ACCIDENTS IN MINES.

The chief causes of accidents in mines are explosions of firedamp, inundations, and falls of stone. There are also accidents arising from the breakage of ropes and chains, and the derangement of machinery.

Explosions may also arise from any of the following causes : In working in the whole mine, candles being commonly in use, the air, in consequence of bad ventilation, may be gradually loaded with fire-damp to the firing point, in which case we will have a thorough blast, but this is a rare occurrence.

We may have a good ventilation, but a sudden outburst of gas from a blower may rapidly raise it to the firing point. This I believe to have been the cause of many explosions.

The ventilation may wholly cease, from the neglect of doors or injury of stoppings. In this case a district may soon be filled with inflammable air, which would probably result in explosion. An accident happening to a safety lamp where gas is present may also cause an explosion.

And, as before stated, a good ventilation, mismanaged so as to cause the pressure of the air currents to be from the pillar or lamp districts into those worked with candles, may also be attended with fatal results.

The question is-Are any or all of these causes of accident controllable, and to what extent?

There is no excuse for any deficiency arising from a want of air; because it is quite sufficiently established that a quantity sufficient to meet all ordinary cases may be easily caused to circulate through the workings of a mine, the only requisites being a powerful furnace or the application of some other artificial means of producing ventilation, and, what are of the highest importance, spacious airways.

I believe that, notwithstanding the great quantity of air which

we find in many of the collieries, a large addition could be made to it by due attention in this respect.

As regards the liability to explosion from blowers or "bags of gas," no amount of ventilation can prevent it; the only safeguard against such accidents consisting in the constant and exclusive use of safety lamps in the whole of the working places and returns, naked lights being confined to rolley ways. In fact, the probability is, that the greater the ventilation under such circumstances, the greater will the explosion be, on account of the more rapid and extensive formation of explosive compound.

To the safety lamp, then, alone must we look for the prevention of accidents in mines subject to sudden outbursts of gas, in which we may include all which are termed fiery mines.

The only method of preventing accidents arising from neglect of doors or injury of stoppings is, to have an active and intelligent superintendence over such matters. There are, or ought to be, in all fiery mines especially, overmen; who, if they cannot immediately detect any deficiency in their air current, are totally unfit for their situations.

An accident may happen to a safety lamp from a fall of stone; and, as far as possible to prevent this, the lamps should be used under strict regulations, which should be placed in the hands of the workmen and exposed in various places about the works.

By far the greatest fatality consequent upon explosions of fire-damp arises from suffocation occasioned by the after-damp.

Choke or after-damp consists by weight of 22 parts of carbonic acid, 18 of steam, which is condensed, and 112 of uncombined nitrogen; therefore we may call it more correctly a compound of 22 carbonic acid and 112 nitrogen. The specific gravity of such a gas will therefore be 1·066, or so little above that of common air that it may be assumed to form a uniform mixture with it.— Williams's Combustion of Coal.

The derangement of the air stoppings resulting generally from an explosion, causes the air to escape from the downcast to the upcast shaft by more direct channels than the workings where the accident has occurred, the consequence of which is, that in most cases, before the ventilation can be restored, the unfortunate sufferers have ceased to live.

The modes of operation which appear practically (at least to a great extent) to remedy this evil consist in having, when such

an arrangement can be effected, the downcast and upcast shafts at opposite extremities of the workings; or in having distinct pairs of drifts for intakes or returns, these only being communicated together where rendered absolutely necessary; or, which amounts to the same thing, and possesses the advantage of applicability to existing and extended workings, in having the main returns driven in an adjacent seam of coal, when there is such at no great distance from the working seam. All the necessary artificial barriers between intake and return air courses should, of course, be of the most substantial description. By such precautions as these the force of a blast, by being more confined, might be more powerful; but this possible disadvantage would be many times overbalanced by their certain value in the facility they would afford to the speedy restoration of the circulation of air. Inundations may happen from one or other of the following

causes:

By incautious workings beneath seas or rivers;

By communication with drowned workings;

Or, by the working out of pillars under drowned wastes. With regard to the safety or otherwise of working beneath masses of water, this must altogether depend upon the situation, the strength and the nature of the superincumbent strata. There may be no danger in working within 20 fathoms of such waters, leaving proper pillars, the removal of which is, of course, out of the question. In the approach of drowned wastes, borings must always be made.

With regard to the other accidents arising from falls of stone, breakage of ropes, or derangement of machinery, they fall in a great measure within that category to which we must continue to a greater or less extent liable, in proportion to the number of people employed, and the amount of work they perform. There is no doubt that many accidents might have been, by proper precaution, avoided, but when we reflect that their causes are so numerous, we may well imagine, that even by the most careful, some circumstance, occasioning an accident, may have been overlooked.

All that can be done is, for every one in his own department to give the most unwavering attention to his duties, so that if, notwithstanding this, any accident should occur, he may be clear of that most severe of all punishments, self-condemnation.

In every colliery where inflammable gas is met with, a barometer ought to be placed near the shaft, and a daily register kept of the height of the mercury.

It may be stated, in conclusion, that few accidents need happen if we avail ourselves to the utmost of those appliances of mining now in our possession. The ventilation we are now able to establish, although there is no doubt but that, in the course of a few years, we shall see it largely increased, is sufficient for most cases, if not for all. Casualties of explosion, so long as unprotected lights are used in the working of fiery mines, will inevitably occur. The machinery of mines, in proper order is safe, so far as the dependence to be placed on the strength and soundness of materials can make it; and ordinary accidents must be averted by carefulness in the general system pursued in carrying on the working of the mines.

ON BORING AND BORING APPARATUS.

Boring is an art that is very imperfectly understood, even by those connected with mining, it is also an art of great value and of no little degree of antiquity, but until within a few years it has not received that degree of attention it practically merits. It is surprising that in this country so little attempt has been made to improve and raise into a science the practice of boring.

Boring is chiefly employed in searching for coal and ironstone; but, whether applied to the discovery of beds of coal, ironstone, marble, clays, salt, gypsum, limestone, slate, springs of medicinal waters, or water for domestic purposes, brine springs, or even the existence of combustible gases, it must be conceded that the development of an art which must increase our facilities for the attainment of such information, is of great practical importance.

In all these respects we are thrown each year still more on the art of the Borer, by which we see through the earth's crust. There are few departments of engineering towards which so many paths of science tend; there are few operations of a mechanical kind, which require the union of so much ingenuity, patient observation, and unflinching perseverance combined.

I will now proceed to describe some of the patents and principal processes practised in England, France, and Germany:

Among those who have improved the form of the cutting tools, we may mention Mr. Ryan, of England, who, about the year 1790, invented a tool by which cores or solid portions of the strata of the size of the bore-hole might be extracted, as well as Mr. J. Good, who in 1823, took out patents for various arrangements of this kind. Robert Breart, 1844; Wm. and Colin Mather, 1845; Wm. G. Gard, 1847; Charles Gotthelf Kind and Charles Alexis de Wendel, 1850; William Edward Schottlander, 1852; John Worthington and Fennel Allman, May, 1854; and