122 _____________________________________________________________________________________________________________ THE COLLIERY GUARDIAN July 19, 1918. be done before .the surface lines are on the plan, and should preferably be in relation to true north, thus affording a common basis of application for all plans. On no account should the squares be put on after the surface lines. Surface surveying for the making of colliery plans will be dealt with briefly, as to go into detail would take up too much space. There is no magnetic decli- nation to worry about, whilst the accuracy and quick- ness of the work afford ample scope for the ingenuity of the surveyor. Necessity for Accuracy. The one thing that must be aimed at in connection with the surface on colliery plans is accuracy, both in surveying and in draughtsmanship. The reason for laying so much stress on this point is because, without accurate surface lines—which includes the squaring of the plan—it is impossible to fix the position of the pits on correctly; and unless the pits are fixed correctly it is impossible to co-relate surface and underground. Whilst on this subject we may consider the position of all new collieries sunk since the passing of the 1911 Act. They must have their plans on the two-chains-to-an-inch scale, which means more accurate plans, though it is very inconvenient for collieries with large leaseholds. Will the Ordnance Office issue plans on this scale, from their original surveys, as they do in the case ef the 25-in. scale, or must the colliery com- panies employ extra surveyors to do this work ? It is foolish to talk of enlarging from the 25-in. scale, the object of the larger scale being to ensure greater accuracy, not to introduce inaccuracies. Surveyors’ Examinations. The employment of surveyors to survey miles of surface and produce accurate plans brings us to the question of the standard of the surveyors’ examination. Is it possible to expect an apprentice surveyor who has served two years at a colliery, and obtained a surveyor’s certificate, to undertake work of this description ? The author has tried to show the many difficulties and inaccuracies pertaining to mine surveying, not one-tenth of which can be appreciated by a young surveyor after two years’ training; and yet he is able to get his certi- ficate and sets out to obtain a situation of responsibility, and gets it because he holds a certificate, based on an examination of no practical value. In the author’s opinion the candidate for a surveyor’s ticket should have to pass a mathematical examination. He should have a thorough knowledge of trigonometry to enable him to understand the meaning of sines, cos, tangents, etc.—not only in the first quadrant, but in the other three—then he would understand the object of having a column devoted to courses in mathematical calculations. His knowledge of mathematics should take him as far as the law of indices, to enable him to understand logarithms. It is pitiful to have to teach an apprentice how to use the log. tables, knowing that he will never master them. He may learn to look them up automatically, but there is always the danger in the manipulation of the decimal point. Then, there should be a practical test in draughtsmanship, such as the squaring of a plan. This appears simple enough, but is one of the most difficult jobs to do correctly. In the foregoing the author has tried to show the many inaccuracies in mine surveying, and perhaps a realisation of these inaccuracies will encourage employers to afford more opportunities for surveyors to improve their methods. COAL EXPORTS IN JUNE. The Board of Trade returns show that the tonnage of coal, coke and patent fuel exported during June and the first six months of 1918, as compared with the corresponding periods in 1916 and 1917,, was as follows:— Quantities. 1916. 1917. 1918. Tons. Tons. Tons. June ........... 3,503,955 ... 3,666,058 ... 2,5.c8,004 Six months ..... 20,504,687 ... 19,461,371 ... 16,553,218 The next table shows the values of these exports for the same periods .-— Values. 1916. 1917. 1918. June ............ <£4,751,977 ... £4,899,526 ... £3,623,598 Six months ...... £23,303,161 ...£25,862,547 ... £23,502,813 ___________________________ Sanitary Precautions at the Jharia Coal Fields.—Under the temporary regulations prescribed by the Government of Bihar and Orissa in August last, the chief sanitary officer of the Jharia Board of Health recently found it necessary to take certain precautions so as to check the spread of an outbreak of small-pox and cholera among the miners. Detailed instructions were issued to colliery managers regarding the treatment of the disease, and general orders were given as to registration of premises, accommodation and treatment of the sick employees at the collieries, disinfecting premises and clothes, etc., im- provement of wells and privies, and similar matters. Checking Up Slackers.—Slacker committees, made up of anthracite miners bent on singling out their fellows who are taking days off without legitimate excuse, are at work for the Lehigh Valley Coal Company. They are an answer to a patriotic appeal officials have made to the employees to eliminate unnecessary absence from work during the present grave labour shortage to the anthra- cite fields. The president of the company says that the results are already better than they had dreamed. They are having good speakers talk to the men, pointing out existing conditions and appealing to them, from patriotic motives, to co-operate to their fullest extent that a maxi- mum coal output may be attained. At every colliery giant thermometers have been erected which show the ton- nage produced by that colliery each day as compared with its best record, and alongside are names of absentees, with an estimate of what the tonnage would have been if all had been at work. The effect has been electrical. Practi- cally every man has been put on his mettle, and there is a general demand by the men to be put on these “ slacker ” committees. THE DOMBROVA COAL FIELDS. By Arthur E. Gurney. Situated in the extreme south-western corner of the Kingdom of Poland—commonly called “ Russian Poland ”—the Dombrova coal fields form the eastern continuation and termination of the Silesian deposits, whilst on the south they merge into the Galician coal fields. Their extent has been variously estimated between 170 and 195 square miles (440-500 square kilo- metres), but they have not yet been sufficiently ex- plored to allow of Jheir eastern limits being definitely ascertained. There are said to be reliable indications that the area is considerably greater. From the geological point of view the deposits of the Dombrova coal fields resemble those of Upper Silesia, lying comparatively near the surface and having only a moderate dip. The seams are, however, even thicker, attaining in some cases—in the neigh- bourhood of the settlement of Dombrova—a thickness of more than 60 ft. Seams of 40 ft. are of frequent occurrence, and those measuring 16 ft. to 20 ft. are quite common. The seams alternate with layers of clayey schist and sandstone to an aggregate depth of 5,580 ft. The deposits principally being worked are those of the Reden group, which derive their name from the Director of Mining under whom the industry was started in this part of Poland. They are situated in the southern portion of the Dombrova coal fields, around Dombrova Gornicza, and correspond to the so- called Sattelfloetz-Schichten of Upper Silesia. The seams are fifteen in number, with a combined thick- ness of 108 ft. Although the quality of the coal ob- tained is in general excellent, no coking coal and anthracite have as yet been discovered. Most of the Polish and German geologists (Grzybow- ski, Kontkiewicz, Freeh and others) who have studied the subject estimate the resources of the Dombrova coal fields to a depth of some 3,280 ft (1,000 metres) at 5,000 million tons, and one of the former (Wojcik) at 5,562 millions. But these figures, like those relating to extent, are only a rough estimate, and much fuller investigations will be required before definite conclusions can be formed. Coal mining was begun in the kingdom in 1796, to supply the needs of the zinc furnaces, and, notwith- standing many adverse circumstances, the industry has developed very steadily, as the subjoined table shows : — Output of the Dombrova Coal Fields. Year. Output in metric tons. 1816__________________ 3,500 1850 _____________ ... 135,770 1870 __________________ 330,785 1890 __________________ 2,584,612 1900 ________ _______ 4,014,079 1910 __________________ 5,468,763 1911 __________________ 5,769,928 1912__________________6,315,430 1913 ... _____________ 6,833,587 The only year which showed any considerable de- crease in the output was 1905, when, in consequence of the economic depression brought about by the Russo-Japanese War, and the state of social unrest prevailing in the whole of the Russian Empire, the production fell to 3,507,936 metric tons, or approxi- mately the quantity produced in 1895. The output __________________________ Class of labour. Year. Increase ( + ) or decrease (—). Year. i Increase () or decrease (—). 1908. 1909. 5,128 10,386 6,165 1,011 1910. 5,391 10,399 6/25 1,100 • 191L . 1912. Hewers Underground assistants Surface assistants Women Total Output in metric tons 5,157 10,423 5,725 966 Per cent. + 3’34 - 0’23 + 13’60 + 1217 i 5,068 9,707 6,496 1,000 5,121 9,964 6,736 1,076 P< r cent. - 501 - 419 + 1’64 - 2T8 22,271 5,520,971 22,690 5,584,183 23,516 5,468,763 + 5’29 - 0’95 22,271 5,769,928 22,897 6,315,430 - 2’70 + 15’48 quickly recovered, however, rising in the very next year (1906) to 4,550,946 metric tons, and since then the upward tendency consistently prevailed till war broke out. In 1901 about 84 per cent, of the output of the Dombrova coal fields was produced by the mines owned by nine affluent joint stock companies, while twenty- one minor concerns supplied the remainder. By 1910 the contribution of the former had risen to 95 per cent., and the number of the latter had dropped to fourteen. The large companies in question were the Sosnowice, Saturn, Czeladz, Grodziec, Warsaw, Franco-Italian, Franco-Russian, Flora, and Count Renard companies, which in 1910 owned sixteen ex- tensive mines. The table given below shows in detail the output of the various concerns in the years 1901 and 1910, and the proportion of the separate contributions to the total production of the Dombrova area in those years:— 1901. 1910. Name of Output Per cent. r ■ Output in Per cent. company. in metric of metric of tons total. tons. total. Sosnowice 940,588 . ... 22’7 ... 1,328,521 ... 24’3 Saturn 430,573 ... 10’4 ... 666,079 ... 12’2 Warsaw 545,365 ... 13’2 ... 628,130 ... 11’5 Count Renard... 585,983 ... 14’1 ... 564,994 ... 10 3 Franco-Italian.. 446,615 ... 10’8 ... 540,437 ... 9’9 Czeladz 267,100 ... 6’4 .. . 493,338 ... 9’0 Grodziec 2,665 ... 0’2 .. . 480,766 ... 8’8 Flora 195,724' ... 4’7 ... . 272,459 ... 4’9 Franco - Russia n 81,420 ... 2’0 ... 213,138 ... 4’0 Other concerns 643,407 . ... 15’5 ... 280,898 ... 5’1 Total 4,140,439 . .. 100’0 ... 5,468,763 ... 100’0 Compared with that of the British mines, the out- put of the Dombrova coal fields will appear relatively insignificant. The importance of those coal fields will, however, be better appreciated when the extent of their resources is borne in mind and it is remembered that, as the figures already quoted prove, the output increased in the course of the thirteen years imme- diately preceding the war by 70-24 per cent., whereas the production of the British mines increased during the same period only about 16 per cent. No other European coal fields, with the solitary exception of the Russian mines, can show a similarly rapid de- velopment, and in the case of the Polish areas this will, shortly after the war, be enormously accelerated by the greatly improved conditions and highly in- tensified industrial activities which may be expected to ensue. The average depth of the shafts existing in 1909 was 705 ft. Only thirteen had been sunk to a greater depth than 656 ft. (200 metres), and of those only six exceeded 984 ft. (300 metres). The deepest were the Kazimierz mines, which had a depth of 1,542 ft. As regards methods of working, the mines of the Dombrova coal area were until comparatively recently in a very backward state. Great improvements have, however, been introduced during the last few decades, and the mines of the Kingdom are now, in this respect, in many cases on a level with those of Western European countries. Up to about ten years ago the system almost univer- sally employed in working the deposits was the Silesian method of working thick seams, consisting in driving outwards galleries 13 ft. in width and of the same height, or, in the case of seams of not more than 20 ft., carried through their entire thickness. Since then this method has, however, been generally dis- carded in favour of the pillar system, which before had been adopted in only three mines. The gradual extension of the application of mechani- cal energy is shown below, as well as the average amount of horse-power required for every ton of coal raised. Horse-power of Steam Engines in Use. Year. Total horse- Per 1,000 tons power. of output. 1885 8,547 4’77 1891 10,981 4'21 1895 17,967 4’87 1899 20,262 5’08 1902 27,046 6’39 1905 34,628 9’87 1908 39,007 7’06 1910 42,317 7-70 Electric Motors. Horse-power. Year. No. of motors in use. Total. Per 1,000 tons. 1908 174 ...... 13,735 2’5 1909 206 17,995 3’2 1910 247 21,944 4’0 In the following years not only was the application of mechanical energy rapidly becoming general, but electric motors were increasingly supplanting steam engines. In consequence of these improvements the great rise in the output of the Dombrova coal fields was not accompanied by a proportionate increase in the number of hands employed. On the contrary, they actually diminished, the decrease being most marked in the better-paid classes of labour. In this connec- tion the following table will be of interest. It shows the proportions of output to the numbers of hands* employed during the five years immediately preceding the war for which reliable figures are available : — As the above table proves, the average output per hewer rose from 1,070-6 tons in 1908 to 1,138-5 in 1911, and 1,233-2 tons in 1912. The effect of the adoption of improved methods of working on the cost of production was equally marked, as the sum paid in wages for every 100 tons of coal produced dropped from £16 17s. 8d. in 1908 to £15 19s. lid. in 1911, and £15 9s. 3d. in 1912. In the latter year the total amount paid in wages by the mines of the Dombrova area was equivalent to £976,496, and the average annual earnings of the hands employed were: Hewers, £68; underground assistants, £36 9s.; surface assistants, £36 2s.; women, £17 15s. In how far the adoption of the pillar system con- tributed towards decreasing the cost of production may to some extent be gauged by the following figures. They represent the cost of extraction per ton, in 1902, in some of the principal pits, the first three mentioned being those worked on the new system : — Cost per Name of mine. metric ton. s. d. Paris 2 8^ Reden 3 71 Koszelew 3 11| Kazimierz 4 6 Milowice 5 0 Niwka... 5 51 Count Renard 5 8> Mortimer 5 10T% By far the largest proportion of the capital invested in the Dombrova coal fields was of foreign origin, the majority of the shares being in the hands .of German, French, American and Russian capitalists. The order in which they are mentioned indicates the relative importance of the investments of each nationality. The average annual dividend paid by the eight largest concerns during the years 1908 to 1912 inclusive was 11-4 per cent., and in the latter