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the cause of sensibility, irritability, and motion. Black venous blood, exposed to the air, becomes red on its surface; and air, remaining confined over venous blood, loses its oxygen, so that what remains is found to be unfit for combustion. These facts prove that the vermilion colour of the blood is owing to the inhalation of oxygen gas.

The internal surface of the lungs, or air-vessels, in man, is said to be equal to the external surface of the whole body: it is on this extended surface that the blood is exposed, through the medium of a thin pellicle, to the influence of the respired air. Well may the poet exclaim""Tis surely GOD

Whose unremitting energy pervades,
Adjusts, sustains, and agitates the whole.
He ceaseless works alone: and yet alone

Seems not to work: with such perfection framed
Is this complex stupendous scheme of things!"

1. From what work is this account of the apparatus for elaborating the blood taken ?

2. What simple idea can be given of the action of the blood? 3. How much blood is said to pass through the heart every hour? 4. What quantity of blood is supposed to be thrown out of the heart of a whale at one stroke ?

5. What is it that changes the dark colour of the blood to a bright red?

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The great Naval Victory at Copenhagen.

LORD NELSON, after a very severe engagement, on this day, 1801, gained a complete victory over the Danes, off Copenhagen, when eighteen sail of ships were either captured or destroyed. Our loss of men was considerable, besides the death of Captains Moss and Riou, two very brave and gallant officers, to whose memory monuments are erected in St. Paul's Cathedral.

The Emperor Paul had renewed the northern maritime confederacy, the immediate purpose of which was to set limits to the naval supremacy of England. A resolution being taken by the English cabinet to attempt its dissolution, a formidable fleet was fitted out for the north seas, under Sir Hyde Parker, in which Lord Nelson consented to go as second in command. Having shifted his flag to the St. George, of 98 guns, he sailed with the fleet in March, and on the 30th of that month he led the way

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through the Sound, which was passed without any loss. The harbour of Copenhagen now lay before them, defended by nineteen ships and floating batteries, flanked by extensive land batteries, on two islands called the Crowns, artificially raised for the protection of the port.

An attack being determined upon, the conduct of it was entrusted to Lord Nelson, with twelve ships of the line besides frigates. The combat which succeeded was one of the most terrible and best disputed upon record. It ended, however, after a conflict of five hours, by the striking of the whole line of Danish ships and floating batteries. Still the Crown batteries, and the ships at the entry of the arsenal, were untouched; while two ships of the assailants were aground, and others in hazard of a like fate. At this critical period, Lord Nelson, with the presence of mind of one familiarised to danger, sent a flag of truce proposing a cessation of hostilities, as otherwise he should be obliged to set on fire the batteries he had taken, without having it in his power to remove the brave defenders. The thought was, indeed, a happy one; for it put an end to further carnage; and on the landing of Lord Nelson to hold an amicable conference with the Prince-royal, the preliminaries of a treaty were arranged, which finally terminated the dispute. His great services in this expedition were rewarded by elevation to the dignity of a viscount.

1. What did Lord Nelson on this day, in 1801?

2. What was the object of the northern maritime confederacy?

3. What resolution was taken by the English Cabinet?

4. What proposition did Lord Nelson send to the Danes?

5. How were the services of Lord Nelson rewarded for his conduct in this expedition ?

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WITHIN a dungeon, mildew'd by the night,
Barr'd from salubrious air and cheering light,
Lo! the pale captive pines in hostile lands,
Chain'd to his doom by adamantine bands.
Oh! how he pants to face the fresh-wing'd breeze,
And list the voices of the summer trees:

To breathe, and live, and move, and be as free
As nature is, and man was made to be!

And when at night, upon his flinty bed,
Silent and sad, he lays his grief-worn head,
There, as the dungeon bell, with dismal sound,
Tolls midnight through the sleeping air around,
Remembrance wafts him to congenial climes,
And frames a fairy world of happier times.
The woodland haunts around his native scene,
The village dance upon the festive green,
His sloping garden where he loved to ply,
And smiled as peeping flower-buds hail'd his eye,
His beauteous partner and his blue-eyed boy,
Who prattled, play'd, and fed his soul with joy,
By thought created, crowd around his heart,
And force the pangs of fond regret to start;
Each dear delusion claims a parent sigh,
Each dream of happiness bedims his eye;
Till warm'd by Heaven, his home-wed bosom glows
With hopes that triumph o'er remember'd woes;
And far away the chainless spirit flies,

To vision'd realms of rest beyond the skies.

LESSON XCIV. APRIL THE FOURTH.

Queen Elizabeth.

On this day, in the year 1581, Queen Elizabeth dined at Deptford on board the Pelican, the ship in which Admiral Drake had circumnavigated the globe. The gallant seaman completed his task in two years, ten months, and twenty days. He was the first commander-in-chief who had performed this exploit; for Magellan died on his voyage, and his ship was brought round by Cano.

Drake brought home a large quantity of treasure, and his adventure became an interesting topic of discussion. The Spanish ambassador made complaints of him as a pirate, and reclaimed the plunder he had taken; and there were not wanting those who supported the same opinion, and thought that the nation would suffer more from the interruption of commerce with Spain, than it would benefit from prizes. On the other hand, many were elated with the reputation for valour and maritime skill which redounded to Englishmen for this enterprize, and thought that the injuries offered by the Spaniards to the traders in the West Indies justified reprisals. The court long wavered; at length, in the spring of 1581, the queen

OF SOUND, AND ITS VELOCITY.

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gave a sanction to Drake's conduct by dining on board of his ship at Deptford, and conferred upon him the honour of knighthood. The nation gladly joined in the applause. The commander's fame became a favourite theme, and verses were written to celebrate the ship which had "matched in race the chariot of the sun."

This celebrated vessel was afterwards broken up, and a chair, made out of the relics, was presented to the University of Oxford: upon which Cowley wrote the following

verses.

"To this great ship, which round the globe has run,
And match'd in race the chariot of the sun,
This Pythagorean ship, (for it may claim,
Without presumption, so deserved a name,
By knowledge once, and transformation now,)
In her new shape this sacred port allow.

Drake and his ship could not have wish'd, from fate,
A more bless'd station, or more bless'd estate;
For lo! a seat of endless rest is given

To her in Oxford, and to him in Heaven."

1. What did Queen Elizabeth on this day, in 1581?
2. How long did it take to complete Drake's undertaking?
3. Of what did the Spanish ambassador accuse Drake ?
4. What became of Drake's ship?

LESSON XCV. APRIL THE FIFTH.

Of Sound, and its Velocity.

THUNDER, the most awful sound in nature, is generally imagined to be produced by the clashing, or striking together, of two bodies of air; for the rapidity with which lightning darts through the air causes a vacuum, and the separated bodies of air rushing impetuously together produce that sudden report, or noise, which we call thunder. The same effect, only upon a smaller scale, is occasioned by setting fire to gunpowder. But gunpowder, dreadful and destructive as it is in air, when ignited in a vacuum, makes no more sound than the bell when struck by its clapper, in a similar situation.

The sounds produced by various metals differ widely as to their melody. The mixed metal of which bells are made is more sonorific than brass or copper; and these are more musical than several other sonoriferous substances. Now, all sonorific bodies are elastic, which being struck, their parts are made to vibrate; while these vibra

tions continue, correspondent ones are excited in the air, and these produce sound.

This doctrine is illustrated in the instances of bells, and the strings or chords of musical instruments; for notwithstanding the vibrations of the bell are not visible, yet if light particles of dust be upon its outside when the bell is struck, and you perceive them move, their motion ought to be received as a proof that the particles of the metal also move, though their vibratory motion cannot be perceived by the naked eye: and though the oscillation of a musical string continues some time after the sound ceases to be heard, yet it does not follow as a consequence that sound is not still produced, but only that it is not strong enough to excite a sensation in the ear. In a dark night you may see the flash of a gun, when the distance may be too great for you to hear the report. If, however, you knew that the light was occasioned by the letting off of a gun, you would conclude that it was attended with sound, though it was not strong enough to reach you.

The sound of the human voice, unassisted by any instrument, has been heard from New to Old Gibraltar, a distance rather exceeding ten miles; but the explosion or sound of hostile cannon has been heard 180, and even 200 miles from the place of action.

Sound is not, like lightning, conveyed instantaneously; it takes a certain time to pass through, or travel over, a given space. If you were half a mile distant from a party of soldiers, who, in performing the manual exercise, were firing at the word of command, you would see the flash or smoke before you heard the report of the muskets; but if you afterwards go close up to them, you would see the one, and hear the other at the same instant. The light of the flash and the report take place together. The former comes to the eye in an instant of time; the latter reaches the ear with the velocity that sound travels. If, then, light travels faster than sound, and if you are at any considerable distance from a gun discharged, you will see the flash before you hear the report.

Light travels at the amazing velocity of twelve millions of miles in a minute; its motion, therefore, in regard to a hundred yards, or as many miles, may be considered as instantaneous; seeing there would be no assignable difference of time to two observers, one of whom should be at the breech of the gun, and the other at fifty or a hundred miles from it; that distance being as nothing in comparison to twelve millions of miles.

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