her danger?' He said, 'No; my Charlotte thought herself very ill, but not in danger. And she was so well but an hour and a half after the delivery!—And she said I should not leave her again—and I should sleep in that room—and she should have in the sofa bed—and she should have it where she liked—she herself would have it fixed. She was strong, and had so much courage, yet once she seemed to fear. You remember she was affected when you told her that you could not paint my picture just at that time; but she was much more affected when we were alone—and I told her I should sit when we went to Marlborough House after her confinement, 'Then,' she said, 'if you are to sit when you go to town, and after my confinement—then I may never see that picture.' My Charlotte felt she never should."

"More passed in our interview, but not much more—chiefly, my part in it. At parting he pressed my hand firmly—held it long, I could almost say affectionately, I had been, by all this conversation, so impressed with esteem for him, that an attempt to kiss his hand that grasped mine was resistless, but it was checked on both sides. I but bowed—and he drew my hand towards him: he then bade me good by, and on leaving the room turned back to give me a slow parting nod,—and though half blinded myself, I was struck with the exceeding paleness of his look across the room. His bodily health, its youthfulness cannot sink under this heaviest affliction! And his mind is rational; but when thus leaving the room, his tall dark figure, pale lace, and solemn manner, for the moment, looked a melancholy presage."

"I know that your good-nature will forgive my not answering your letter in detail, since I have refrained from it but to give you this narration of beings so estimable, so happy, and so parted."

"Prince Leopold's voice is of very fine tone, and gentle; and its articulation exceedingly clear, accurate, and impressive, without the slightest affectation. You know that sort of reasoning emphasis of manner with which the tongue conveys whatever deeply interests the mind. His 'My Charlotte!' is affecting; he does not pronounce it as 'Me Charlotte,' but very simply and evenly, 'My Charlotte.'"

NOTES OF A READER.

KNOWLEDGE FOR THE PEOPLE.

Part VII.—Mechanics.

We quote a few articles from the Introductory portion, illustrating the general principles of Mechanical agencies.

Why are we said to know of nothing which is absolutely at rest?

Because the earth is whirling round its axis, and round the sun; the sun is moving round his axis, and round the centre of gravity of the solar system; and, doubtless, round some more remote centre in the great universe, carrying all his planets and comets about his path. One of the grand laws of nature is, that all bodies persevere in their present state, whether of motion or rest, unless disturbed by some foreign power. Motion, therefore, once began, would be continued for ever, were it to meet with no interruption from external causes, such as the power of gravity, the resistance of the medium, &c. Dr. Arnott adduces several familiar illustrations of motions and forces. Thus, all falling and pressing bodies exhibit attraction in its simplest form. Repulsion is instanced in explosion, steam, the action of springs, &c. Explosion of gunpowder is repulsion among the particles when assuming the form of air. Steam, by the repulsion among its particles, moves the piston of the steam-engine. All elasticity, as seen in springs, collision, &c. belongs chiefly to repulsion. A spring is often, as it were, a reservoir of force, kept ready charged for a purpose; as when a gun-lock is cocked, a watch wound up, &c.

Why does a billiard ball stop when it strikes directly another ball of equal size, and the second ball proceed with the whole velocity which the first had?

Because the action which imparts the new motion is equal to the re-action which destroys the old. Although the transference of motion, in such a case, seems to be instantaneous, the change is really progressive, and is as follows:—The approaching ball, at a certain point of time, has just given half of its motion to the other equal ball; and if both were of soft clay, they would then proceed together with half the original velocity; but, as they are elastic, the touching parts at the moment supposed, are compressed like a spring between the balls; and by their expanding, and exerting force equally both ways, they double the velocity of the foremost ball, and destroy altogether the motion in the other.

Why does a walking stick help a man on a journey?

Because he pushes against the ground with the stick, which may be considered as compressing a spring between the earth and the end of his stick, which spring is therefore pushing up as much as he pushes down; and if, at the time, he were balanced in the scales of a weighing beam, he would find that he weighed just as much less as he were pressing with his stick.

Why is sea-sickness produced on shipboard?

Because man, strictly to maintain his perpendicularity, that is, to keep the centre of gravity always over the support of his body, requires standards of comparison, which he obtains chiefly by the perpendicularity or known position of things about him, as on land; but on shipboard, where the lines of the masts, windows, furniture, &c. are constantly changing, his standards of comparison are soon lost or disturbed. Hence, also, the reason why persons unaccustomed to the motion of a ship, often find relief by keeping their eyes directed to the fixed shore, where it is visible, or by lying on their backs, and shutting their eyes; and, on the other hand, the ill-effects of looking over the side of the vessel at the restless waves of the sea.

Why is the pendulum a time-keeper?

Because the times of the vibrations are very nearly equal, whether it be moving much or little; that is to say, whether the arc described by it be large or small. A common clock is merely a pendulum, with wheel-work attached to it, to record the number of the vibrations; and with a weight or spring, having force enough to counteract the retarding effects of friction and the resistance of the air. The wheels show how many swings or beats of the pendulum have taken place, because at every beat, a tooth of the last wheel is allowed to pass. Now, if this wheel has sixty teeth, as is common, it will just turn round once for sixty beats of the pendulum, or seconds; and a hand fixed on its axis, projecting through the dial-plate, will be the second hand of the clock. The other wheels are so connected with this first, and the numbers of the teeth on them so proportioned, that one turns sixty times slower than the first, to fit its axis to carry a minute hand; and another, by moving twelve times slower still, is fitted to carry an hour-hand.—Arnott.

Why do clocks denote the progress of time?

Because they count the oscillations of a pendulum; and by that peculiar property of the pendulum, that one vibration commences exactly where the last terminates, no part of time is lost or gained in the juxtaposition (or putting together) of the units so counted, so that the precise fractional part of a day can be ascertained, which each such unit measures. The origin of the pendulum is traced to Galileo's observation of a hanging lamp in a church at Pisa continuing to vibrate long and with singular uniformity, after any accidental cause of disturbance. Hence he was led to investigate the laws of the phenomenon, and out of what, in some shape or other, had been before men's eyes from the beginning of the world, his powerful genius extracted the most important results. The invention of pendulum clocks took place about the middle of the seventeenth century; and the honour of the discovery is disputed between Galileo and Huygens.