OF SOUNDS.

417

1836.] when the roots are most active in feeding and lengthening out. To spread out manure in dry weather, or bright sunshine, must be to certain loss; to wheel it out in winter, and leave it in heaps, is bad, from giving too much to the spot where the heap is.

Rennie's Alphabet of Gardening.

In our last number (p. 392,) we spoke of the doctrine of "sounds," and mentioned a few examples to show that sound was occasioned by vibration; that when an impulse was given to the air, there was a motion like that of water when a stone is thrown into it; and that the waves of air enter the ear and strike on the tympanum (or drum) of the ear, and that a sensation of sound is thence conveyed to the brain; that elastic bodies by their vibration render a sound, and that sound is conducted by means of solid bodies. But it is likewise true that sound is not only conducted through such bodies, but that its velocity is increased in passing along them (it moves faster). For instance, sound is propagated more rapidly through water than through air. "It is calculated that an impulse of sound would pass through fresh water four times as fast as through air, and through seawater one seventeenth faster still; whence it may be shown, that a commotion sufficiently violent might be propagated from one pole of the earth to the other in 200 minutes. From this consideration we may account for the swell of the sea observed before a storm,-the impulse given to the water at a great distance being communicated much more rapidly than the motion of the wind, which therefore arrives later. The shocks of the earthquake at Lisbon in 1755, were propagated through the waters of the ocean, and felt as far as the East In dies. Ice propagates sound; it is said that in the frozen regions of Tartary the people lay their ears close to the ground, and that they can thus distinguish the approach of cavalry at a very great distance. Sound moves uniformly; that is, it moves through equal spaces in equal

times. It is propagated through iron ten and a half times as fast as through air.

Echoes arise from the reflection of sound from any object against which it strikes. Caverns, rocks, and grottoes return an echo; so does the surface of a wall. In the lake of Killarney in Ireland, and in the Peak of Derbyshire, are wonderful echoes; buildings of an oval or a circular form are more adapted than others for the propagation of the sound. A speaking trumpet is a tube to which a mouth-piece is attached; and a person holding his mouth to it, and speaking through it, is heard at much greater distance; this is caused by the air being kept within the tube, none of it escapes through the sides; thus there are more of the waves of air sent towards the hearer. This instrument is used much at sea, when there is need of giving orders from one ship or boat to another, when the distance and noise of the sea would prevent the natural voice from being heard.-Chiefly from Mitchell's Text-Book of General Knowledge.

BRENTWOOD SOCIETY FOR ENCOURAGING THE OBSERVANCE OF THE SABBATH.

OUR number for last month (p. 390) recorded the praiseworthy exertions of several gentlemen at Brentwood for the better observance of the sabbath-day. Even if it should appear that no great good can be done by parliamentary interference, yet a great deal of good will be done by the exertions of right-minded and pious individuals, not only by the regulations which they may encourage in their neighbourhood, but by their own examples and by the habits which they adopt in their own families; and we shall rejoice to hear that the example of the inhabitants of Brentwood is followed in other parishes. The first rule of the Brentwood association is to change the practice of paying labourers on a Saturday or Sunday. The practice of paying on a Sunday is so bad, that no one of right views would ever think of it; and paying on a Saturday-night produces almost as bad an effect, for it is generally too late for the labourer

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CAUTION TO BLACKSMITHS.

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to go to market, so that he is led to go to the shop on the Sunday-morning; and he too often, moreover, spends a part of his money at the ale-house on the Saturdaynight. The second rule is of great use, which pledges the members of the society to check the practice of tradesmen sending home goods on the Sabbath-morning. This ought to be a rule in every family; no goods should be taken in. Many tradesmen and their messengers lose their Sabbath opportunity of rest as well as of public worship by being required to forward their goods to their customers on the Sunday-morning. The dinners from the bakers are excepted from this rule. There is something to be said in favour of this exception, as many families may have the opportunity of going to church by having their dinners sent to the public oven. We should, however, be glad to see the bakers have their sabbath of worship and of rest as well as other people; and we expect that this will be brought about in time, as we see that in families where religion is the first consideration, the business of dinner is contrived without hindering bakers or any one else from attending public worship. We shall not attempt to go through all the rules of this society, but are glad of this opportunity of calling the attention of our readers to the subject, and we trust that they will all join in the spirit of the last rule,-" that every member of this society endeavour to do his utmost in his parish and neighbourhood to promote the reverence of the Lord's day both by precept and example."

CAUTION TO BLACKSMITHS.

V.

By the General Turnpike Act, 3d Geo. IV. c. 126, every blacksmith occupying a blacksmith's shop situate near a turnpike road, and having a window or windows fronting the said road, who shall not, by good and closed shutters, every evening after it becomes twilight, bar and prevent the light from such shop shining into or upon the said road, is liable to a penalty of 40s. over and above any damage occasioned thereby, which may be recovered before any Justice of the Peace where the offence is committed.

THE most noble building in London is St. Paul's Church. As soon as London is seen at a distance, this Church is the principal object. It is built in the form of a cross, with a stately dome in the centre. Its length on the outside, including the portico, is 510 feet, and its breadth 282; the height to the top of the cross is 404. This Cathedral was built at the national expense, and cost 736,7521. It was thirty-five years in building; the first stone being laid on the 21st of June, in the year 1675, and the building completed in 1710. Sir Christopher Wren was the architect; and our young readers will perceive from the dates, that this building was begun in the reign of King Charles II. and was finished in the reign of Queen Anne; the former Church, in the same situation, had been destroyed by the great fire of London in the year 1666. The whispering gallery is considered a great curiosity. It goes round the bottom of the dome, in the inside of the Church; it is 140 yards round, and if a person whispers at the door on one side, any one who is on the opposite side of the gallery, though he is 140 feet from the speaker, taking the shortest road across, will hear the words loudly and distinctly sounded. The shutting of the door produces a sound like thunder. Those who like to go to the upper gallery at the foot of the lantern, may have a noble view of the city of London; but the buildings, and the people, and the carts and carriages below, have the appearance of a busy, bustling, crowded world, belonging to a diminutive little race of beings: the effect on a bright sunshiny day is extremely pleasing.

But large as St. Paul's Church is, it is small when compared with St. Peter's at Rome. We have given a drawing of both, that their different proportions may be

seen.

CHANGES OF A CATERPILLAR.

As we find it difficult to understand the resurrection of our bodies, let us learn a lesson in faith from the changes of a caterpillar. Look at that hairy grub creeping on

VOL. XVI.

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