, it turns round, and arrives at your sister's battledoor in a position to be again struck by her, and sent back to you."

"I perfectly understand what you mean; but I really am not able to explain the motions to which you allude," said Tom.

"The revolution of the shuttlecock about its axis entirely depends upon the impulse of the wind on the oblique surfaces of its feathers; so that it is often necessary to trim the feathers of a new shuttlecock, before it will spin."

"I understand you; the force of the wind, by striking the oblique feathers, is resolved into a perpendicular and parallel force, as you explained to us when we considered the action of the wind upon the kite."

66

Exactly; every oblique direction of a motion is the diagonal of a parallelogram, whose perpendicular and parallel directions are the two sides. Having settled this point, let us consider the second; viz., how it happens that the cork of the shuttlecock always presents itself to the battledore."

"I should think," said Tom, "that the cork points to the battle-. dore for the same reason that the weathercock always points to the wind."

66

Admirably illustrated!" exclaimed his father; "the cork will always go foremost, because the air must exert a greater force over the lighter feathers, and therefore retard their progress; but I must also direct your attention to the shape of the cork, which you may perceive to be conical, giving to the shuttlecock a readier passage through the air. Now this fact has an especial interest at the present time, from recent experiments showing the superior advantage of conical bullets

in rifles; but we will talk to the major about it.

While we are upon this subject, I will introduce to your notice some contrivances which are indebted to this same principle for their operation. In the first place, there is the arrow; can you tell me, Louisa, the use of the feathers which are placed round its extremity ?"

"To make its head proceed foremost in the air, by rendering its other end lighter, and therefore more sensible to the resistance of the air."

"Not exactly lighter,” said her father; "but rather by giving to that end of it an increased resistance to the air, by which its forward course is retarded: that is, unquestionably, one of the objects of the wings of an arrow; but there is also another, that of rifling it, or steadying its progressive motion, by causing it to revolve around its axis. If you will look at this arrow, you will perceive that the feathers are placed nearly, but not quite, in planes passing through it: if the feathers were exactly in this plane, the air could not strike against their surfaces when the arrow is in motion: but since they are not perfectly straight, but always a little aslant, the air necessarily strikes them as the arrow moves forward; by which force the feathers are turned round, and with them the arrow or reed; so that a motion is generated about its axis; and its velocity will increase with the obliquity of the feathers. You will therefore observe that, in order to enable the feathers to offer a necessary resistance to the air, they must possess a certain degree of stiffness or inflexibility. It was on this account that Roger Ascham,+ and other skilful artists in the days of archery, preferred the feathers of a goose of two or three years old, especially such as drop of themselves, for pluming the arrow; and the importance, as well as the theory of this choice, is confirmed by a curious observation of Gervase Markham, who says that 'the peacock feather was sometimes used at the short butt; yet seldom or ever did it keep the shaft either right or level!'" (47.)

"That is intelligible enough,” said Tom; "the feather of the peacock must have been so flexible as to have yielded to the slightest breath of air." Mr Seymour here observed that the Indians of the Amazon valley show their knowledge of the principle of rifling, in the way they feather their arrows. These feathers are generally from the wings of the macaw, and are secured spirally, so as to form a little screw on the base of the arrow, the effect of which is to make it revolve rapidly, and thus to keep it in a straight and direct course. Tom now requested that the action of the bow might be explained.

"I shall readily comply with your request before we part; but I am desirous, at present, of following up the subject before us, and of

* It would seem that the propelling force of the powder acts with greater advantage upon a bullet of conical form.

+ Toxoph. ed. 1571, folio 166. Markham's Art of Archerie, 1634.

N

taking into consideration some other instruments which owe their motions to the action of the air upon oblique surfaces."

"You will hardly venture," said the vicar, "to explain to them the action of the wind upon the sails of the mill."

"I should like to hear something about the windmill," observed Tom: "and perhaps Mr Twaddleton can tell us who invented the machine."

"The invention is not of very remote date. According to some authors, windmills were first used in France in the sixth century; while others maintain that they were brought to Europe in the time of the Crusades, and that they had long been employed in the East, where the scarcity of water precluded the application of that powerful agent to machinery."

“I had intended," said Mr Seymour, "to have entered very fully upon the subject of the windmill; for although it is a very common machine, its construction is much more ingenious than is generally imagined; it must also be allowed to have a degree of perfection to which few of the popular engines have yet arrived; but to do ample justice to my subject, I should require several models which are not yet in readiness; besides, Tom's holidays have nearly passed away : I must, therefore, postpone the examination of the mill to some future opportunity, and content myself, at present, with an explanation of its sails."

"And let me tell you," observed the vicar, "that, if you encounter this subject, you will commence a task little less heroic than that which engaged the prowess of Don Quixote, and one which has occupied years of mechanical research. The angle which the surface of the sails ought to make with their axis, in order that the wind may have the greatest effect, or the degree of weathering, as the millwrights call it, is a matter of nice inquiry, and has much engaged the thoughts of the mathematicians."

"My remarks upon that subject will be very general," said Mr Seymour; "I shall explain the principle, without entering into the minutiæ of its applications. The vertical windmill, which is the kind in most common use, consists, as you well know, of an axis, or shaft, placed in the direction of the wind, and usually inclining a little upwards from the horizontal line. At one end of this, four long arms, or yards, are fixed perpendicular to the axis, and across each other at right angles: these afford a surface, on which a cloth can be spread to receive the action of the wind. To conceive why these sails should revolve by the force of the wind, we must have recourse to the theory of compound motion. It is very evident that, if a mill exposed. directly to the wind should have its four sails perpendicular to the common axis in which they are fitted, they would receive the wind perpendicularly, an impulse which could only tend to overturn them;

there is a necessity, therefore, to have them obliqué to the common axis, that they may receive the wind obliquely, when their effort to recede from it causes them to turn round with the axis; and the four sails, being all made oblique in the same direction, thus unite their efforts for the common object."

"You have not yet told us what degree of obliquity the sail ought to make with the wind," said the vicar.

"The same as the kite ought to make-fifty-four degrees and forty-four minutes."

"Do you not remember, when we were last in London, you pointed out to us a curious mill on the banks of the river, which went without any sails?"

"You allude to the horizontal mill at Battersea."

"I remember it was at Battersea," observed Louisa; "and I dare say that you recollect the strange story which the waterman, who rowed us down the river, told Tom and myself. He said 'that, when the Emperor of Russia was in London, he took a fancy to the neat little church at Battersea, and determined to carry it off to Russia ; and that for this purpose he had sent a large packing-case; but, as the inhabitants refused to let the church be carried away, the case remained on the spot where it was deposited.""

"It is not a bad story," said her father; "for the mill certainly, both in size and figure, may be imagined to resemble a gigantic packing-case. The mill of which you are speaking has been taken down, in consequence of its use having been superseded by the introduction of steam. It was erected by Captain Hooper, who also built a similar one at Margate. It consisted of a circular wheel, having large boards or vanes fixed parallel to its axis, and arranged at equal distances from each other. Upon these vanes the wind could act, so as to blow the wheel round; but had it acted upon the vane at both sides of the wheel at once, it is evident that it could not have had any tendency to turn it round; hence, one side of the wheel was sheltered, while the other was submitted to the full action of the wind. For this purpose it was enclosed within a large cylindrical framework, furnished with doors or shutters, on all sides, to open at pleasure and admit the wind, or to shut and stop it. If all the shutters on one side were open, whilst all those on the opposite side were closed, the wind, acting with undiminished force on the vanes at one side, whilst the opposite vanes were under shelter, turned the mill round: but whenever the wind changed, the disposition of the blinds was altered, to admit the wind to strike upon the vanes of the wheel in the direction of a tangent to the circle in which they moved."

"Well; have you any other machine to explain to your scholars?" asked the vicar; "for I am anxious to present them with a bow and arrow which I have provided for their amusement."