386 THE COLLIERY GUARDIAN. February 23, 1917. ______________________________________________________________________________________________________________________________ and Southern, 14; and two by the Board for Mining Examinations—total, 50. The Care and Treatment of Animals. The result of the census of animals employed under- ground, with particulars respecting the deaths from injury and disease and cases of injury and ill-treatment, is set out in the following table :— Particulars of Horses and Pontes Uskd Underground in all Mines under the Coal Minfs Act, 1911, during the Year 1915. Division. Number used. Number died. Number required to be destroyed. Other cases of inj ury or ill-treatment reported. From injury by accident From disease. In conse- quence of injury. In conse- quence of disease. Injury. Ill-t reat- ment. Scotland 4,626 65 112 143 65 246 5 Northern 21,551 301 187 302 278 2,262 34 York and North Midland 16,312 488 230 503 256 2,900 98 Lancashire, N. Wales & Ireland 1,700 22 29 33 10 55 9 South Wales 15,485 475 224 236 267 2,583 8 Midland and Southern 5,999 92 54 133 89 970 24 Total 65,673 1,443 1 836* ) 1,350 965+ . J 9,016 ' 178 2,279 2,315 9,194 # Of this number, 35 died from old age, or being worn out. f Of this number, 260 were destroyed in consequence of old age or blindness, or being worn out. The number of reported cases of ill-treatment was 0-27 per cent, of the total number of animals used, as com- pared with 0-29 per cent, in the previous year. The work of enforcing the Regulations relating to animals employed underground has been carried on satisfac- torily. Signalling and Visual Indicators. Dr. Wheeler, in co-operation with Prof. W. M. Thornton, of Armstrong College, Newcastle-upon-Tyne, continued the investigations in electric signalling, and extended the research so as to embrace the whole sub- ject of underground signalling in mines by means of bare wires, with a view to determining whether all such means of signalling can be rendered secure from the danger of the ignition of inflammable gaseous mixtures by the break-flash that occurs when the wires are separated after a signal has been made. The results of the enquiry were embodied in a report* dated June 1, 1916, a copy of which, by the direction of the Secretary of State, was sent to the colliery owners of the United Kingdom, with a covering circular letter from the Chief Inspector of Mines epitomising the results arrived at. Prevention of Coal Dust. The provisions under this head are, from the point of view of safety, amongst the most important and far- reaching of the Act, and much more attention is given to dealing with accumulations of coal dust. At many mines, however, much remains to be done. The Explosions in Mines Committee presented its seventh report on July 23, 1915.f The experimental work initiated by the Committee is now completed, but arrangements have been made for further work to be carried out at Eskmeals in connection with this and other mining questions under the direc- tion of the Home Office. The work, other than routine tests and analyses, that has been carried out at the experimental station during the past year can be classed under two heads, “ field ” and “ laboratory ” work. Field Work. — Experiments have been continued on the propagation of flame in firedamp-air mixtures. For this purpose, supplies of firedamp have been obtained from Cymmer Colliery, and stored in 1,000 cu. ft. gas holders. The speed of travel of flame in different mix- tures and under different conditions of ignition has been determined in the 1 ft. and 3 ft. galleries. The effect of restriction in the galleries has also been investigated. A detailed report of the work is being prepared. The conduct of the large-scale experiments is still handi- capped by lack of labour and the necessary curtailment of the expense of the experimental station owning to the war. Laboratory Work.—The chief subjects investigated have been (li the initiation and propagation of flame in firedamp-air mixtures, in co-ordination with the large- scale experiments already referred to; (2) the electrical ignition of gases; and (3) the composition of coal. The first-named research is nearing completion. The parti- cular branches of the subject now being studied are the effects of temperature and pressure on the limits of inflammability, and the relative ignition temperatures of different mixtures. The-study of the electrical ignition of gases has been mainly in connection with the problem of underground signalling. In addition, several series of experiments have been made with the object of finding out the limit- ing conditions for ignition of firedamp-air mixtures. The main object of the work on the composition of coal is to elucidate the causes of spontaneous combustion. Deter- minations of the rate of oxidation and of the tempera- tures at which self-heating takes place have been made for between 40 and 50 coals, and as a result of these and other experiments it has been concluded that one parti- cular type of compound in the coal conglomerate is mainly responsible for the self-heating of coal when exposed to air. Means have been devised for gaining a further insight into the nature of these compounds. A party of advanced students from the Department of Fuel and Technology of the Imperial College again lent their services during their summer vacation and carried out useful investigations. * Colliery Guardian, July 28, 1916, p. 157. f Colliery Guardian, December 10, 1915, p. 1181. ELECTRICITY IN MINES IN 1915. Part II. of the General Report on Mines and Quarries by the Chief Inspector of Mines states that, Mr. Nelson having joined H.M. Forces, the work of inspection of electric plant in mines and'investigating accidents at mines due to electricity, and of attending inquests and courts of enquiry following fatal accidents due to elec- tricity, has been carried out by Air. W. E. T. Hartley, junior inspector of mines, in respect of the Scotland and Northern Divisions, and Mr. W. J. Charlton, junior inspector of mines, in respect of the other four Divisions. Growth of the Use of Electricity in Mines. The Coal Mines Act requires a return to be made on January 21 of each year of the aggregate horse-power of electric motors in use above and below ground at each coal mine. A summary of the returns received on January 21, 1915, is given below :— Division. Scotland............ Northern............ York and N. Midland... Lancashire, N. Wales and Ireland ....... South Wales......... Midland and Southern Total............ Surface. Underground. Total. H.P. H.P. H.P. 33,151^... 112,223^... 145,375| 88,8741 ... 99,658| ... 188,533^ 73,855f i... 6I,446^o... 135,302 16,1801 ... 25,494| ... 41,675 109,685t95... 124,569 ... 234,254T9D 14,355 ... 45,2351 .. 59,5901 336,102| .. 468,62811... 804,731^ It will be seen from the following table that the figures for 1915 show an increase over the corresponding figures for 1914 :— Surface— Horse-power........ Per cent, increase ... Underground— Horse-power______ ... Per cent, increase ... . Total— Horse-power........ Per cent, increase ___ 1911. 1915. 291,092^... 14'58’ ... 336,1021 14*28 419,680^... 13*00 ... 468,628^ 11*66 713,782| ... 13*64 ... 804,731/o 12*74 The number of electrically - driven coal - cutting machines in use at the end of 1915 was 1,449, an increase of 34 over the number in use at the end of 1914. The horse-power of electric plant in use below ground increased by 11*66 per cent, during the year. Fatal Accidents in 1915. During the year 1915 there were in all 12 fatal acci- dents definitely due to electricity investigated by H.M. inspectors of mines, causing 12 deaths. Of the 12 elec- tric shock accidents, four took place on the surface and eight below ground. The figure for electric shock acci- dents below ground, which had decreased considerably, now shows an increase on the previous year, the number of persons killed by electric shock below ground in coal mines being in 1907, 10; 1908, 12; 1909, 13; 1910, 15; 1911, 9; 1912, 7; 1913, 13; 1914, 4; and 1915, 8. The following particulars of the fatal accidents on the surface and underground are given :— At the Birchenwood Colliery, Kidsgrove, Stoke-on- Trent, on January 8, one man was killed by electric shock while altering the position of an electric lamp, unknown to the electrician, the current being at 500 volts pressure. An examination of the lamp fitment showed that the porcelain surrounding the terminals was broken, and most of it had fallen away; the collar screw was partially unscrewed, and one of the terminals was in contact with the brass deceased held in his hand. The voltage for lighting has since been reduced to 50 volts. At the West Cannock Colliery, Hednesford, South Staffordshire, on January 10, one man was kiled by elec- tric shock. He hung his lamp on the cable in the main haulage road, and fell dead. Near the lamp a 6 in. nail was found in the cable, and a burn on the hand and arm of deceased pointed to his having been in contact with this nail. The current was three-phase, at a pres- sure of 650 volts. At the Bargoed Colliery, Bargoed, Glamorgan, on April 3, one man was killed by electric shock through contact with a stay wire attached to a wood pole carry- ing an overload transmission line between Bargoed and Elliot collieries. The stay wire was electrically charged owing to the power line falling on a cross stay, due to a broken insulator. At the Broomhill Colliery, Acklington, Northumber- land, on April 19, one man was killed by electric shock while in charge of an electrical three-phase disc coal- cutting machine in a wet place. A fault occurred on the trail cable between two phases and the earth wire, and in attempting to switch off the current he received a fatal shock, the continuity of the earthing system being inadvertently broken in the plug on the trail cable at the gate-end switch. At the Broomrigg Colliery, Bonnybridge, Stirling, on April 19, a fatal accident occurred to the man on a coal- cutting machine through the frame becoming live owing to a fault inside the motor. At the Duffryn Llantwit Colliery, Llantwit Fardre, Glamorgan, on June 8, one man received a fatal electric shock in attempting to change a blown-out fuse at an underground pump without first cutting off the current at the switch. At the Redheugh Colliery, Gateshead, Durham, on July 30, a chargeman was found dead near the switches of a 10 horse-power pump, three-phase, 300 volts, with the pump standing. Part of some rubber tape was found lying,, which had evidently come from the unarmoured leads on the live side of the switch, and a short length of tarred band had been loosely tied round the leads. At the Bardykes Colliery, Newton, Lanarkshire, on August 17, following upon a fall of roof in a roadway in which a cable was run, a repairer received a fatal shock owing to his shovel coming in contact with a haired live conductor. At the Loftus Ironstone Mine, Loftus, Yorkshire, on November 27, an assistant electrician was examining a 150 horse-power motor driven by three-phase current at 2,750 volts, and had one foot upon a loose iron plate, which tilted, and he fell forward, being then thrown back by the driving pulley. The external appearances were consistent with his having received an electric shock. At the Penallta Mine, Hengoed, Glamorgan, on December 1, a man received a fatal shock by taking hold of a range of steel tubing carrying electric lighting cables along an underground road, voltage 220. The tubing had become electrically charged owing to the insulating braid having been punctured by a joint giving way. At the Lie tty Shenkin Mine, Aberdare, Glamorgan, on December 6, whilst giving a signal on a surface incline, a man received a fatal electric shock owing to one of the signal wires being in contact with bare overhead high-tension power cables. A joint in the signal wires had given way, owing to a storm which was raging at the time, and the loose end of the signal wire was blown across the power cables. At the Leven Colliery, Leven, Fife, on December 11, an apprentice electrician opened the door of a switch panel where the pressure cf the current was 2,750 volts, and, touching live metal, was electrocuted. ___________________________ MINING EXAMINATIONS: NEW RULES. The Board for Mining Examinations have issued the following rules as to the qualifications of applicants for first and second class certificates of competency, who have served in any of his Majesty’s Forces for the purposes of the present war for a period of at least one year, and who before such service had had practical experience in mining:— In the case of a candidate who has served in any of his Majesty’s Forces for the purposes of the present war for a period of at least one year, and who before such service had had practical experience in mining, the following modifica- tions of Section 9 (2) (6) of the Coal Mines Act, 1911, and of the rules made by the Board for Mining Examinations on July 30, 1912, shall apply :— 1. The candidate shall have had such practical experi- ence in mining as is required by No. 3 of the above- mentioned rules for a period of not less than three years, or (in the case of a candidate who has received an approved diploma or taken an approved degree) of not less than two years provided :— (1) that at least two and a half years or (in the case of a candidate who has received an approved diploma or take an approved degree) one and a half years of such practical experience must have been gained either— (a) in actual practical work (i.e, exclusive of the work of mine surveying) at the working face and other parts of the underground workings of the mine ; (5) in direct supervision of such work; (c) or in both (a) and (6). (2) that the candidate shall not be entitled to receive or be registered as a holder of a certificate of com- petency until he has completed the period of practical experience in mining required by Section 9 (2) (6) of the said Act, and No. 3 of the said Rules. 2. The candidate shall be allowed, if he so desires, to take the subjects of examination as specified in paragraph 4 (a) or paragraph 4 (6) of the said Rules, in groups over a period of three years to date from his first sitting for the examination, as follows :— Group 1 __....... Subjects (i.) and (vi.) Group 2 ....... Subjects (ii.) and (iii.) Group 3 ....... Subjects (iv.) and tv.) (including in each case the oral examina- tions in those subjects), and if he qualifies in all three groups within the period of three years shall be deemed to have passed the examination : Provided— (1) that the candidate shall sit for the first group not later than five years after his release from the Colours. If a candidate is recalled to the Colours after entering for the examination, the time so spent with the Colours shall be excluded for the purpose of computing the period of three years as aforesaid. The period of three years as aforesaid shall be deemed to cover six consecutive examinations held by the Board ; (2) the candidate must to qualify in any group obtain 50 per cent, of the maximum marks, including viva voce, obtainable for each group and 40 per cent, of the maximum marks, including vwa voce, obtainable for each subject:—