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When the seed is committed to the ground, the process of vegetation begins. The external covering falls off, and the seed absorbs the surrounding moisture, till the enclosed plant gathers sufficient strength to burst asunder the lobes, and emerge into new being. The root penetrates into the earth, and the plume rises, under the protection of the lobes, above the surface. The latter do not, at this early stage of the plant's existence, merely serve to defend it from injury; the young vegetable is at present unable to provide itself with necessary nourishment, and is as much dependent on the seed-lobes as the newborn infant on the sheltering arms and nutritious breast of its mother. As a fond parent, therefore, protects and nourishes her helpless babe, so the seed-lobes ward off any rude assault from the tender plant, and prepare nutritive juices for its support, till its organs are sufficiently strong to perform their destined functions.

Every day gives new strength to the infant plant. The stem increases in thickness, and shoots up in height, and the first leaves begin to be fully developed; these are usually different in form from those which succeed them. The seed-lobes are now visibly decaying, and in a few days they perish altogether; the plant is then left dependent on itself.-It is impossible not to observe the analogies which run through the natural world. How strongly does the decay of the seed-lobes picture the dying parent, who, after exhausting all her energies for the present and future welfare of her child, sinks down, worn out with maternal solicitude, on the bed of death.

The first leaves of the plant do not continue for a great length of time; but shortly give place to what may be called the proper foliage. Branches, also, begin to shoot from the sides of the stem, each under the protection of a leafy prop; these gather strength, till in the end they are furnished with leaves similar to those on the main stem, and give birth to other shoots. The plant has now acquired that strength and vigour which promise to conduct it to maturity; let us then more particularly consider the mechanism of its several parts.

The root consists either of one tapering tube alone, or of this with subordinate branches proceeding from the sides. In the first case the root is a single capillary

How imperfect had been the mechanism of vegetation, if plants had not been furnished with leaves: at some periods the plentiful supply of gaseous fluid would have rendered them gross and unhealthy through repletion, whilst at others a scanty supply of nutriment would have induced their decay. The leaves may be viewed as excretory and secretory ducts, that serve either to carry off the unhealthy grossness of the plant, or to furnish it with the means of support in seasons of scarcity. By experiments with the air-pump, atmospheric air is found to be as necessary to vegetable as to animal existence, and the respiration of plants is performed by means of their leaves. These appendages are spongy, porous bodies, consisting of three distinct parts: the skeleton, or frame work, the external skin, full of minute pores, and the colouring matter of the leaf, which is adapted to absorb moisture. Either the superfluous nutriment of the plant is, therefore, brought through the capillary vessels into the absorbent of the leaf, and thrown off through the pores; or, if neces sary, the treasures of the night-dew are gathered into the absorbent, and transmitted into every part of the vegetable. Nor do the uses of the leaves end here: without their grateful shade, many of the more delicate plants could not sustain the heat of the sun, which would dry up their juices, and cause them quickly to wither.

When the plant has arrived at its full strength, a wonderful phenomenon takes place, to which its prior existence was only preparatory. It bursts forth into beautiful and delicate blossoms, which gradually expand into perfect flowers. The period is now drawing on, when the plant, having provided for the continuation of its species, begins to decay. The petals lose their brilliancy of colour, and fall from the stem, leaving the fruit or seed-vessel to ripen.

When the stamens and pistils are on the same plant, or included within the same flower, it is easy to conceive that the least motion of the plant, when the flower is ripe, will scatter a portion of the pollen on the stigma; and where the stamens and pistils are on different plants, situated at a distance from each other, the fertilizing

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dust is carried by the wind to the proper | organ. The economy of vegetable existence is completed when the plant has flowered, and produced seeds for the propagation of the species.

It is not necessary to occupy more space in this compendium, by enumerating the classes, orders, &c. of the Linnean system, which are distinguished by the number, situation, &c. of the fecundating organs, as these can easily be learned from any elementary work on botany. July 1st, 1829.

OBSERVATIONS ON LONDON BRIDGE.

THE Thames is a noble river; its situation in the south of England is well known; and in every sea-port in the known world its name is familiar with the merchants. The Thames is, indeed, a noble river, because all its parts sustain this exalted character. Its source is an ample spring, which flows so copiously, that its current, with the tributary rills around, form, during the first mile of its course, a river sufficient to work the machinery of a cornmill. Its course is long and interesting, and streams innumerable mingle with its flowing. It laves the most exalted seat of learning in the world; and the palaces of royalty crown its margin in its progress to

the ocean.

Stretching from west to east, across the island of Great Britain, amidst the southern provinces, after flowing through the metropolis, it disembogues itself into the North sea on the east, while on the west its current affords facilities to a junction with the Atlantic ocean and the Irish sea, as well as the principal sea-ports and manufacturing districts throughout the island.

These junctions are effected by means of canals, one of which connects the Thames with the Severn, and others with the Avon, the Mersey, and the Trent; which last affords a second outlet into the North sea. Thus does this noble river become navigable, taking in its artificial as well as natural ramifications, throughout the greatest portion of England. The important sea-ports of Bristol, Liverpool, and Hull, are thus opened to its commerce, as well as the lesser, viz. Chepstow, Gloucester, Runcorn, Chester, York, Selby, Goole, Thorne, Gainsborough, Grimsby, Louth, Boston, Spalding, and Lynn, without incurring the dangers of the seas; while the immense manufactories in the west of England and Wales, and in the counties of Worcester, Warwick, and Stafford, Salop, Chester, Lancaster, York, Nottingham, Derby, and

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Leicester, are intersected, and their products opened to regular and expeditious communications with London, the head of the British empire, and the first commer. cial city in the world.

If the source and course of the Thames are noble, its termination is noblissimus: presenting an ample front to the foaming brine, it rolls into the North sea, like an ocean into an ocean, fraught with the freight of every clime this capacious sphere affords: nor do the most stately barks disdain its channel. Ships of every grade, from the coaster to the tall East Indiaman, and from the bomb to the first-rate man of war, sail amidst its ample width, and anchor in its deeps with ease and safety: while vessels of the lesser class, innumerable, crowd its tide, and form "the floating millions of the Thames." "And last, not least," upon its banks are founded those great societies which forth to heathen darkness send the word of GOD; the prophets, also, send they, teaching words of truth, and, in His name who died for sinful men, proclaiming grace to all.

During a course of more than seventy miles, including the sinuosities of its channel, the tide flows up the Thames, rendering the navigation easy by its current upward, and commodious by the increased depth of water which the tide produces. A tide is the propagation of a wave, and pressing up a river, its impetus is continued to a given distance from the ocean, in accordance with certain circumstances which occur in the channel along which it flows. If the bed of a river is a plane which possesses considerable inclination towards the ocean, the tide is impeded by its ascent, gradually dies away, and at no great distance from the sea ceases entirely. If the channel of a river meanders considerably throughout its course, these sinuosities check the progress of the tide, by continually throwing its current into the bight, and thus at every turn lessening the original impetus of the wave, by causing it to set out anew. If the bed of a river contains abrupt ascents, they arrest the impetus of the wave at these points, and there the current becomes stationary; until the flowing tide surmounts the impediment, and, rippling over, sets out anew with enfeebled force. But if the bed of a river is an inclined plane, approaching the horizontal, and quite regular, the tide flows along its channel freely, ascends to a great distance from the ocean, and rises to a considerable height above its ebb.

There exist no natural impediments of

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these descriptions in the Thames, but athwart that noble river, at a most interesting point in its course, an artificial impediment of a formidable description has existed for ages, beneath that ancient structure called London Bridge, quite across, from the north to the south side. Whether we survey the segment of a cylinder when it forms an arch, resting upon its two extremities, or the segment of a sphere when it constitutes a dome, resting upon its base, we behold ponderous matter suspended in air by the juxtaposition of its parts. Adaptation of form, and nicety of fitting, must harmonize in these fabrics, when composed of such materials as bricks or stones, or the balance of weight in all their parts cannot be maintained; and the absence of this balance, either in the principle or in the execution, will expose the materials to the force of gravity individually, which will resolve the fabrics themselves into their component parts, and leave, instead of an arch or a dome, a heap of bricks or

stones.

It was the imperfect knowledge which the ancients had of these segments, that reared such difficulties in the way of the engineers of these times, whenever they attempted the construction of arches or domes in the large way; and I doubt not this very imperfection of knowledge in the engineers who erected that ancient fabric (called London-bridge, because it was the first bridge, and for ages the only bridge over the Thames in London) was the cause of that impediment in this noble river, now under consideration.

When a bridge is of considerable length, if the arches which compose it are small, they must be numerous; and as every arch must be supported by piers, of course these become numerous also; but a number of piers will necessarily take up a large proportion of the channel across which they are ranged, and obstruct the freedom of the current therein. Not only is London Bridge composed of a number of small arches supported by numerous piers, but these evils are awfully increased by a considerable, indeed a preposterous, increase of size in the bases of these piers. These, contracting the current of this ample river, and resolving it into so many rolling streamlets, pent up between potent barriers, obstruct, and raise the waters several feet on the upper side, and cause them to rush and roar through their narrow channels, threatening ruin to the smaller vessels that are precipitated down the steep; and, alas! they do not merely threaten, but often involve in ruin, not only

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the boats, but the watermen and passengers therein.

The improvements which the present age has made in the construction of bridges are no where evinced more clearly than in the striking contrast between the stately bridge, whose ample arches now bestride the Thames only a few yards above, and the miserable fabric under contemplation.

This new bridge, the arches of which are completed, will obstruct the current in such a trifling degree, that it does not deserve the name of an obstruction; and I do not know a finer study in architecture than the contrast which these two bridges, side by side, across the Thames, at this moment afford.

So soon as the New-bridge is completed, the Old-bridge, with all its obstructions, will be removed: it therefore now becomes us to inquire into the consequences of this removal. Two effects, the one diametrically opposite to the other, must result from the removal of this nuisance. First, the ebb will fall to a lower level above bridge, and secondly, the tide will rise to a higher level, and consequently flow further, up the river. These effects will naturally result from the freedom that will be given to the currents of ebb and flood tide, which, without obstruction, will roll forward, each in its several direction, and enjoy all the latitude of an open channel.

First, The ebb tide will fall to a lower level above bridge. Pent up, as it now is, the Thames above London-bridge partakes of the nature of a pond, the bases of the piers of the nature of a dam, and the spaces between these of the nature of wears. Thus is the water pent up above its natural level; and it can only run regularly off when it attains a height to force a current sufficiently impetuous, through these wears, to form an equilibrium between the outlet and the supply. This circumstance will somewhat impede the navigation of the river above bridge at half ebb and low water, because it will actually cause a decrease in the depth of water there and on the south side, especially, which is shallower in general up to Westminster-bridge than the north side, the difficulty of approaching the wharfs will be considerably increased at those seasons.

Secondly, the tide will rise to a higher level above bridge, and consequently flow farther up the river. The whole tide of flood, retaining its original impetus, will flow freely up the channel of the Thames from the ocean to the highest point possible; and therefore it may fairly be presumed that above bridge the line upon its banks, which is technically called high

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water-mark, will be somewhat higher than the present line. How much this height may exceed the present, must remain a subject of conjecture, seeing no certain data can be attained to on this head at this moment. In extraordinarily high tides, which flow at certain seasons of the year, or arise out of certain circumstances, such as storms at sea, when the gale sets the volume of water directly into the mouth of the river; or rains inland, which cause a heavy fall of water downward at the moment when a strong tide rushes upward, &c. &c. the freedom of action in the channel may, and we presume will, permit the water to rise up to a higher point than, under existing circumstances, it has attained. How much this point will exceed the present highwater-mark, whether six inches, nine, or twelve, or even more, where is the calculator who can favour us with an answer? Those whose premises immediately adjoin the Thames above bridge are, however, deeply interested in this event. If the tide should exceed its present extreme height twelve inches, or even six inches, considerable damages might ensue on premises, which, during ages past, have been secure; for ages have passed away since the nuisance beneath London-bridge was brought into existence. When we behold how closely the river is pent in with buildings, and how numerous these buildings are on both sides, taking in the range from London-bridge to Richmond, it cannot but excite some anxiety as to the consequences, when any portion of the property of such incalculable value as all these premises contain, is within the probability of individual injury or destruction. The histories of inundations along the banks of the Thames furnish us with calamitous instances of suffering, both as to property and persons, and such an alteration as the present, certainly will not decrease, while it may increase, the possibility of similar recurrences. If the tide should flow higher up the Thames than heretofore, it will of course raise the water in the river at those points higher than its ordinary level; and all the reasoning applicable to the distance between London-bridge and Richmond will apply to this extended line.

While we rejoice at the removal of a nuisance which has choked the course of one of the noblest rivers in the world for ages, and involved hundreds of mankind in destruction, a destruction which is extrajudicial, and out of the course of Divine providence; we rejoice, as we do in thousands of cases incident to mortality, with a

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SIR,-In the Staffordshire Advertiser of Saturday, May 2d, we are told of two explosions of hydrogen gas in coal mines, near to this place. This has reminded me of what I have for some time past intended, viz. to once more urge those, at all engaged in coal mines, to use the means of safety.

The scientific researches of your correspondent, who has so ably written on mephitic gases, merit, in my opinion, the highest commendations; but in a practical point of view, the subject requires line upon line, and precept upon precept, and that too in language so plain, that all who read may understand.

The means of safety being, in my opinion, obvious and certain, I cannot but consider the dreadful numbers of lives lost in coal mines, and of others maimed for life, as reflecting very much upon the proprietors of them. Were they as careful of the lives and limbs of their poor workpeople, as they are tenacious of their own pecuniary interests, we should hear less of these deplorable accidents.

Davy's lamps may have done good, and have been the means of safety to many; but there is no absolute safety, except in getting rid of the danger, and that is what I would wish to recommend.

There are three ways of preventing accumulations of hydrogen gas in mines: first, by having openings above every part in work, where danger is apprehended, so as to give free egress to the gas: secondly, to have flexible tubes, one end open at the place where it might accumulate, and the other end having an air-pump fixed thereto, the working of which, would draw out the gas: and thirdly, to have a perpetual lamp burning near to the roof of the parts infected, so as to consume the gas as it issued from the works.

Atmospheric air being twelve times heavier than hydrogen gas, and not spontaneously uniting with it, will, of course, force it upwards, and, where there is sufficient space, force it out of danger; for the danger arises from its compression at the roof of the chambers of the mine; and, therefore, if there is an opening upwards, it cannot explode. And if an open end

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of a flexible tube be fixed near to the roof, and the air be drawn through it, the gas will be drawn out first, and an air-pump of a very simple construction will answer the purpose. The discharging end of the tube should rise a little above the surface of the water in a vessel, with water, say about a foot or fifteen inches deep. The end of the tube should have a valve to work easy, opening outwards, so that air might come out of the tube, but not return. A cylinder of a foot or more deep, and say a foot wide, open at the lower end, and at the other closed, except a valve to open outwardly, will answer this purpose. Upon the cylinder being let down in the water, its top should be near to the top of the tube, and upon its being drawn up, there would be a vacuum, but for the air drawn from the tube, and this will be discharged by the valve, upon its being let down again, and by this means gas or common air may be drawn from the interior of the mine, and, if discharged at the bottom of the shaft of the mine, it will find its way upwards.

The combustible quality of hydrogen gas is well known, and is highly valuable, as may be seen in many of our large towns, factories, and shops. It is quite innocent if brought into contact with a blaze, and the oxygen of atmospheric air in small quantities, and under proper management, and the gas emitted from coal works may, no doubt, be brought to give light to those dreary regions: at any rate, it might all be consumed with safety, and, indeed, I am told that it is consumed in some mines.-Yours, &c.

THOS. BAKEWELL. Spring Vale, near Stone, May 7th, 1829.

RAPACITY AND ITS EFFECTS.-. - Badajos, January, 1828.

A LADY of great respectability, of the name of Donna Elvira Mendinuetta, aged 77, the widow of one of our generals, had the reputation in this town of possessing a great deal of money. Only her niece, Donna Maria de los Dolores Santander, lived with her. It was said she would inherit all that Donna possessed; who, being very old, it was momentarily expected that Maria de los Dolores would become mistress of her aunt's fortune.

Exclusive of these pecuniary expectations, Maria de los Dolores was very handsome in her person; she, therefore, did not want admirers; but this virtuous young lady would not give ear to them, and concentrated all her cares upon attending her aged aunt.

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During the late political events, Don Jose Ribero had forfeited all his fortune for having bought several ecclesiastical estates, the sale of which had been authorized by his majesty. These were taken from him again, on the monarch's return from Cadiz, in 1823; and, like all purchasers of national property, he lost both his money and his estates. Thus circumstanced, Don Jose Ribero turned broker; but being neither licensed nor sworn in, he acted only as a sort of poaching broker-namely, irregularly and by stealth.

Donna Elvira Mendinuetto had divers little matters of business to settle; and, as she had been for some time acquainted with Ribero, she commissioned him with the same. Maria de los Dolores took an interest in the unhappy fate of Ribero, and this sentiment was presently succeeded by another. Ribero was an honest man, and perfectly disinterested, but by no means insensible to the charms of the young lady. They came presently to a mutual understanding. This was mentioned to the aunt, who not only approved of their reciprocal affection, but calling them one day to her, she said to them-"I am very glad of your mutual passion, and wish to see you united; but, as I have much experience, I should wish a year to elapse before this takes place. Perhaps I shall not live to see that period, advanced as I am in years; but even should I close my eyes, my niece would surely go into mourning for me for about six months, and not marry during that time, by which means I should succeed, although dead, of partly during my own life and partly afterwards, subjecting you to this trial; however, as God may, at any moment, call me into his divine presence, I wish you would send for a notary to draw up my will."

In this will she appointed her niece uni. versal legatee.

Some time afterwards she fell ill; her confessor, who was a Franciscan friar, advised her to forbid her niece having any connexion with Ribero, because he was a freemason-which is equivalent to a Jew and heretic-and assured her it would prove d- -n, not only to herself, but likewise to her niece, to listen to the conversation of such an impious wretch. The friar availed himself of the advanced age of Donna Elvira, and of all the arts which Monks know how to display on such occasions, to persuade her to make a fresh will, to annul part of her former one; which he brought about, by her adding the condition-"That she insisted upon her universal legatee and executrix, Donna Maria de los Dolores San