Messrs. Faraday and Lyell to be impracticable, is not likely to be controlled by a government inspector of mines. We have often felt oppressed and overpowered at the thought, that the mightiest efforts of man could not prevent these awful explosions, which cause such a sacrifice of human life. If it were possible to get at the immediate cause, some hope might be entertained of at least mitigating the evil; but from the scene of those accidents no one has ever returned to tell the truth.

"The system of ventilation pursued at the collieries in Northumberland and Durham, where most of these explosions occur, is of the most perfect and complete kind, and entirely in accordance with the principles of scientific truth. But, however sound the principles on which the ventilation is conducted, practice declares that there is a limit to the distance to which atmospheric air can be conveyed with safety underground, from the impurities it mixes with on its way; and however much the question may be avoided, by those who have capital invested in the deep collieries, to this it must come at last,more openings must be made from the surface; more pits must be sunk. The question must be brought to this practical issue,whether is capital or human life to be sacrificed? and when it does appear in this shape before the British Parliament, we do not fear the result.

"It is stated by Messrs. Faraday and Lyell, in their report on the explosion which occurred at the Haswell collieries in 1844, that 'when attending the late inquest, we were much struck with the fact, that more than half of the pitmen who gave evidence, were unable to write, or even to sign their names as witnesses.'

"It is a well ascertained fact, that accidents from fire damp have generally occurred with a low barometer; and when we consider that a fall to a very small extent will render a place, which it was safe to work in at night, entirely unsafe and dangerous in the morning, we cannot help feeling that there is something grievously wrong in allowing men, who cannot write their names, to have any thing to do with ventilation at all.”

The subject of Ventilation of Collieries and the nature of firedamp being of such great importance, it is hoped the following extracts on the subject from the London Mining Journal, Nov. 1853, may not be uninteresting.

On Ventilation of Collieries.

"The following epitome of that portion of the evidence given before the Parliamentary Committee of England by the government inspector, Mr. Dickinson, contains some valuable information in relation to colliery operations. Ventilation formed of course a most important element in the inquiry of the committee, and in its consideration are necessarily comprised the natural differences in roofs, the attendant dangers, and the most improved and secure methods of underground working, in its several branches and details. In his

testimony, Mr. Dickinson, the government inspector, recommends, in fire-damp mines to drive on the galleries to the extremity of the mine, and to work the coal backwards, as this insures a permanent air-way at all times; and he would prefer this system, whether the seam was perpendicular or horizontal; conceiving that there are no greater difficulties in ventilating a mine with air-ways in solid coal, than in air-ways maintained by gobbing—that is, in the refuse or rubbish thrown back into the excavations remaining after the removal of the coal. There is, besides, in his view, no liability to leakage, if the air ways are in the solid coal; and liability to leakage is avoided by driving out the level to the extremities, and working the coal backward. Mr. Dickinson is very decided in his approval of the longwork in collieries; and while he condemns the old system, as creating a series of unsightly caverns, he says, 'It is worthy of remark, that there is no instance that I have heard of, where long-work has been introduced, that that system has been abandoned and the old system. again resorted to.' He admits, that, in the beginning of working long-work, the first weight of the superincumbent strata on the face of the work, makes it dangerous for the workmen, and may crush the coal; in the course of a few days, however, after the first subsidence has taken place, the roof subsides regularly behind, and there is no more difficulty. He states that the workmen have sometimes abandoned the work until the first subsidence has taken place, and that where long-work has been attempted to be introduced into new collieries, by persons who did not understand it, when this first weight has been coming on, which is the critical weight, the system of longwork has been frequently abandoned; had they however waited until the subsidence had taken place, their efforts might have been successful.

"He observes that the great difficulty is with the workmen. He considers the long-work much better for ventilation, as in working pillar and stall-work, a number of galleries are left open, and all those galleries require to be ventilated; while, with the long-work you have simply the working face open, you leave an intake gallery for the air to go into, it then passes up the face of the work, and returns by the return drift; while with pillar and stall-work you have a number of galleries which require to be ventilated; and he further states, as a reason for preferring the long-work as to ventilation, that the distance which air travels in long-work is shorter than that which it travels with pillar and stall-work, because you have only the intake gallery, the face of the work, and the return air course to ventilate, and as there is no pillar and stall-work the air is not to be coursed through. The evidence explains that in long-work there is simply a current of air going from the down-cast shaft to the face of the work, running along the face of the work, which is only a channel 6 or 7 feet wide, and returning by a drift to the upcast; while with the pillar and stall-work, if you have 20 stalls, you may split the air into 4 parts, each current of air, or each fourth part, has to course through 4 stalls, with a door between each stall; and

therefore, each current of air has to pass up one half of the stall and down the other. In the old system there is also a risk of doors being left open, while in the long-work there are no doors except there be main doors; and where the face of the coal gives vent to an enormous quantity of gas, contingencies arising out of doors are very much fewer than in pillar and stall-work, as the air is all passing up the particular places where it is required. Mr. Dickinson clearly intimates his opinion that the long-work system is in all cases more economical and safe than the pillar and stall system, and that many persons work long-work both with good and bad roofs. He further remarks, that in working the thick coal of Staffordshire, where the top part of the seam is worked first, and there is nothing but the old gob for the roof of the second working, Mr. Gibbons, whom Mr. Dickinson considers authority in these matters, having worked the coal for several years under the long system, says he prefers a bad roof to a good one. This is explained thus: that a hard solid rock for a roof which will not break, is apt to crush your coal, and is attended with more danger than would otherwise be met with if you had a tender roof. He then explained that he had seen a modified system of long-work which, although not the ordinary system of long-work, is called long-work, in South Wales, practised very successfully under a quor roof. It is by driving a stall 8 yards wide, and bringing back the same width of pillars. All the coal is obtained in that working; and perhaps it is the only successful working of coal that there is in South Wales, for all the rest, under the bad roofs, is attended with a very considerable sacrifice of pillars; and he observed that his remarks applied to the cleanness of working, but generally equally to the ventilation."

Mr. Dickinson further stated, "that it was a general rule that a plate roof, which usually bends rather than breaks at first, is one of the best roofs for working long-work, and that long-wall work is quite applicable to it; he does not, however, seem to approve of the usual way in Staffordshire-that is, of working the upper portion firstbut thinks that the best way is to work the lower part first, taking care to pack the gob very tight with rubbish. He then proceeded to detail the plan on which he would commence the long-work system. He would keep the lower levels in advance of the upper, for it was generally found that, in attempting to keep the upper levels in advance of the lower, there is a tendency to throw the weight of the roofs on the face of the work, which makes it more dangerous for the men, and also tends to crush the coal; even where the pit is sunk to the bottom of the seam, as the weight always tends to the dip, he would start the drifts, so as to keep the lower drifts in advance of the upper, and throw the weight of the work on the gob and not on the face of the work.

"After opening the pit, and getting the ventilation connected between the down cast and the up cast, if it were not a fiery mine, he would breast all the coal forward, carrying the airing along the deepest level, and bringing it back along the upper level, working straight

before him. If it were a very fiery vein, he should recommend driving out the galleries to the extremity, and sinking backward instead of forward, so that the gas would be left behind, and the ventilation maintained by having the galleries in solid coal, and not subject to leakage through the gob. He would take the breast of coal forward and leave the gob behind. Mr. Dickinson then explained the mode of working which he would recommend; it is not new to experienced coal mining engineers, nor indeed to many working miners, but we have been thus minute as coming from a government inspector, to whose care a very extensive mining district is confided, and as it may be supposed to bear with it the stamp and weight of official authority.

On the Nature of Fire-Damp. From London Mining Journal, Dec. 1853.

و,

"Mr. Dickinson entered on another branch of the subject, and observed in answer to a question, No. 98: An imperfectly ventilated goaf is about the most dangerous thing you can have in a collierythat is where the fire-damp is mixed with fresh air enough to bring it to the explosive point. When the goaves are not at all ventilated, the fire-damp in them is generally too pure to be explosive; and I have known cases where a goaf which has been full of fire-damp, has fired along the edge where it has been mixed with fresh air, but there not being sufficient air with the fire-damps in the goaf, it has merely been an explosion for the width of a yard or two along the edge. Mr. Dickinson stated that the air may be so foul as not to be inflammable, but then when there is a strong admixture of fire-damp it is not respirable. He had in his district two men who were suffocated by inhaling a strong admixture of fire-damp. The effect is to quicken the pulse; he stated that he had tried his own pulse before going in -it was 78 at entering this admixture of fire-damp, and after being in for a few minutes, it ran up to 84; he tried a manager's pulse and it ran up from 80 to 84; he also tried a fireman's pulse, it was at the very unusual height of 120, and it ran up to 126. A person is only enabled to remain in this gas a few minutes, otherwise he would soon fall down and expire, and this gas was explosive at the edges. Mr. Dickinson then stated that in order to be explosive there must be an admixture; an explosive mixture is, he should think, 1 part of gas and 7 of air-and when asked 'When does it cease to be explosive?' his answer was, I think at about 15—that is, 15 parts of atmospheric air to 1 of fire-damp.' We regret that the information which Mr. Dickinson supplied to the Committee was so defective, throwing no new light whatever on the subject—as after an interval of 40 years, which have witnessed a marvellous advance in philosophic knowledge, much might have been anticipated from more accurate analysis and more perfect apparatus. Specimens of fire-damp had been sent from various collieries to Sir Humphrey Davy at that period, for examination and experiment, and he found that the pure sub-carburetted hydrogen, commonly called 'fire-damp,' requires twice its bulk of

pure oxygen gas to consume it completely, and that it would, for the same effect, require about 10 times its bulk of atmospheric air, as this volume of air contains about two volumes of oxygen."

"Ten volumes of atmospheric air, therefore, mixed with one volume of sub-carburetted hydrogen gas or fire damp, form the most powerful explosive mixture. If either more or less air be intermixed, the explosive power will be impaired, until 3 volumes below, and 3 above that ratio constitute non-explosive mixtures, that is, 1 of pure firedamp mixed with either 7 or 13, or any quantity below the first or above the second number, will produce an unexplosive mixture. Davy drew a conclusion that fire-damp would not explode when mixed with less than 6 times, or with more than 14 times its volume of atmospheric air. Scientific men have for a long time been acquainted with these results, but as the experiments which led to them would appear to have been made with gas, brought in some instances from distant collieries, subject to the effects of time and carriage, and as Mr. Dickinson had ample means of procuring the fresh gas on the spot, and has, at his command, the improved appliances of modern science, we confess we would have been better pleased if he had enlightened the committee by evidence of his own philosophical skill. According to Davy, it is the carbon the fire-damp contains, which enables it to emit more light during combustion than pure hydrogen. 100 cubic inches of fire-damp weigh about 17.2 grains; its specific gravity compared with atmospheric air is 0.554. It consists of 4-3 grains of hydrogen gas, combined with 12-9 grains of carbon. A most important fact seems, however, to have been almost wholly overlooked. Davy also ascertained that 1 volume of carbonic gas to 7 of an explosive mixture, composed of fire-damp and atmospheric air deprived it of its power of exploding altogether."

"We are aware that in some collieries, the fissures in the coal resemble natural gasometers, and that even if a mine be cleared one day of inflammable gas, it often fills like a well the next. When, however, we know that carbonic acid gas is, in artificial formation, the easiest procured of all gaseous product, and when we find that the injection of it in large quantities has been recently applied, with complete success, to extinguish fire in mines, it may not perhaps be a very extravagant speculation to suggest that it might be hereafter successfully combined by a simple process with the admixture of firedamp and atmospheric air, so as to render that admixture unexplosive, and consequently harmless, provided the combination would not itself fatally affect the respiratory organs of human life.”

"When we reflect upon the extraordinary and almost marvellous achievements which human perseverance and scientific skill have accomplished in our times, we see nothing to discourage the experiment as visionary or hopeless. The safety lamp was itself the result of clear conception, with careful and cautious investigation; it owes its present perfection to the improvement of time and experience, but still it has not proved a certain or complete protection. The Middle Dyffryn Colliery is a remarkable instance. That colliery