654 THE COLLIERY GUARDIAN October 6, 1916. Experiment 3. Using i3,. in. length of 0*0015 in. diameter platinum wire only, in series with 2*0 volt 0*85 ampere lamp. Amperes. 0*50 ... Lamp glowing (orange.) With 1-87 m. of manganin wire in parallel with platinum wire, and both in series with filament lamp. Amperes. 0*85 ... Lamp brilliant, and platinum between white and orange. With platinum cut out, lamp not glowing. Amperes. 0*40 ... Current through res. and lamp only. (Res. of 4*0 m. of manganin wire used 19*715 ohms.) The lamp filament was glowing orange with 1*37 m. of manganin wire in series with lamp. With 0-9 m. of manganin wire in circuit, it was considered that the lamp was giving just sufficient light to see by. Amperes. Volts. 0*6 ... 0*94 (across the lamp.) Two 2-volt cells were used, which (in series) gave 4*40 volts. (Capacity of cells same as previous experiments.) Note.—The full voltage of the cells was not across the lamp, platinum and manganin wires, but the current was passed through a resistance to give the desired quantity. Experiment 4. Using J in. and in. length of 0*0015 in. diameter platinum wire in parallel, and both wires in series with a 2-volt 0*85 ampere lamp. Appearance of platinum wires :— | in. wire glowing bright cherry red. in. wire not glowing, but feeling warm to the touch. Volts across whole arrangement, 2-88. ,, both platinum wires in parallel, 0*68. ,, lamps, 2*2, and ampere 0*92. With | in. wire cut out, volts above 3*0 ai d ampere 0*54. in. wire, glowing bright orange. Lamp filament nearly incandescent, volts (across lamp) 0*42, and ampere 0*54. Experiment 5. Using in. length of 0*0015 in. diameter wire in parallel with manganin wire (on a potentiometer). Length of manganin wire, 1*73 m. Two volt 0*85 ampere lamp in circuit (series). Volts across lamp (both wires in), 1*83 volts 0*85 ampere. ,, platinum wire cut out, 0*62 volt 0*85 ampere. With res. wire only in lamp, filament nearly orange. ,, ,, and platinum wire in lamp, brilliant, and platinum wire bright cherry red. Experiments with Tungsten Wire in Air and in Mixtures of Coal Gas and Air. Experiment 1. Using a 2 volt 0*85 ampere lamp, and an adjustable resist- ance, current being adjusted to 0*9 ampere (at 2*20 volts;, and then switched off, a length of wire 14 mm. in length and 0*065 mm. in diameter being then put in circuit. When current is switched on again, the amperes were noticed to be 1*03. Wire fused in 30 seconds. Amperes dropped rapidly from 1*03 to about 0*6 before wire fused. This test was made in air. Experiment 2. Arrangement and connections as preceding experiment. Mixture of 2*5 per cent, of coal gas and air. Volts and amperes same as preceding experiment. Using 14 mm. of 0-065 mm. tungsten wire, the current was switched on, whereupon in 65 seconds amperes dropped to 0*42, and in three minutes to 0*35; in four minutes to between 0*35 and 0*34; in five minutes to 0*33; in seven minutes to 0*32; in 8| minutes to 0*31; in llj minutes to 0*30; and in 15 minutes to 0*30. Current then switched off. This experi- ment lasted 15 minutes in the mixture; the wire was not fused. Using same wire, but this time in air only, there was a sharp rise from 0-30 ampere to 0*60 on switching on the current, followed by a drop to 0*28, 0*27, 0*21, 0*20 during five minutes, then, in the next two minutes, to 0*16, and gradually to 0*08, 0*07, the amperes remaining constant during the next five minutes. Wire not fused. The experi- ment in air lasted 30 minutes. Experiment 3. Arrangements as in previous experiments, but with a mixture of 6*5 per cent, of coal gas and air. On current being switched on, the amperes 1*02 dropped slowly to 1*01, 0*99, 0*95, then rapidly to about 0*6. Wire fused. A bright reddish-yellow flash noticed in the neighbourhood of the wire. Time from switching on until fusion, about 25 seconds. Experiment carried out in darkness, excepting a shaded reflected light on the ammeter. A sample of this gas mixture tested with a lighted taper showed a marked elongation of the flame. State Mining in New South Wales.—At Lithgow recently Mr. Estell, State Minister for Mines, turned the first sod for the shaft of the flrst State coal mine, which is to be started on an area of 40,000 acres of Crown land reserved for this purpose. Mr. Estell said that the boring showed a 6 ft. seam of good coal, and that it was estimated that the area contained 210,000,000 tons of coal. It was proposed also to establish a State mine in the north of the State and another in the south to meet the requirements of the State Railways, which at present consumes 1,250,000 tons a year. There was no reason, he continued, why private collieries should not work harmoniously alongside the State mines. French Safety Explosives Recommendations.—In conse- quence of miss-fires and blown-out shots with Carbite No. 2 (an explosive of the ammonium nitrate group), the French Explosives Committee recommend that, when this explosive is used, care should be taken to drill the shot holes so that the cartridges can be inserted easily, but without too much play; that the holes should be freed from coal dust; that the cartridge wrappings should be carefully removed without tear- ing the inner envelopes; that the detonator should always be fixed in the last cartridge inserted in the hole; and that all the cartridges should be inserted together, with their ends in close contact, and carefully stemmed to prevent distortion. The cartridges should be stored in a dry place, and not kept more than a month before being used, and should be tested on arrival, another test being applied to such as have been stored, in order to detect any deterioration. In gassy dis- tricts, ammonium nitrate explosives alone should be used for shooting down the coal. COAL MINING IN INDIA IN 1915. The annual report of Mr. G. F. Adams, Chief Inspector of Mines in India, for 1915, has been issued. Some extracts are given below. Persons Employed. During 1915 the average number of persons working in and about the mines regulated by the Indian Mines Act was 180,088, of whom 118,017 worked underground and 62,071 on the surface; 112,787 were adult males, 62,096 were adult females, and 5,205 were children under 12 years of age. This is a decrease of 5,123 ■workers, or 2*77 per cent. Those employed in coal mines numbered 145,537, which is an increase of 7,686 over those employed in 1914. In the Raniganj coal field (Burdwan district) the supply of labour was reported to be unusually plentiful, owing chiefly to a bad harvest in the previous year. In the neighbouring district of Ban- kura the scarcity amounted to a famine, and labour flocked to the coal mines in large numbers. There are, however, in this coal field outlying mines where more Table showing Number of Mines Regulated by the Indian Mines Act, 1901, Number of Workers, and Output of Minerals during the Year 1915. Province. District and mineral field. No. of mines under the scope of the Act. No. of mines worked by mecha- nical power. Total output 1 (tons). A verage number of persons employed daily in and about the mines. Below ground. Above ground. Total. Assam * Lakhimpur 8 5 308,071 1,883 881 2,767 Naga Hills - 1 — 2,872 42 70 112 Total 9 5 310,943 1,925 954 2,879 Kalat 3 — 3,047 27 10 37 Baluchistan Loralai Quetta-Pishin 1 9 — 287 4,491 15 69 8 41 23 110 Sibi-Khost 8 2 35,782 481 312 793 Total 21 2 43,607 592 371 963 Bankura, Raniganj 2 — 5,197 45 26 71 Bengal Birbhum, ,, 1 — 1,944 16 12 28 Burdwan, ,, 173 146 4,968,319 28,106 13,888 41,994 Total 176 146 4,975,460 28,167 13,926 42,093 1 r 0 Bokaro-Ramgarh 5 — 4,333 81 31 112 Hazaribagh j Giridih 8 5 872,647 6,3>3 2,682 9,005 (Jharia 7 3 63,579 1,636 375 2,011 Manbhum {Lniganj'.'.'.'.'.'.'.'.:... 257 153 9,077,221 49,075 27,271 76,346 Bihar and Orissa ...*( 71 7 507,077 3,471 1,535 | 5,006 Palamau, Daltonganj 1 1 85,785 547 308 855 Sambalpur, Hingir-Rampur ... 1 1 58,825 431 217 648 Sonthal ( Jainty 2 1 39,830 204 902 1,106 1 i P. rganas (. Raniganj 2 — 2,059 23 8 31 Total 354 171 10,711,356 61,791 33,329 95,120 Burma Bhamo 1 — 25 8 8 16 Chanda, Ballarpur 3 2 94,880 551 282 833 Central Provinces ... Chhmdwara, Pench Valley 8 7 103,152 818 300 1,118 Narsinghpur, Mohpani 1 1 55,086 804 416 1,220 Yeotmal 1 — — 5 8 13 Total 13 10 253,118 2,178 1,006 3,184 North-West Frontier Hazara 1 — 60 9 — 9 Jhelum 5 — 51,613 670 352 1,022 Panjab < Mianwali 1 — 2,029 56 13 69 Shahpur : 2 — 4,269 117 65 182 Total 8 — 57,911 843 430 1,273 Grand total for 1915 583 334 16,352,480 95,513 50,024 145,537 ,, ,, for 1914 610 326 15,727,631 88,199 49,652 137,851 labour would have been welcomed. In the Jharia coal field also the year was considered to be a good one generally. The labour question continues to be a very difficult one in the Assam (Lakhimpur) coal mines. In addition to Indian coolies, Nepalese, Mekranis, and Chinese have all been tried. Of the former 832, and of the two latter 130 and 68, respectively, were recruited during the year. The Chinese have proved unsatisfactory, and it is not proposed to recruit any more of them. Output of Coal. The total output of coal was 16,252,480 tons, an increase of 624,849 tons, or 3*97 over the output of 1914. This is the first year in which the 16th million has been reached. An analysis of the figures shows that, as far as the coal fields of Bengal and of Bihar and Orissa are concerned, the year was remarkably one of large increases and decreases. The outputs of the larger firms and of those working the best seams increased. Those of the smaller owners and of those working the inferior coals decreased. In Bengal (Raniganj coal field)', where the total increase is almost entirely accounted for, the increases were over 800,000 tons, and the decreases over 300,000 tons, resulting in a net increase of over half a million tons. In Jharia, the figures are still more emphatic. The total output of the field was stationary, but the increases and decreases, which practically balanced one another, were each over a million tons. The year 1915, therefore, was distinctly the period of the best seams and of the large owner, and the increase of output kept pace with the demand. Reduction in finance facilities, the closing down of much internal industry, and the restriction of commerce, forced a good deal of extra coal on the market early in the year, and brought down prices. This reacted on the industry generally throughout the year, and affected specially the small owner and those working inferior coals. More and more coal had to go by rail as the year went on, until, at its close, practically all that was used in India, exclud- ing small quantities destined for a few towns in the far southern corners, was so carried. Of the total output, 15,686,816 tons, or 95*93 per cent., were raised in Bengal and in Bihar and Orissa, the per- centage of the previous five years being 95*54. In the other provinces, there was again a decrease in Baluchi- stan amounting to 9*59 per cent., and there were increases in the Central Provinces of 3*42 per cent., in the Panjab of 6*64 per cent., in Assam of 2*06 per cent., and in the North-West Frontier Province (output negligible) of 36*17 per cent. The output per person employed during the year was (a) below ground 171 tons, and (b) above and below ground 112 tons. The figures for the five yeans preceding were (a) 177 tons and (5) 114 tons. Taking each group of coal fields separately, these figures were as follows :—Bengal and Bihar, (a) 174 and 181 tons, (b) 114 and 115 tons; the Central Provinces, (a) 116 and 124, (b) 79 and 87; Assam, (o) 162 and 201, (b) 108 and 129; Baluchistan, (a) 74 and 73, (b) 45 and 48; and the Panjab and North-West, (a) 68 and 55 tons, (b) 45 and 35 tons. The table appended shows the number of coal mines regulated by the Indian Mines Act, 1901, the number of workers, and the output of mineral during 1915 :— Accidents. During the year 1915, at mines regulated by the Indian Mines Act, 1901, there were 163 fatal accidents, being an increase of 11 on the number in 1914, and an increase of 28 on the average number in the previous five years. The increase is chiefly made up of accidents from falls of roof and accidents on the surface, of the latter of which there were 37, as compared with 17 in 1914. There were increases in all the four sub-heads into which surface accidents are classified. The prin- cipal fields in which accidents occur are : (1) the Bengal and Bihar and Orissa coal fields, (2) the Assam (Lakhim- pur) coal field, (3) the Baluchistan coal field, (4) the mica fields, (5) the manganese fields, and (6), during recent years, the wolfram field. In looking over the fatal accidents both for 1915 and for the previous five years, it is found that there has been a gradual increase of accidents in No. 1 field. In No. 2 field there was a decline during the first half of the period, and a steady increase during the second half. The exact converse has been the case in No. 3 field, while the numbers have remained more or less stationary in Nos. 4 and 5 fields. The rate for wolfram (No. 6) is high, and varies considerably. The Indian Mines Act was passed in 1901, but some two or three years elapsed before the reporting of acci- dents and the returns of labour approached to a fair degree of accuracy, and it is considered that the end of the year 1915 may well be taken as the end of the first decade, as far as these matters are concerned. The chart of the death rates per 1,000 persons employed for the 10 years ending with 1915 shows that coal mining in Assam and Baluchistan is a very much more hazardous occupation than in Bengal and in Bihar and Orissa. This is chiefly due to the naturally dangerous conditions of the first mentioned mines. In connection with the coal fields of Bengal and of Bihar and Orissa, it should be noted that during the 10 years under review, the character of the mines has undergone a great change. There are many more deep shafts, mines have been extended greatly in area underground, and there is far more machinery in use.