miner of his danger from foul air, as on coming in contact with it, the flame dilates and changes colour. In places where the air is not so foul, the mine is frequently lighted up with common lamps, and by the men carrying candles. The different shafts of a mine are likewise used for the important purpose of ventilating it. By lighting a large fire at the bottom of one shaft, a quick and powerful upward draft is produced; to supply the vacuum thus created in the mine, a current of fresh and cold air rushes down the other shaft. A circulation of air being thus secured, the fresh air is, by means of trap-doors and other contrivances, conducted into every part of the mine where the men are working, before it is permitted to escape at the "upcast" shaft, or that where the fire is; the other is called a "downcast" shaft.

In digging, the miners meet with many springs, some of which are possessed of strong saline properties. Sometimes the miners pierce strong springs, or old workings, which during many years have been reservoirs for water, when the water rushes into the mine with great force, and drowns the men. The water must then be got out of the mine before the working can proceed. This is done by vast pumps, worked by steam-engines; one stroke of which will raise as much water as five hundred men could pump out. Whilst sinking a pit recently, in the county of Durham, a feeder of water was encountered which required the engines to pump upwards of four thousand gallons in a minute.

Where the roof of the mine is bad, it is supported with timber. Portions, however, sometimes fall before their weakness is discovered by the miners, not unfrequently causing death. Accidents of this kind are, however, from their nature, limited in their fatal consequences; and they sometimes are the occasion of most singular hair-breadth escapes. If the roof fall when the mine is foul, and damage any of the lamps, then there is great risk of an explosion. Some explosions are accounted for in this way.

The depth of "some" of the mines should be stated at "upwards of fifteen hundred feet." One is 1700: 1000 and 1200 feet are now frequent.-Say 170 to 200 fathoms,

THE METEOR.

A SHEPHERD on the silent moor
Pursued his lone employ,

And by him watched, at midnight hour,
His loved and gentle boy.

The night was still, the sky was clear,
The moon and stars were bright;
And well the youngster loved to hear
Of those fair orbs of light.

When lo! an earth-born meteor's glare
Made stars and planets dim;

In transient splendour through the air
Its glory seemed to swim.

No more could star's or planet's spell
The stripling's eye enchant:
He only urged his sire to tell

Of this new visitant.

But ere the shepherd found a tongue,
The meteor's gleam was gone;
And in their glory o'er them hung
The orbs of night alone.
Canst thou the simple lesson read
My artless muse hath given?
The only lights that safely lead

Are those that shine from heaven.
One far more bright than sun or star
Is lit in every soul;

To guide, if nothing earthly mar,
To heaven's eternal goal!-BARTON.

RESISTANCE OF PLANTS TO THE
WINDS.

THOUGH the uses of the winds have often been
pointed out, I know not who has remarked on that
beautiful balance of force and resistance by which
the velocity of the atmosphere, or uniting to this the
appointed gravity of that body, its momentum, is
kept within the bounds necessary to the safe existence
of the vegetable world. It must not be said, as it has
often been asserted of creation, that this limit of force
was contingent on the constitution of the atmosphere
and the moving powers; and is therefore a necessity,
not the result of design. There are hurricanes,
as permitted evils, or appointed variations for special
ends; and if they are among the usual exceptions to
what we deem a perfect order of things, so do they
prove that such forces might occur more frequently,
or act perpetually, had it been ordained or permitted.
But to have done this would have been to destroy the
vegetable races, or else to demand the construction of
stronger ones, endued with the necessary resisting
power.
And in this is seen the balance in question :
it is an adaptation made in wisdom, not a chance ;
while if we compare the apparent feebleness of struc-
ture so frequent in plants, with the extent of exposure
and the enormous forces to which they are so often
subjected without injury, we cannot fail to be inter-
ested in the facts, and in the means by which these
compensations are effected.

Those facts are open to every one. There is no tree so large, no plant so humble and tender, as not to resist the strongest gales; with exception of those rare excesses which form parts of the appointed destructive powers of creation. The tree is rarely broken, more rarely uprooted; scarcely does it lose the tenderest branch, when bending for days to the blast : and even the leaf, attached by a slender stem, and destined to fall at no distant day, defies the storm while its appointed office is required. The flexible and feeble rose-bush is tormented by the winds as if it would be dispersed in fragments, yet scarcely a petal is displaced till the time approaches when it would have fallen without a touch. It is intended that they should aid in scattering the seeds of plants: yet never perhaps was an unripe one detached by the utmost severity of the gale, tender as its attachment may be, tender as we know it to be in the case of the dandelion. No one, knowing the nature of these parts in plants, and not knowing these facts, could have expected such resistance: it is only the experience of the cultivator which tells him, that neither will his corn-stalk be broken nor its seed dislodged, by aught less than the hurricane or the whirlwind.

All this is effected with the utmost facility, not through strength but through weakness; by yielding, not by resistance. In lieu of that which could not be granted, the parts of plants have been endowed with flexibility and elasticity, in addition to such tenacity as was admissible: they are the corrective and compensating power, and the result shows that the adaptation is perfect; while we cannot doubt the design, when we find that elasticity, one of the most" beautiful and mysterious of the laws of matter, intended not only for evading force, but for equalizing and continuing motion, is diffused through the vegetable world, wherever it can serve this purpose, and no where else; effecting the ends in view, here as elsewhere, through the gradual instead of the sudden retardation of communicated motion.

Should a vane be fixed, it would be broken or bent by the storm it is free to move, and in this motion it finds a shelter from violence. Thus also is a leaf empowered to place itself in a parallel to the stream

of wind, and thence to defeat or elude its force; while the flexibility and elasticity of the foot-stalk enable it to conform to the most capricious and sudden changes; insomuch that there is scarcely an attachment so feeble as to be insufficient for security. To go through even a small part of the variations which occur in different plants under this principle, to show how, under different degrees of strength and of flexibility, and under differences in form and in the modes of resistance and escape, the desired end is always attained, would far exceed these limits: the student of nature may pursue this investigation through the whole range, down to Nasturtium, (Tropæolum,) where the length and flexibility of the foot-stalk still form an effectual remedy, though the principle for the construction of a leaf and its stem is reversed.

If the herbaceous plant is low that it may find shelter, or otherwise evade the winds, the tall tree is protected by some peculiar construction or qualities. The fir tribe is little flexible or elastic, because this would have interfered with the destined purposes of its wood for the uses of man; but, in compensation, its foliage is such that the winds can pervade it more easily than that of any other trees. Under that of the oak it would have been destroyed: while this tree, reversely, opposing to the winds a solid mass of leaves, is strong both in material and form, although little yielding, The no less full ash bends to the blast, through its flexibility, recovering by its elasticity, while its high tenacity constitutes the remainder of its protection. If the Cactus, Agave, and many similar plants, are neither tenacious, nor flexible, nor elastic, they are strong in form and in structure; the latter resembling that contrivance in bones, by which bulk is produced without weight, and strength without mass of materials. In the vine, and in many more plants; in bryony very remarkably, the tendril does not serve merely as a support; since in curling itself far more than is necessary for that purpose, it becomes a spiral spring, allowing the plant to yield to the winds, and restoring it to its place as their force passes away. It is almost superfluous to point out how the delicacy of the foot-stalks in the panicled grasses, added to the elastic flexibility of the whole stem, defends the flowers from any torments the storm can inflict while interesting variations will be found in Aira, Agrostis, Briza, and many others, with examples of elasticity in many more, not always exceeded by that of our metal springs. And if, in this tribe, the length and flexibility of the filaments afford singular protection to the anthers, independently of the more direct purpose which they serve, in permitting their contact with the surrounding stigmas, so does the anther, almost every where, afford another example of contrivance subservient to this purpose, if to move, in that articulation which so far exceeds the ball-andsocket joint in freedom, that it almost seems as if no attachment existed. One other circumstance may be mentioned; that which, depending on the sensibility of the vegetable organization, is only called into action when it is wanted; being displayed in the increased action of the tendrils, in the further spreading or growth of the roots, and in that general increase of strength which follows from exposure, very remarkably in the outer trees of a forest.

It must suffice to have thus shown, that in this department of life the Divine wisdom has adapted the resisting powers to the injurious forces, through a great diversity of contrivances, and with a success as perfect as the general intention is unquestionable.

[MACCULLOCH's Proofs and Illustrations of the Attributes

of God.]

ELECTRICITY.

No. VI.

ELECTRICAL EXPERIMENTS.

THE electric spark is an object of peculiar interest to all classes of observers, especially to philosophers. When an electrical machine is in good action, if we bring the knuckle, or a brass ball, near the positive conductor, brilliant sparks, or rather streaks of light, will dart from it; following each other in quick succession, but varying in their colour and form, according to the distance to which they are transmitted. When the spark is received by the knuckle, it is necessary to turn back the cuff of the coat, to prevent the electricity from being conveyed by it from the machine. This precaution is also applicable to other parts of the dress, which should be properly secured whilst conducting all kinds of electrical experiments; for if permitted to get near the apparatus, they will materially interfere with the results.

The best method of investigating electrical light, as it is exhibited when passing through air, is by means of two brass balls, each about two inches in diameter. One of these balls must be fixed to the conductor, at that part farthest from the machine, and the other held in the hand of the operator. The latter ball being placed at what is termed the striking distance from the other, and which depends on the size and power of the machine, a spark or flash of white light, tinged at one of its extremities with violet, will pass between them. On gradually separating the balls, the sparks will pass less frequently, and as the distance increases, the violet colour will prevail. If a ball one inch in diameter be substituted for that attached to the conductor, electricity of higher intensity will be obtained, and it will consequently pass through a greater space.

Under these circumstances, and with a twenty-four inch plate machine now before us, the sparks can be made to vary from four to ten inches in length. As their length is increased, they assume a zigzag, and ultimately a forked appearance, exactly resembling lightning; and instead of proceeding direct towards the centre of the large ball (which is held in the hand), they seem attracted by irregularities at various parts of its surface, or probably by particles floating in the atmosphere, but which are too minute to be detected. The colour of these sparks or flashes is fainter in proportion as they are more diffused, changing from violet to deep red.

We have always found the part of the conductor of a plate machine at which the longest sparks can be taken, is at the angle where the piece is returned which carries the steel points. When the machine, to which we just now referred, is in good condition, and the atmosphere favourable, we have no difficulty in obtaining from it, at the part we have mentioned, a rapid succession of sparks, from nine to twelve inches in length. It is also deserving of notice, that the time most favourable for the developement of these sparks or flashes is during the first three or four turns of the machine, immediately after its action has been for a few minutes suspended.

With a cylinder machine the phenomena attending electrical light can be illustrated somewhat differently from the manner we have described; by which we learn that the forms as well as colours of the sparks are determined (other conditions being the same) by the nature of the electricity; whilst they partake of a mixed character when one substance is positively, and the other negatively, electrified.

Nor must we omit to mention that the size, form, colour, and other attributes of the electric spark,

depend on the nature of the substances through which it is transmitted, or upon which it is received; as also on the forms of those substances, and the direction in which the spark enters or leaves them; and whether it merely passes over, or penetrates beneath, their surfaces. Thus, the sparks which pass between the polished surfaces of most of the metals are intensely white; but when communicated by a metal to any part of the human body, their colour inclines to violet. The sparks taken from ivory, box, and some.other kinds of wood are red, as they are also from green vegetable substances, from ice, or water, and in some cases from iron. From chalk, and many other minerals, their colour is white, occasionally tinged with yellow; whilst those from loaf-sugar, and gilt or silvered leather, are a beautiful green.

But in many instances these colours are modified by particular circumstances, and by imperceptible gradations become so nicely blended, as to lose all traces of their several peculiarities. This is effected by merely altering the forms, or changing the relative positions, of the substances above enumerated. For instance: if we fix a piece of stout wire (about six inches long, and having a sharp point at one end), upon the conductor, and bring near to it a brass ball, at a certain distance from its point, a rapid discharge of brilliant sparks will ensue; but on slowly withdrawing the ball to a greater distance from the point, the sparks, gradually changing from white to violet, will at length disappear; their place being occupied by detached rays of violet-coloured light. If we now reverse this experiment, fixing the ball on the conductor, and approaching it, at the same distance as before, with the point, there will be only a bright speck or star on the latter; the whole of the electricity excited by the machine being in this case silently and almost imperceptibly withdrawn.

This experiment can be varied in the following manner :-Insert the pointed wire into a piece of glass tube about its own length, and quite smooth at the ends. On presenting one end of the tube, with the point just protruding, to the conductor, and then slowly withdrawing the point, sparks will pass between it and the conductor, within the tube, in the same manner as if a ball were used.

As the influence of points upon bodies charged with electricity will occupy our attention more fully by and by, we shall only remark here, by way of caution, the necessity of avoiding angular and sharppointed projections in the preparation of electrical apparatus, the various parts of which, whether of wood, glass, or metal, require to be finished with their surfaces and edges as smooth as possible.

Now let us describe a few, among the many, ingenious contrivances, for exhibiting the electric spark when passing through air, and its effects on various substances which may be placed within its influence.

We begin with the spiral-tube, which is sometimes fitted with a spherical brass cap at each end, and is then intended to be held in the hand, or it can be fixed to a stand, as in the accompanying figure. It is constructed in the following manner :-two glass tubes, one to go within the other, are provided; the smallest being about three-fourths of an inch in diameter, and eighteen inches long, and the other an inch shorter. On the outside of the small tube discs of tinfoil are pasted in a spiral form, a

than the other, that it may enter the brass cap ▲, and by means of a piece of tin-foil, be brought into metallic contact with it. The end A being placed at the distance of about an inch from the conductor, on turning the machine a series of beautiful sparks, following each other very rapidly, will pass along the tube, and when the room is darkened will resemble a continuous stream, rather than intermitting coruscations of light.

h

It will of course be understood, that if the discs were in contact, the effect, as described, would not be produced; for electricity is not visible when passing through good conductors; the light, therefore, is occasioned by its forcing a passage across the thin column of air interposed between the edges of the discs. Here is another piece of apparatus, consisting of five spiral tubes, abc (not seen in the fig.) d and e, which are arranged around a stand K, on the centre of which is fixed an insulated glass pillar г. At the top of this pillar is a small brass rod, l, a placed horizontally, to which are attached three brass balls, ghi, and underneath the latter ball is a small pivot, on which the rod revolves. The lower extremities of the tubes are in metallic contact, a thin brass ring being let into the stand for that purpose.

con

The conductor, or, what is more convenient, a jointed arm nected with it, being brought immediately over the ball i and the rod

set in motion, on working the machine, the rod will revolve with considerable velocity, communicating electricity to each of the tubes in succession, which will exhibit streams of light in a spiral form, and in the dark it will appear as if the tubes themselves were in motion, the illusion being assisted by reflection from the glass pillar in the centre.

Luminous words and figures are also successfully employed in illustrating the properties of electricity. Let abcd be a neat frame of well-seasoned mahogany, containing two plates of glass, of equal size and perfectly flat; on one of the plates narrow strips of tin-foil are pasted, forming an unbroken connexion throughout the seven parallel lines, which extend nearly from end to end of the glass, communicating at one extremity with the brass ball E, and at the other with F. When the paste is dry, the foil is divided by a sharp knife, the separations being so arranged that they may form the word LIGHT, or any other word or device that may be required. The other plate of glass is intended only to protect the tin-foil from dust or accidental disarrangement. The ball E being placed near the conductor, whilst F communicates by a chain with the floor, on passing a succession of sparks through the foil, the word or device delineated on it will appear in luminous characters on the surface of the glass.

JOHN WILLIAM PARKER, WEST STRAND.

PRICE SIXPENCE. Sold by all Booksellers and Newsvenders in the Kingdom.

WANDERINGS IN THE DESERT-DEATH OF AARON AND MOSES.

THE ceremonial law of the Jews was directly designed to preserve them as a peculiar people, dedicated to Jehovah their God and King. Their form of government was a Theocracy; the Almighty himself was their sovereign, and He made known his edicts by the authorized interpreters of his will. But it was necessary under such a constitution to take especial care that no pretender should mislead the multitude, as the High Priest delivered the responses from the oracular Urím and Thummím, by which all affairs, religious, civil, political, and military, were regulated; grave evils were likely to occur if there had been any room for doubt as to the person who should have the exclusive right to discharge such important functions. The priesthood was therefore rendered hereditary in the family of Aaron, and the performance of minor sacerdotal duties was restricted to the tribe of Levi. It is sufficiently obvious that the hereditary priesthood was not only an essential element of the Theocracy, but the very bond of union by which all the parts of that constitution were held together. Hence, as we have seen in the preceding article of this series, the revolt of Korah was severely punished, and the sacerdotal privilege of offering incense invested with singular importance. But another miracle was wrought to confirm the priesthood of Aaron, to which it is necessary to direct attention.

The Lord spake unto Moses, saying, Speak unto the children of Israel, and take of every one of them a rod according to the house of their fathers, of all their princes according to the house of their fathers twelve rods: write thou every man's name upon his rod. And thou shalt write Aaron's name upon the rod of Levi: for one rod shall be for the head of the house of their fathers. And thou shalt lay them up in the tabernacle of the congregation before the testimony, where I will meet with you. And it shall come to pass, that the man's rod, whom I shall choose, shall blossom and I will make to cease from me the mur

:

murings of the children of Israel, whereby they murmur against you. And Moses spake unto the children of Israel, and every one of their princes gave him a rod apiece, for each prince one, according to their fathers' houses, even twelve rods and the rod of Aaron was among their rods. And Moses laid up the rods before the Lord in the tabernacle of witness. And it came to pass, that on the morrow Moses went into the tabernacle of witness; and, behold, the rod of Aaron for the house of Levi was budded, and brought forth buds, and bloomed blossoms, and yielded almonds. And Moses brought out all the rods from before the Lord unto all the children of Israel: and they looked, and took every man his rod.

And the Lord said unto Moses, Bring Aaron's rod again before the testimony, to be kept for a token against the rebels; and thou shalt quite take away their murmurings from me, that they die not. And Moses did so: as the Lord commanded him, so did he. (Numbers xvii. 1—11.)

The memory of this signal miracle was perpetuated among the Jews not only by the preservation of the rod, but by their coins, for the most common impression on the shekels of Jerusalem was the almondflowers that budded on the rod of Aaron. From the monuments we see why this peculiar test was chosen; the wand or rod was the official ensign of dignity among the Egyptians like the sceptres of the Greeks, or the white staves used in most modern nations; the heads of the tribes therefore presented to the Lord the emblems of their station, and the singular miracle wrought in Aaron's favour was the strongest reproof of their rebellion and unbelief, and the most signal confirmation of Aaron and his family having been chosen to fill the place of God's ambassadors, and to

THE ROD USED AS AN ENSIGN OF OFFICE.

So familiar were the Israelites, during their resi dence in Egypt, with the notion that the rod was the emblem and cognizance of dignity, that they never afterwards disputed the title of Aaron to the High Priesthood. Soon afterwards they had another opportunity of seeing the efficacy which God had given to this ensign of dignity, when Moses, by striking the rock, produced springs of water at Meribah. But on this occasion Moses and Aaron showed a want of confidence in the power and promises of the Almighty, which was the more criminal on account of the mighty miracles that had been so recently wrought in their favour. They were punished by being excluded from the Promised Land, and condemned to die in the wilderness. As the congregation journeyed from Meribah, an unexpected obstacle was offered to their progress: the king of Edom refused to allow the Israelites a passage through his territories, and they were commanded by God not to force their way, but to take a circuitous route by the mountains on the frontiers. The country which they traversed has only been recently explored by the enterprise of European travellers, and though more than three thousand years have elapsed since the Exodus, the country through which they travelled bears many decisive proofs of the truth of the Scriptural narrative. The name of the desert, El Zih, or the wandering, is a testimony to the wanderings of the Israelites. Laborde, whose travels through that country abound in the strongest confirmations of the veracity of the Pentateuch, says, "The Bible is so concise, but at the same time marked by so much precision and truth, that it is only by close and fixed attention to every word of its statements, that its entire merits can be discovered." This is singularly verified by the existing monument confirmatory of the events recorded to have occurred at Mount Hor.

The Lord spake unto Moses and Aaron in Mount Hor, by the coast of the land of Edom, saying, Aaron shall be gathered unto his people: for he shall not enter into the land which I have given unto the children of Israel,