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current of air established and preserved by a furnace under ground, which causes the rarefied air to ascend by what is termed the up-cast pit, while the denser atmospheric air descends by the down-cast pit;-ventilation by steam, in which the air in the up-cast pit is heated, and thus caused to ascend by means of an iron cylinder, discharging the steam of a boiler at the surface into it ;-ventilation by means of a hot cylinder, the up-cast pit terminating in an iron cylinder which is enveloped in the flame of a furnace;-and ventilation by means of an air pump, in which a wooden exhausting pump draws the air from the up-cast pit. One of the greatest impediments to the success of ventilation, by means of a furnace, is, the danger that the air may be so contaminated with inflammable gas, when it arrives at the furnace, as to take fire and explode. This difficulty Mr. Buddle obviates, by making use of two downcast pits, and one upcast pit, with furnaces between each of the former, and the latter; one of these furnaces is sufficient to keep up the current of air, and consequently that may be used, which is out of the reach of any discharge of gas which may casually occur.— The possibility of discharges of gas or blowers on both sides of the upcast pit, is practically so slight, as not to require any further provision.

As, however, the fatal effects of explosions are not confined to those who are destroyed by their immediate effect, precautions are requisite to avoid their remoter consequences.

In the many fatal accidents which have occurred within my knowledge, from explosions of inflammable gas, I think I may venture to assert, that not more than one-fourth of the persons they have ultimately killed, have been the victims of their immediate effects. Three-fourths of them almost invariably perish by suffocation; for, after the stoppings. trap doors, &c. are swept away by the destructive ravages of an explosion, it is, in general, quite impossi ble to restore the main channels of ventilation in time to relieve those whom the blast has left uninjured, who have missed their way, or are too weak or maimed to reach the adit of the mine. The difficulty of relieving the sufferers, in cases of this nature, arises from the mais bearing stoppings, or main doors being blown out, or broken down by the shock of the explosion.

Stoppings and doors are generally replaced immediately after an explosion, by half-inch deal; and though the overmen, &c. have acquired the greatest dexterity in this sort of operation, yet because they have often to scramble over heaps of ruins shaken from the roof, or blown out of different parts of the mine, and always in a great measure, to work in the dark (on account of the steel mills eliciting a very feeble light in the thick smoke and dust raised by the explosion) their proceedings are necessarily slow, and the persons they are hastening to save are often suffocated before they can possibly ach them.

'But a Viewer, who has accurately treasured up in his mind the various circumstances of his collieries, and reflected upon the probable causes and effects of explosions, which, as in the four cases hereafter to be enumerated, in spite of his skill and industry may occur, not only in a measure foresees the extent of the injury they may occasion, but guards against their effects, by supporting the bearing stoppings with pillaring of rough walling.

But though the bearing stoppings can be fortified in such a manner as to resist the shock of all ordinary explosions, yet because great strength cannot be given to the main doors of the avenues leading to the working boards, a degree of security to them is still a desideratum. The consideration, however, that art might accomplish an object to which mere strength is inapplicable, has lately led me to the invention of the swing door.

"The fittest materials for its construction, are deals one inch, or one and a half inch thick, and moderately loaden with a weight at its bottom h, so that if the prop g be struck out, the door, after ceasing to vibrate, will hang vertically over its threshold c. Its bottom and sides may be lined with soft leather, to make it fit closer to its cheeks and threshold; and the cheeks should be fixed in recesses, hewn out of the sides of the drift or passage in which it is to be hung.' pp. 12-15.

It is proved, by experience, that animal life may be supported in air contaminated to a degree beyond the point at which it would fire on contact with the flame of a candle, and colliers are often willing, and sometimes necessitated, to work in an atmosphere of this description. The steel-mill is then employed to obtain light, which is elicited by the action of a thin plate of steel rapidly turned against the edge of a flint. Mr. B. bas never witnessed an explosion of the gas from this kind of fire, but he accurately describes the change of appearance in the sparks, in different degrees of impurity, so that the approaching danger may be perceived.

When elicited in atmospheric air, they are of a bright appearance, rather inclining to a reddish hue, and as they fly from the wheel, seem sharp and pointed. In a current of air, mixed with inflammable gas above the firing point with candles, they increase considerably in size, and become more luminous.

On approaching the firing point with steel mills, they grow still more luminous, and assume a kind of liquid appearance, nearly resembling the sparks arising under the hammer from iron at the welding heat. They also adhere, more than usual, to the periphery of the wheel, encompassing it, as it were, with a stream of fire: and the light emanating from them is of a blueish tint.

When the inflammable gas predominates in the circulating current, the sparks from the steel mill are of a blood red colour; and as the mixture increases, the mill totally ceases to elicit sparks. They have the same bloody colour in carbonic acid.' p. 21.

The means employed by Mr. B. to ventilate pits, produce what he terms a standard air course, in which the air moves through an aperture of thirty or forty square feet, at the rate of three feet per second, discharging about 700 cubic feet per minute. This is sufficient to render harmless a discharge of 170-230 hogsheads of gas per minute; but where the discharge is greater, it proves inadequate.

In this case, recourse must be had to other means, and every friend to humanity must wish that they may soon be afforded by the improved mechanical or chemical resources of our age.*

Art. VI. Memoirs of Mrs. Harriet Newell, Wife of the Rev. Samuel Newell, American Missionary to India; who died at the Isle of France, Nov. 30, 1812, aged Nineteen Years. To which is added, a Sermon, on Occasion of her Death, preached at Haverhill, Massachusetts. By Leonard Woods, D.D. Abbot Professor of Christian Theology in the Theol. Sem. Andover. London: Booth and Co. 1815. sm. 8vo. pp. 197.

THE name of a

name of a Missionary can seldom fail to excite some peculiar kind of emotions, but emotions that differ widely. in different persons. In many, the only feeling produced, is that of ridicule. Enthusiasm and delusion,-the extravagance of a maniac united with the superstition of a fakir,-are ideas which it naturally suggests to them; and the sneer of superior rationality is played off as a thing of course; as necessary to support the reputation of worldly wisdom and unfanatical views. By this class of persons, the subject has never for one moment been submitted to sober inquiry, but flippantly adjudged to be undeniably absurd.

There is another description of persons, by whom it has been thought of occasionally, for a few moments at a time, when it has fallen in their way; but the images-the lively, forcible images, of a comfortable fireside, of a rich and plentiful

* Since the above Article was written, we learn that Sir Humphrey Davy has, within the past month, submitted to the Royal Society, a lamp, or rather a lanthorn, which promises to be one of the most important inventions of modern science.

The action of the lanthorn depends upon the following principles. The combustion of the oil, furnishes a portion of carbonic acid, while the air which maintains the combustion, affords a portion of azote or nitrogen. These gaseous fluids are produced, in the lanthorn, in such a quantity as is just sufficient to maintain a feeble flame :-and this flame becomes extinguished by the admixture of inflammable gas, or carburetted hydrogen, if any present itself.

Should this discovery prove effectual, the Professor will have deserved some tribute of national gratitude.

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table, of good wines and good beds, good houses and good servants, and of good old England, present themselves with so great a degree of vivacity to their minds-perhaps, in regard to this class, it might be nearly as correct to say, to their bodies,-that though it must, upon the whole, be admitted as a proper sort of thing to convert heathens into Christians, and though, if any can be found to undertake such a business, it is all very 'well; yet, the Missionary is regarded as an adventurer destitute of almost every feeling common to human nature; a creature of quite another kind; fated, by his own strange taste, to forego all the pleasures of life and society, and set apart, therefore, from any claim on general sympathy. He was born for one sort of life, they for another; and if he does not object to his own, it is all very well.'

We do not often meet with a person whose character is much lower than this, and yet a much lower may be found;-not indeed more" earthly or sensual," but more "devilish." It is that of the cool thinker who examines the subject well, calculates all its bearings, and at length determines, without one pang of remorse, one chill of horror, one throb of pity, one blush of shame, that the Missionary, by releasing the minds of men from a slavery fatal both to their present and their future happiness,-by exalting them from the state of mere human machines, to that of intelligent agents,-is opposed to certain political interests, and is therefore to be proscribed, driven by the arm of law from every spot of earth from which a grain of gold, or a skein of cotton, can be procured. There is a baseness-a malignity in this, beyond which imagination cannot proceed without approaching the confines of hell.

But it might have been expected, that among Christians, those who not only bear the name, but appear to sustain the character, no diversity of feeling on such a subject could exist. -That having been taught the value of one soul, they could not form a low estimate of the worth of thousands of hundreds of thousands, partaking of the same nature with themselves, who, if denied missionary aid, must sink, through the grossest vices, into perdition. It might be supposed, that the command of their Saviour, lying unrepealed upon his disciples to the end of time, to "go into all the world, and preach the Gospel to every creature," would prove a warrant to missionary exertions, which no Christian voice could dispute, no Christian heart could withst ind. And yet, with what uneasy suspicion has the subject of missions been regarded, even by some Christians!It is a business to which they have not been accustomed. Their pious forefathers went to heaven without thinking of it. It is novel, irregular, and a little fanatical. It overlooks objects of equal commiseration at home; is beginning to civi.

lize at the wrong end; and aims at good which human efforts can never accomplish. It is, therefore, presuming;-Providence, without such assistance, would fulfil all his intended purposes in their appointed time. In our hands it is exposed to disappointment and failure, and we to disgrace as unsuccessful schemers. Perhaps it sprung up in a wrong quarter,—not exactly among our own friends; it was not therefore cordially embraced by us at the commencement of its exertions, and it is unpleasant to yield a late consent, a consent which tends virtually to the acknowledgement, that we have hitherto been wrong, and you have the glory of forming and carrying on a great design without our co-operation; henceforth, we could be but converts-and, after all, it is difficult and fatiguing to acquire a just opinion upon such a controverted point.

By feelings such as these, more or less defined, there is reason to fear that some have been influenced, who were not insensible to the value of their own souls, nor altogether indifferent to the salvation of the heathen; some who have been unable to refuse a shew of concurrence in missionary exertions, and a little pecuniary support to the cause. But is this chastised approbation a temper of mind suited to the contemplation of a work, the greatest in which human agency can be employed?— the most benevolent in which Christian feelings can indulge?— a work enjoined by the will, and encouraged by the promises of God? It is not to the head so much as to the heart of such objectors, that appeal should be made; and we know of nothing more likely to subdue latent opposition, and elicit the feelings of Christianity, wherever they really exist, than the interesting Memoir which we have just perused. It is a living argument, well calculated to make its way to the living principle of piety, however feeble or encumbered, and to eradicate every prejudice but those which arise from sordid selfishness, or from enmity of heart to God.

A considerable part of the Memoir of a life so short as was that of Mrs. Newell, must necessarily refer to very early youth, and the extracts given from her letters and diary, written before her mind had received that particular bias which will endear her name to the Christian public, differ but little from what might be selected from the experience of many, who have continued to move in a private sphere. For this reason, these papers may be thought to occupy too large a proportion of the volume, as some, who may open it in expectation of feeling a peculiar and high interest in every page, will probably be disappointed at finding nearly one third of it thus occupied. But even here are exhibited two features worthy of attention, as distinguish ing Mrs. Newell's character; the one, a deep impression of the relative worth of time and of eternity; the other, arising from this,

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