at this point two doors were blown into fragments, and the iron door-frames shattered as if a violent explosive had been fired directly into them. Traces of the explosion were found 1261 yards away, where a fall of roof took place, and here it was stopped by a wet piece of roadway 53 yards long.

The report says: "In view of this experience, your Majesty's Commissioners cannot doubt the possibility of an explosion from coal dust alone, even in mines where no gas has ever been known to exist."

III. A small explosion of fire-damp may originate a great explosion of coal dust. The first explosion may raise a cloud of dust, and this cloud may be ignited and explode, raising another, and so on.

On this point little real difference of opinion seems to exist. Two or three of the witnesses would not admit that coal dust could even carry on an explosion without gas, but the evidence, especially that on the Seaham explosion, 8th Sept., 1880, Risca 15th Jan., 1882, Alltofts 2nd Oct., 1886, Elemore 2nd Dec., 1886, and others, shows that gas played a very subsidiary part.

IV. That a mixture of coal dust and air, where mixed with a proportion of fire-damp too small in itself to be explosive, will produce an explosive mixture when brought in contact with a light, is capable of direct proof from experiment more readily than any other point of the coal dust theory. The experiments of Mr. Galloway and Professor Abel leave no doubt on this point. Two per cent. of gas will make a mixture of air and coal dust explode with a naked light, whilst in the absence of dust, six per cent. is necessary. All the witnesses except one agreed in admitting this danger, and as there is always some fire-damp present in the great majority of coal mines in the United Kingdom, this particular danger is a matter

of serious consideration. It is evident that any precautions taken with regard to shot firing would leave this source of mischief untouched, and it can only be obviated by provisions calculated to prevent the dust from rising, or to render it innocuous.

After reading the evidence, it is evident that the Commission could have no difficulty in arriving at the conclusions contained in the report. These were:

1. The danger of explosion in a mine in which gas exists, even in very small quantities, is greatly increased by the presence of coal dust.

2. A gas explosion in a fiery mine may be intensified and carried on indefinitely by coal dust raised by the explosion itself.

3. Coal dust alone, without the presence of any gas at all, may cause a dangerous explosion if ignited by a blown out shot, or other violent inflammation. To produce such a result, however, the conditions must be exceptional and are only likely to be produced on rare occasions.

4. Different dusts are inflammable, and consequently dangerous, in varying degrees, but it cannot be said with absolute certainty that any dust is entirely free from risk.

5. There appears to be no probability that a dangerous explosion of coal dust alone could ever be produced in a mine by a naked light or ordinary flame.

Having come to these conclusions, the Commission had, lastly, to make recommendations as to the best means to be adopted to minimize the danger. Mr. Woods alone would prohibit all shot firing, either by gunpowder or high explosives; but, as this would render it necessary to close some pits entirely, and seriously raise the price of coal, the Commission did not accept this view.

It being certain that gunpowder has some advantages over high explosives, the Commission only recommend

that its use should be forbidden in certain cases, especially in fiery and dusty mines.

The use of high explosives, which are comparatively flameless, is advocated. The objections on the ground of the poisonous nature of the fumes produced do not seem to be well founded. A Lancashire collier was said to have been poisoned by the gases from roburite, but the Committee of Inquiry, on which Professor Dixon and two medical men took part, decided that, though roburite itself was a strong poison, the fumes from it, when strict care was exercised, were not more deleterious than those of other explosives.

Removal of Dust. Though this is recommended where there are great accumulations of dust, it cannot be done to any great extent.

Watering. This is evidently the most practical precaution, but various methods of carrying it out are suggested. It is largely adopted in Durham, South Wales, Staffordshire, Yorkshire, and Derbyshire. In other districts there appears to be little damping.

It has been objected that watering would loosen the strata and bring down the timbers and roof, and lift the floors. This would, however, only happen if too much water was used, whilst watering would have an additional advantage in lowering the temperature of deep mines, and so rendering them more comfortable to work in.

Watering by means of spray seems to be the most. effectual means of damping the dust, not only on the floors, but also that on the sides and roofs of the roadways. The requisite pressure may be that of the water itself, or obtained by means of compressed air.

The Commission, therefore, recommends that the Inspector should have power to order watering to be done, or to insist on more efficient means being adopted where,

in their opinion, those in use are inefficient. conclude with the following suggestions:

They

1. That the firing of shots should take place between the shifts, and when the majority of the men are out of the mine

2. Where general watering is not prescribed by the Inspector, that the roads on either side of the place where a shot is fired, should be thoroughly wetted for a space of at least thirty yards—

Lastly, that large accumulations of dust, whether on the floor or roof, should not be allowed to remain.

It now only remains for legislation to enforce the recommendations of the Commission, to reduce the number of those fearful explosions which render the life of a collier more precarious than that of a soldier, and to illustrate the benefits which the researches of science confer on humanity.

121

TRADE GUILDS.

BY FREDERICK W. EDWARDS, M.S.A.

In previous papers read before this society from time to time, and published in its Proceedings, I endeavoured to trace in special detail the growth and position of technical, commercial, and industrial education. The pursuit of the necessary knowledge of these important phases of practical instruction resulted in the accumulation of a considerable amount of interwoven matter of so interesting and generally unknown a character, that I now venture to bring that portion before you relative to the kindred subject of Trade Guilds, particularly those which sprang up and flourished so extensively in England during the middle ages. I propose to briefly survey their general origin, constitution, development and effect, concluding with a short reference to the objects, customs, ceremonies, characteristics, and influence of a few of these ancient, powerful, and wealthy commercial institutions.

Medieval Guilds present a close analogy to the collegia opificum which existed under the Roman Empire. These were associations arising out of the urban life of the period, the primary objects of which were common worship and social intercourse, their secondary objects being the protection of the trades against unjust taxes, and their internal regulation. They also served as burial clubs, defraying the expenses of burial and funeral sacrifices for deceased members, in some cases out of legacies left for that purpose. It has been suggested that Mediæval