March 30, 1917. THE COLLIERY GUARDIAN. ______________________________________________ 627 due to other causes; too high a temperature of the workings or carbon monoxide being the most usual. In any case, the presence of the disturbing agency would not have been detected by the use of oil lamps. Indeed, the author has many times seen men fall like flies in a place they had considered safe, because their oil lamps gave no indication of anything abnormal in the composition of the atmosphere. The supposed danger from the use of acetylene lamps where blackdamp may be encountered has caused their use in pillar work and in robbing to be discon- tinued to some extent, thus exchanging a danger of the imagination for a very real peril. Those familiar with the coal mining industry know what a curse miner’s asthma has been. If not caused, it is at least aggravated, by the greasy soot and oily emanations given off by the oil lamp. Now, these foul vapours are at their worst in pillar work and in robbing where the ventilating current is apt to be at its lowest ebb, and where blackdamp is obviously most likely to be encountered. Hence, as a result of trying to safe- guard the miner against the hypothetical danger—of a combination of blackdamp, the acetylene lamp, and his own stupidity—we expose him to the very real and pressing danger of miner’s asthma, against which the most careful and most thoughtful is helpless. The deepening of mines, and the increased length of airways, together with the greater attention now given to the danger of gas and dust explosions, have all tended to increase the number of safety lamps in use. Safety lamps may be divided into two classes: the electric cap lamp, and the flame safety lamp. The electric cap lamp is a development of the last seven or eight years, and its growth was very lucidly traced by Mr. J. T. Jennings in a paper read at the 1916 meeting of the Coal Mining Institute of America. European practice has tended toward the development of an electric hand lantern. Because of the more general use of flame safety lamps in Europe, the mine workers were satisfied with this type, being accustomed to the inconvenience of hand lamps. In the United States, however, conditions are radically different. The miners are, as a general rule, accustomed to open lights worn on the cap, and rebel at the inconvenience and inefficiency accompanying the use of the electric hand lantern. Hence, when an electric miner’s lamp was developed, it became essen- tial that it should be such that the efficiency and con- venience of the cap lamp would be retained. Progress was made along these lines, with the result that the present very convenient equipment has been developed. It is remarkable that so complete a standardisation in general design as is now found among the product of the numerous manufacturers of this type of lamp should have been possible. The credit for this should be given to the U.S. Bureau of Mines, which has worked hard and faithfully with the manufacturers of electric cap lamps for the past four years or so, and has had a very definite vision of what such a lamp should be. The result of this pre-natal influence is a startling similarity in the various equipments offered to the mining industry. While this method has perhaps sacrificed a little individuality, it has undoubtedly increased the average excellence of the product, and made the whole industry more robust by weeding out the abnormalities. Many of the underwriters of insurance under the Employers’ Liability Act have shown a marked pre- ference for the electric cap lamp when compared with the flame safety lamp. This preference has led to the penalisation of companies using the flame safety lamp, to the extent of 11c. for each 100 dols. of pay-roll, whereas, were electric cap lamps installed, this penalty would be wholly removed. This premium has led to the installation of many electric cap lamps. This lamp throws its light into the plane of vision of the wearer so that its light is efficiently utilised. It leaves the miner’s hands free, and the light requires no attention; indeed, the outfits are so arranged and locked that it is impossible for the wearer or any unauthorised person to tamper with them. There is no fire risk with these lamps, and we are assured by the Bureau of Mines that the danger of their origi- nating a gas explosion is practically nil. These are also the safest of all lamps with which to handle explosives. They have three chief disadvantages: their upkeep is high, the flux of light they furnish is not so great as it should be, and their wearer is in absolute ignorance, so far as the lamp enters into the matter, of the nature of the atmosphere surrounding him. It is very probable that the next few years will see these faults abated to a considerable extent. That the flame safety lamp should be so old, so widely used, and so little improved in all its years of service reflects but scant credit upon the human mind. To all intents and purposes we still have Sir Humphry Davy’s invention in actual use, development having practically stopped after introducing the use of a cylinder glass to surround the flame. In the United States the bonneted Clanny and Wolf type are prac- tically standard except where heavily pitching veins are encountered, as in the Schuylkill anthracite dis- trict. Here, because of its lightness and the con- venience with which it is handled on the pitches, the old Newcastle Davy is still supreme. The flame safety lamp is principally handicapped by the meagre light it gives. Its use is absolutely essen- tial as an indicator of the quality of the mine air in all gaseous mines, and the author would suggest that even in non-gaseous mines, where electric cap lamps have superseded open lights, the installation of a number of flame safety lamps would be an added safe- guard. The principal difficulty in the use of the flame safety lamp as an indicator of atmospheric conditions, where electric cap lamps’ are relied upon for illumina- tion, is that unless the flame lamp is the source of light,,it will come to hang unnoticed on the miner’s belt or be left neglected in a corner of his working place. In other words, unless his attention is auto- matically called to it from hour to hour, he will, in the long run, cease to note its warnings. While the variations of the Davy principle on which flame safety lamps are constructed have been endless, these variations have been slight, and the principle has not been diverged from with any success. As a result, the flame safety lamps in actual use are of two very similar types, the Clanny and the Wolf, ignoring the Davy lamps used in the southern anthracite dis- trict of Pennsylvania, for these will soon disappear. With the design of the lamp fixed, there is but one variable to consider, and that is the fuel burned. Even this disappears in the case of the Wolf lamps, as these will only function with naphtha whose composition may vary within but narrow limits. With the Clanny type lamp, however, a wide variation in the nature of fuels is possible. Among these are sperm, pea-nut, lard, rape, seal, cotton seed, and mixtures of these with mineral burning oils. The author has spent much time in investigating the question of improving the quality of safety lamp oils, and has met with some success in this direction. It has been found that some of the most costly and highly-prized safety lamp oils were really inferior to mixtures containing high pro- portions of high-grade mineral burning oils. These mixtures burn with a whiter flame, give appreciably more light, do not crust the wick, and are much cheaper than the standard safety lamp oils. Another type of lamp that holds out promise for the future is the acetylene safety lamp invented by Mr. T. M. Chance, of Philadelphia; but as this lamp is not yet a commercial fact, little can be said of it defi- nitely. It would seem, however, that it combines the safety and indispensable gas-detecting properties of the flame safety lamp with many times the illumi- nating power of the electric cap lamp. Table A below contains data that may make some of the above statements more intelligible. These data have been accumulated during the past eight years, and are general averages. The photometric determinations were made upon a United Gas Improve- Output of Coal at Mines in the United Kingdom in the undermentioned Periods of the Years 1913, 1914, 1915 and 1916; also the Quantities Exported and Available for Consumption. Half-year ended I I j Output.*' Exports (including the coal equivalent of coke and manufactured fuel). Quantities available for consumption.! Quantity shipped for use of steamers^ engaged in foreign trade, and included in the preceding column. June 30, 1913§ 145,561,000 37,279,000 108,282,000 10,087,000 December 31, 1913§ i 141,851,000 40,028,000 101,823,000 10,945,000 June 30, 1914 ; 139,994,000 36,390,000 103,604,000 10,182,000 December 31, 1914 ! 125,649,000 26,068,000 99,581,000 8,354,000 June 30,1915 ’ .. 127,620,000 23,595,000 104,025.000 7,400,000 December 31, 1915 j 125,559,000 22,727,000 102,832,000 6,231,000 June 30, 1916 : 128,135,000 20,932,000 107,203,000 6,578,000 December 31, 1916 i 127,711,000 21,081,(00 106,630,000 6,410,000 Year 1913 287,412,000 77,307,000 210,105,000 21,032,000 Year 1914 1 265,643,000 62,458,000 203,185,000 18 536,000 Year 1915 ' 253,179,000 46,322,000 ’ 206,857,000 13,631,000 Year 1916 ' 255,846,000 42,013,000 213,833,000 12,988,000 * Including coal used for colliery purposes. t Including coal for the use of the Admiralty, or for use as bunker coal in merchant ships. X Not including steamers taken up by the Admiralty. § Output estimated from the ’* Mines and Quarries” Return issued by the Home Office, and from information supplied to the Coal Mining Organisation Committee. _________________________________________________________________________________________________________________ ment Company 60 in. bar photometer. The photo- metric standards used were 10-volt tungsten lamps, prepared and calibrated by the National Lamp Works, and standard sperm candles. At times a secondary standard was used, consisting of a long-time kerosene burner, similar to that used in railway signal practice, standardised against one of the primary standards noted above. Table A. Candle-power of Various Types of Portable Miners* Lamps. Candle- Cost per power. shift. Cents. Miners* open oil cap lamp........... 1'50 ... 2’4 .................. .................. Miners* open acetylene cap lamp ___ 5’00 ... 1’5 Electric cap lamp.................... 1’10 ... — Davy safety lamp...................... 012 ... — Clanny safety lamp................ 0’35 ... — Wolf type safety lamp ............. 0’65 ... — Ackroyd and Best safety lamp....... 1’10 ... — T. M. Chance acetylene safety lamp... 3’80 ... — Note.—The above candle-powers are in no sense maximum, but are the average values over the field illuminated by the lamp in question and have been obtained from many determinations. These are the values that may be expected to be realised in practice under working conditions. It will be noted that no estimate of the cost per day of electric cap or flame safety lamps is given in the table. In the writer’s opinion, the modern electric cap lamp has not been in use long enough for an intelligent opinion of its upkeep cost to be formed. Moreover, the labour charge on both the electric cap and flame safety lamps is so large and varies so much with the size of the installation that such figures as could be given would have but little meaning. Conclusions. (1) The open oil lamp has outlived its general use- fulness. It still has a field, however, in special cases, such as those of drivers, motormen, trip runners, and the like, who are obliged to work in swift air currents. (2) The use of the open acetylene lamp is growing in all non-gaseous mines because of its cheapness, the powerful light it gives, its reliability in the presence of blackdamp, and its freedom from soot and noxious vapours. (3) The electric cap lamp is best adapted to use in gaseous mines. Its flux of light is superior to that of the flame safety lamps now in use. Moreover, as it leaves the hands free it is more convenient than the flame safety lamp. Under especially drastic condi- tions in non-gaseous mines, where the fire risk is unreasonably high due to peculiar Jocal conditions, its freedom from fire hazard recommends its use. In all gaseous mines its use must be accompanied by that of flame safety lamps, in order that the condition of the atmosphere may at all times be known in all parts of the mine. Where it entirely replaces open lights in non-gaseous mines, it is imperative that a few flame safety lamps be supplied along with the electric cap lamps for the same purpose. (4) The flame safety lamp should be used in all gaseous mines irrespective of the use of electric cap lamps. These lamps form in themselves the best and most trustworthy gas detector yet devised, and their presence is absolutely essential to the safe operation of such a mine. Even in non-gaseous mines, where electric cap lamps have replaced open lights com- pletely, it is good policy to have a liberal proportion of flame safety lamps. The flame safety lamp is doubt- less an unsatisfactory working light, but its role is twofold. It may be used as a working light, but it must be used as a gauge of the safety of the mine atmosphere. (5) There is a new acetylene safety lamp that gives promise of being an admirable working lamp, as well as an excellent firedamp and blackdamp detector. _____________________ COAL OUTPUT IH 1916. A return is published by the Board of Trade showing the estimated quantities of coal raised in the United Kingdom in each quarter of the year 1916, and the exports and consumption during that and the three previous years, from which we take the following figures :— Year ended Dec. 31. 1916. 1915. Tons. Tons. Northumberland .................... 11,191 ... 11,040 Durham ........................... 33,649 ... 33,738 Yorkshire ........................................... 40,070 ... 40,344 Lancashire, Cheshire and North Wales 24,754... 24,926 Derby, Nottingham and Leicester ... 32,588 ... 31,775 Stafford. Salop, Worcester and Warwick 19,846 ... 19,782 South Wales and Monmouth ......... 51,900 ... 50,453 Other English districts.............. 5,568 ... 5,440 ............................. East of Scotland .................... 12,638 ... 12,534 West of Scotland.................... 23,555 ... 23,063 Ireland................................... 87 ... 84 United Kingdom .......... 255,846 ... 253,179 _____________________________ Institution of Mechanical Engineers.—A general meeting of the institution will be held in the Institution of Civil Engineers, Great George-street, Westminster, on Eriday, April 20. The president will deliver his address. Institution of Civil' Engineers.—At an ordinary meeting of the institution in Great George-street, Westminster, on Tuesday, April 3 (commencing at 5.30 p.m.), the discussion on a paper on “ The New Electric Power House at Birchills, Walsall,” by Mr. E. M. Lacey, will be concluded. Restriction on Spelter Dealings.—The Minister of Muni- tions has issued an Order prohibiting, except under licence, or for completion of an existing contract in writing, any dealings in, or transactions or negotiations for the sale or purchase of spelter outside the United Kingdom; or the pur- chase, sale, or delivery of spelter within the United Kingdom. No licence will be required in the case of sale or delivery within the United Kingdom for necessary repairs or renewals involving the use of not more than 1 cwt. The Order also prohibits until further notice, except under licence, the use of any spelter for the purpose of any manufacture or work except for the purposes of a contract or order certified to be within Class A in the Ministry’s Order as to priority, or for necessary repairs or renewals involving the use of not more than 1 cwt. All persons are also required to furnish a monthly return of stocks of and dealings in spelter.