130 _______________________________________________ Classed according to kinds of power, the particulars are:— Horse-power. Steam engines, reciprocating ............ 5,316 Internal combustion engines (gas, oil, &c.) 16 Water power............................ 12 Total .............................. 5,344 source of loss to the pits, though the total deliveries showed an increase over 1911. In the first 11 months the syndicated pits raised 86 million tons of coal, or 308,000 tons per working day, an increase of 6’5 per cent.; and the calculated distribution amounted to 69| million tons, being approxi- mately 95| per cent, of the participation and 81 per cent, of the output. The effective distribution of coal, coke and briquettes was 55 million tons, of which 48 million tons were for account of the Syndicate. Coal Market in Upper Silesia.—The*activity of the demand continues to task the resources of the pits, especially in view of the scarcity of railway wagons, which is not yet over, though the conditions in this respect are beginning to improve. A memorial was recently addressed to the Minister of Public Works, pointing out that even as late as December the shortage of wagons still amounted to about 40 per cent. It is certain that this state of things has caused great loss and inconvience, both to the producers and consumers of coal. The iron industry, for example, has been complaining for weeks about insufficient supplies of fuel; but, taking all things into consideration, the situation cannot be considered bad, the deliveries for the year just elapsed having exceeded those of the previous year by nearly 4| million tens. Industrial and coking coals are the most active, but there is a large sale for gas coal, and house coals are doing well in spite of the mild weather. The coke market retains its satisfactory features. The firms making returns also stated that they possessed dynamos of 239 kilowatts capacity, driven by steam engines. The capacity of these dynamos should not, of course, be added to that of the engines owned. What the information shows is that (taking 746 kilowatts as equivalent to 1,000-horse power, and allowing about 10 per cent, for loss of energy in conversion) about 7 per cent, of the engine-power belonging to manufactured fuel factories was required for driving dynamos for the production of electric power and light. A complete statement of the amount of electric energy generated by those dynamos cannot be made, but manufacturers with dynamos of 101 kilowatts capacity stated that 237,000 Board of Trade units of electricity were generated. About 3,000 Board of Trade units of electricity were purchased and used for lighting and power. (To be continued). CONTINENTAL MINING BOTES. ____________ ________ _________...... Germany. Output of Fuel.—The following shows the production of various classes of fuel in November 1912 and the eleven months ended therewith :— November. January-November. 1911. 1912. 1911. 1912. Tons. Tons. Tons. Tons. Coal...........13,838,751...14,805,443...147,309,135 ..162,209,627 Lignite ...... 6,788,133... 7,558,561... 67,081,079... 75,218,408 Coke........... 2,215,273... 2,596,768... 23,102,454... 26,435,461 Coal briquettes 433,018... 448,329... 4,583,678^ 4,870,954 Lignite ditto... 1,549,012... 1,671,265... 15,455,110... 17,420,149 .Exports and Imports of Fuel.—The following table shows the exports and imports of fuel during the first eleven months of 1912:— Imports. Exports. "1911. 1912? 1911. 1912?^ Tons. Tons. Tons. Tons. Coal............. 9,958,356... 9,480,998...21,806,125...28,275,622 Lignite........... 6,463,976... 6,704,937... 52,582 . 50,395 Coke............. 549,012... 544,304... 4,079,834... 5,321,987 Coal briquettes... 88,370 .. 46,438... 1,773,265 .. 1,929,259 Lignite ditto.... 107,614... 121,271... 463,642... 549,421 “In the 11 months 8,199,423 tons of British coal were imported, as against 8,571,015 tons in the corresponding period of 1911. In the month of November, however, the imports of British coal amounted to 886,883 tons, as against 806,186 tons in November 1911, whilst 1,002,271 tons of coal in all were imported, as against 946,070 tons. The entries of British coal at ports in the Baltic showed a remarkable falling-off in November totalling 236,710 tons, as against 418,561 tons, the imports at Stettin and Swinemunde being 66,905 tons, as against 238,102 tons. The imports of other classes of fuel were as follow in November:—Lignite, 676,065 tons (650,105 tons) ; coke, 50,130 tons (51,362 tons) ; coal briquettes, 5,167 tons (6,819 tons) ; lignite briquettes, 16,276 tons (14 216 tons). Exports in November were as follow :— Coal, 2,551,839 tons (2,560,572 tons) ; lignite, 5,629 tons (4,216 tons) ; coke, 505,844 tons (361,411 tons) ; coal briquettes, 168,123 tons (177,798 tons) ; lignite briquettes, 73,885 tons (56,534 tons). Exports of coal to Belgium and France declined slightly in November, and there was a considerable drop in those to Holland, the principal increases being to Italy, Switzerland and Austria-Hungary. There was a large advance in exports of coke to Belgium, France and Italy. Official Coal Prices on the Dusseldorf Exchange.—Gas and open-burning coals : Gas coal, summer months 12-13 marks per ton, winter months 13-14 marks; producer coal, 12 50-13 50 marks; open-burning gas coal, through-and- through, 1150-12 50 marks. Bituminous coals: Through- and-through, 1125-12 marks; best mixed, 12 50-13 marks; coking coal, 12 25-13 marks. Lean coals: Through-and- through, 10 50-12 marks; best mixed, 12*75-13’25 marks; anthracite nuts II., 21’50-25’50 marks. Coke: Foundry coke, 18-20 marks; blastfurnace coke, 15*50-17’50 marks; broken coke I. and II., 20-23 marks; briquettes, 11-14’25 marks. Ruhr Coal Market.—The present condition and future prospects of the market are favourable, the only adverse factor being the continued shortage of railway wagons. Looking back over the past year, it may be regarded as very satisfactory, certain unfavourable factors apart. The demand began to improve early in the year, favoured by the busy state of the iron industry and the miners’ strike in Great Britain, which latter restricted the imports from that country until April. A brief interruption to the general activity was caused by the local strike in March, but after a certain slackness in the summer, a renewed activity set in during August and attained an unusually high level in September. In the later months, however, the scarcity of railway wagons proved a great hindrance to business andja January 17, 1913 ______________________________________________________________________ THE COLLIERY GUARDIAN. Letters to the Editor. _________________________________________________ The Editor is not responsible either for the statements made, or the opinions expressed by correspondents. All communications must be authenticated by the name and address of the sender, whether for publication or not. No notice can be taken of anonymous communi- cations . A.srepliesto questions are only given by way of published answers to correspondents, and not by letter, stamped addressed envelopes are not required to be sent. _________________________________________________ HOME OFFICE COLLIERY MANAGEMENT. Sir,—The action taken by the Home Office in regard to the Bentley Colliery (which the writer thinks he has seen described as “the one man Government”), is certainly extraordinary, and brings to mind an answer given by Sir Henry Hall when asked how a mine could be rendered perfectly safe. He replied that the only way to do so was to let it remain unworked. The country cannot afford to let her coalmines lie idle, and therefore, as some risk must be run in keeping them in operation, the exercise of common sense is also necessary to save the mining interests from frantic legislation. There was a time, not many years ago, when a mine with only 2J per cent, of firedamp in the air would have been declared free from gas, and shots fired ad lib., but now 2J- per cent, is dangerous. Why is 21 per cent, of gas in the ventilating current considered dangerous in places where there is no blasting, and only locked safety lamps of the most approved design are in use ? To explode a mixture of air and firedamp in such a mine requires that there must be a deficient safety lamp or an open flame of some sort, and lastly, more than 2j per cent, of firedamp. Have we then arrived at such a period of scare that a safety lamp of approved design is to be considered unsafe in an air current containing only 2J per cent, of gas ? If so, why make exhaustive tests on safety lamps ? The time is evidently fast approaching when we ought to abandon coal- mining and use oil, or try a well known savant’s idea, viz., to set the mines on fire, and use only the gases distilled from the coal. Not many years ago a paper was contributed to the Transactions of the Institution of Mining Engineers, giving the full details of a case in which coaldust was inflamed by a small hot and blazing piece of coke flicked off the lighted wick of a fireman’s safety lamp—the inference conveyed being that under certain not fully known conditions, a small open flame might fire a mixture of coaldust and air. Here, then, is another reason why air might be considered dangerous without the presence of either 2J or any smaller per cent, of firedamp. If the whole “ kick ” is at mines in which explosives are used, why draw the line at 2J per cent, of firedamp ? Ample proof has been given that coaldust and air without any admixture of firedamp may be exploded by the flame from a shot or an open light. In a paper contributed to the Institution of Mining Engineers, attention has been drawn afresh to the fact that the rock forming the roof of certain collieries may, in falling, cause sparks of sufficient intensity to ignite mixtures of air and firedamp. This is no new discovery, as experiments made many years ago in South Wales amply proved that gas could be thus ignited, but so far fortunately the Home Office has not compelled the mineowners to prevent falls of roof in the goaves. Let us also be thankful that up to now the Home Office has not directed the disuse of steel picks and shovels by coalminers, because of the sparks produced when these tools strike rocks, and which sparks the Home Office might think to be dangerous in an atmosphere containing 2| per cent, of firedamp. How to deal with gob fires is a kindred subject to the 2J per cent, firedamp puzzle. Some years ago a well-known mining engineer contributed a paper to the North Staffordshire Institute of Mining and Mechanical Engineers on the extinguishment of gob fires by filling the goaves with pure firedamp, and the idea worked satisfactorily in his case. This brings to mind the Bignall Hill disaster, which occurred whilst men were putting in fire stoppings. The conditions surrounding this disaster were that heating in the gob had been discovered in a part of the mine adjoining a fault, and where the coal was 20 ft. thick. The roof was “ weight- ing,” and fire stoppings which had been partially constructed in the roads as a precaution in case of emergency, were being completed, when gas and heat were suddenly forced out, slightly burning four men, and asphyxiating others. This was called an explosion, but no damage was done to the mine. For an explana- tion of what really happened we need only turn to Mr. J. R. R. Wilson’s evidence at the Cadeby inquest. He said a miner had related to him that one day whilst eating his “ snap,” there was a tremendous noise in the gob like cannons going off, and tongues of fire were forced out, over or through the packs around where the fire was thought to be incubating or had already incubated. The fall of roof at Bignall Hill was also close to a fault, as at Cadeby. At Cadeby no one was reported to have been burned. There was no ignition of coaldust in either case, and no explosion of firedamp. What probably occurred at the great Cadeby disaster is not difficult to imagine after the experiences above related. Just a few more restrictions and coalmining may become impracticable, even with electric safety lamps, which certainly have the advantage of not indicating to the miner whether there is or is not 2| per cent, of gas present in his working place. 930, Drake-street, James Ashworth. Vancouver, B.C., December 21, 1912. _________________________ COMPARISON OF RESCUE APPARATUS OF THE INJECTOR AND NON-INJECTOR TYPE. Sir,—Mr. R. Jacobson (agent for Messrs. Draeger, of Lubeck) dealing with Professor Cadman’s warning as to the danger of negative pressure in the injector type of apparatus, says that the positive type is no less dangerous because a leak in such allows oxygen to escape. I join issue with him over this. If there be the least leak in the injector type the negative pressure draws in the afterdamp containing carbon monoxide, which, in very low concentrations, is highly dangerous and gives no warning of its deadly presence to the wearer of the apparatus. In the case of the positive type, the oxygen is delivered into the breathing bag by a reducing valve at a rate of two litres per minute, and if there is any leak the breathing bag is not so well-filled as usual, and this gives the wearer a warning which he cannot fail to notice before he enters the dangerous atmosphere. There is no difficulty in protecting the face from heat in the case of one wearing the positive apparatus. A mica face screen, or mask, is often worn for this purpose. As to the cooling of the inspired air, this is a point which can be overcome in various ways, and I believe the makers of the “ Proto ” positive pressure apparatus are dealing with the matter. Leonard Hill. London Hospital Medical College, Turner-street, E., January 8, 1913. ______ Sir,—May I be allowed to supplement my letter of the 8th inst. ? When I first went under water with my self-contained respiratory apparatus in the diving tank at the old Polytechnic in Regent-street in the year* 1879, I had a considerable leak at the helmet, but this did not cause me the slightest inconvenience; it merely got rid of much of the nitrogen originally contained in the slack of the diving dress, &c., leaving me practically pure oxygen to breathe. Oxygen as now made contains a small percentage of nitrogen. Oxygen is absorbed by the blood in respira- tion, while the nitrogen is not absorbed ; therefore it is necessary from time to time to blow off gas from the breathing bag of the rescue apparatus for the purpose of getting rid of the excess nitrogen which would otherwise accumulate in the bag. Much less than a bagful of many of the poisonous