From the Transactions of the Institute of Mining Engineers, Vol. XLV, 1912-13, pp.88-106. Reproduced by kind permission of the institute
The Jherria coal-field lies along the Damucht Valley, about 170 miles from Calcutta, and forms part of the Damuda Series of measures. This series belongs geologically to what is known as the "Lower Gondwana System," and is itself divided into the following stages:- (1) The Barakar Series of Coal-Measures, (2) The Ironstone Shales, and (3) The Raneegunge Series of Coal-Measures.
Sir Thomas H. Holland states the thickness of the Barakar Series of Coal-Measures to be 2,000 feet, the Ironstone Shales, 1,400 feet, and the Raneegunge Series of Coal-Measures, 5,000 feet.( Sketch of the Mineral Resources of India, by T. H. Holland, 1908, page 13. “ Report on a Survey of the Jherria Coal-field," by Thomas Henry Ward, Records of the Geological Sursey of India, 1892, vol. xxv., page 110.) The Jherria coal-field belongs principally to the first and lowest of these three stages.
Development of the Coal-field.-Owing to the difficulty in transit, as compared with the Raneegunge coal-field, which lies about 50 miles nearer Calcutta, and in which coal-mining has been profitably carried on since about the year 1835, no steps were taken to work the Jherria coal-field until about the year 1891, when, owing to the increasing demand for coal, its development received attention. In the year 1890, the East Indian Railway Company arranged with Mr. T. H. Ward for a survey of the coal-field (“ Report on a Survey of the Jherria Coal-field," by Thomas Henry Ward, Records of the Geological Sursey of India, 1892, vol. xxv., page 110.), and subsequently published a map, copies of which were supplied to anyone interested; and it was largely due to the enterprise of this company that a great proportion of the coal-field was quickly taken up. The extension of the railway from Barakar, some 30 miles distant, and at that time the nearest point on the East Indian Railway, was at once undertaken and carried through by the company.
For a number of years it was only with difficulty that the Jherria coal could find a market, and compete successfully with the better-known coals from the Raneegunge coal-field. This was due partly to the lower and inferior seams, with their more clearly-defined outcrops, having received the first attention, but still more to the higher railway-freight charged to all points, as compared with the Raneegunge coal-field. The first difficulty was quickly overcome by the development of the field and the determination of the quality of the various seams; while, with regard to the second, the East Indian Railway Company was always ready, as far as possible, to meet the coal-owners and adjust freights. Thus, in the year 1894, representation was made to the company drawing attention to the impracticability of further development under the then existing conditions, and in the year 1902 a new coal-tariff was introduced. The trade has also been greatly assisted by the laying-down of the Grand Chord line, and by the enterprise of the Bengal-Nagpur Railway Company in putting in sidings where required, an enterprise which will be still further rewarded in the future as the development of the field trends further southwards and westwards.
The exposed area amounts to nearly 92 square miles, or, say, 58,843 acres (178,000 biggahs, this being the usual Indian measure of area). A Bengal. biggah is equal to 14,400 square feet, and, in calculating English equivalent,, 310 biggahs are taken as equivalent to 1 acre.
The greater part of the field has been taken up by various companies and Europ*n and native private owners, although up to the present the area worked may be said to be only along, the outcrops, no coal having been worked at a greater depth than 500 feet, while the great bulk of the workings are within 250 feet of the surface. There are over two hundred collieries, but some of these, which started work in the prosperous years 1907 and 1908, are now closed down. Out of the total area, about 23,100 acres (70,000 biggahs) have been taken up and are being worked by fifty-three of the more important companies, which are under European management; and these have raised about 80 per cent. of the coal worked up to December, 1910, or about ;15 million -rut of a total of 43 1/3 million tons.
In dealing with the various coal-seams, their available areas, and the approximate available tonnage contained, the numbering as given by Mr. R. D. Oldham has been followed, and the seams are therefore numbered upwards from 1 to 18, commencing from the northern and eastern outcrop of the field. No account is taken of the area (26 2/3 square miles) on the west, in the neighbourhood of Alhoda, where the coal, although dealt with by the Jherria coal-field railway system, belongs to the Raneegunge and not to the Barakar Series of Coal-Measures: nor has any account been taken of the concealed area lying below the Ironstone Shales and Raneegunge Series of CoalMeasures (about 53 square miles). The stated quantities, areas, and thicknesses of the seams are in all cases approximate.
Fig. 1 (Plate IV.) embodies sections indicating the relative positions of the seams at two points, namely, A and B (Figs. 2, 3, and 4, Plate IV.). The distances between the seams and the thickness of each seam are the average for the district in which the section is taken, and are not necessarily correct for the points indicated.
Throughout the whole of the coal-fields of Bengal, and particularly in the Jherria district, a very large amount of the coal has been destroyed by burning, and the coal thus burnt has received the name of "jharna." Apparently at some period subsequent to the deposition of the Coal-Measures, a vast upheaval took place, during which innumerable streams of molten matter- trap-dykes, chiefly dolorite and mica-peridotite- were forced up through the coal-fields and surrounding measures. Where these streams have penetrated the Coal Measures, they, in some cases, appear to have passed through a seam in the form of vertical sheets or walls varying from 3 or 4 inches to 30 or 40 feet in thickness, without having appreciably affected the coal to any great distance on either side; while, in other cases, the molten strata appear to have found some line of weakness above, below, or, in some cases, in the seam itself, and have spread out in sheets over large areas. In these latter cases the coal is almost invariably burnt for a greater or less distance away from the sheet, a 30-foot seam being often found with perhaps 4 or 5 feet unburnt in the centre, or at the top, or at the bottom. This burning of the seams varies all over the coalfield, those seams which are completely burnt at one point being untouched at another only a mile distant; while possibly another seam has been destroyed at this point which is untouched at the first. It is, therefore, impossible to estimate the conditions at one point on the basis of those observed at another, and the results obtained from boring cannot be relied on, since in the area to be proved any particular boring may have passed through the only burnt or unburnt patch of coal as the case may be. The presence of "jhama" also causes the estimation of the quantity of coal in any area or seam to be problematical. Unfortunately, so far as can be judged, the better classes of coal appear to have suffered quite as much as, if not more than, the seams containing coal of inferior quality.
Figs. 2, 3, and 4 (Plate IV .) illustrate the lines of outcrop of three of the principal seams, Nos. 17, 15, and 10, together with the main features of the coal-field, which will have a bearing on its future development, such as railways, roads, rivers, etc. The outlines are reduced from Mr. G. A. Stonier's " Map of the Jherria Coal-field," published as a supplement to the Colliery Guardian for September pith, 1904.( 1904, vol. lxxxviii). The areas over which coal has been partly or wholly worked, together with the lines at which the probable depth of the coal will amount to 500 feet and 1,000 feet respectively, are also shown. Although the proportion of coal worked up to December, 1910, to that probably available at a depth of 500 feet and under, is comparatively small, it will be seen that in certain districts, notably that lying to the dip and north of Bliaga railway-station, the necessity for deeper shafts will soon have to be considered. The outcrops of the various seams, it will be noted, lie in a curve, the chord of which rues from east to west; while the clip, which in the centre of the field is fairly constant (I in 10 to 1 in 12), increases very much towards the eastern and western extremities, being as great as 1 in 1 to 1 in 1 1/2 in the east, and 1 in 3 to 1 in 4 in the west.
Appendix I. deals with the quantity of coal raised in the Jherria district, Bengal, and the Indian Empire, for the years 1894 to 1910; while Appendix II gives the approximate total quantity of coal raised, etc., in each of the seams during that period, the lower seams, Nos. 1 to 8, being grouped together.
Appendix III gives the following details for each seam, the lower seams, Nos. 1 to 8, being again grouped together:-
(1) Seam number.
(2) Total exposed area.
(3) Percentage of area unworkable, owing to the coal having been burnt, or to dykes, faults, etc.
(4) Average thickness.
(5) Total tons in exposed area, after deducting the percentage that is unworkable.
(6) Total tons at depths of less than 500 feet.
(7) Total tons at depths of over 500 but under 1,000 feet. (8) Total tons worked to December 31st, 1910.
(9) Percentage of total tons worked to December 31st, 1910, to total tons in the exposed area.
(10) Percentage of total tons worked to December 31st, 1910, to total tons at depths of less than 500 feet.
(11) Quality of coal.
(12) General.
Appendix IV embodies analyses of coal from seams Nos. 18 to 10, which, however, cannot be considered representative, since an analysis of the coal from any particular seam varies very considerably in different parts of the coal-field. Each analysis, however, may be taken as representing broadly the character of the seam from which it is taken. The coal as a whole is high in ash, this, with the exception of the Assam seams, being the case with all Indian coals.
In considering future development, the following heads have been taken:-J) Power, (2) deep shafts, (3) system of working, (4) haulage, (5) pumping, (G) ventilation, (7) cost of working, (8) labour, and (9) general.
(1) Power.-
The more economical production and transmission of the power which will be required for the development of deeper workings is one of the main points to be recognized. At present the greater part of the coal is obtained from inclines along the outcrops of the various seams-worked by manual or mechanical haulage-and from shallow shafts, the bulk of the working, of which lie to the dip. Each mechanical incline and shaft is fitted with its own series of boilers, engines, and pumps. These remarks refer generally to the whole coal-field, since in some cases inclines and shafts have been or are being laid out and developed with full regard to the advantages of centralizing the plant and capital outlay required to give the best results.
For the development of the deeper workings, with the necessarily greater lengths of underground haulage and pump-lines, electric power at once comes into consideration, with the alternatives of a power-supply company or a private installation. Up to the year 1911, five companies had installed their own generating plants, with a total capacity of about 1,500 kilowatts. All these plants, with one exception, are driven by high-speed engines producing three-phase alternating current, and for the most part have all proved entirely satisfactory. A general power scheme was brought. forward in the year 1908, and the authority to form a company obtained, but for various reasons this was allowed to drop; and, although subsequent attempts have been made to revive it, or to introduce an alternative arrangement, nothing definite has yet been done.
Looking to the future, it is evident that more and more electric or other power will be required, and although in individual cases a private installation may possibly prove more economical than current obtained from a general power company, this will undoubtedly prove the exception. One or more power companies will, therefore, have to be formed to deal with the requirements of the coal-field, the shape and formation of which lends itself to the development of central stations.
So far as private installations are concerned, there seems to be no doubt as to the suitability of high-speed compound sets in all cases where the largest generator installed has a capacity of not more than 700 to 1,000 kilowatts. There is no reason why native enginemen should not, with proper supervision, be as capable of looking after a high-speed as of a low-speed set. For a general power installation various types of prime movers may be considered, among which are (a) gas-engines, (b) steam turbines, and (c) high- or low-speed reciprocating engines.
(a) Gas-engines.-The application of these would necessitate the use of suction gas-engines, or of running the supply company in connexion with a bye-product or other form of coking plant. Suction gas-engines might possibly be used with success, although it is believed that large suction gas-plants have not proved so uniformly successful in India as to warrant their
adoption without very 'careful trial; and more particularly as the question of fuel-consumption is not of so serious an import as it is in the case of places where a high railway freight makes such consumption one of the heaviest items to be reckoned with. The running of a power-supply installation in direct connexion with a bye-product coking plant would ensure a double advantage, as it would give a constant supply of gas to the power plant and a regular outlet for the surplus gas from the cokeovens. This scheme, however, seems hardly feasible, as the Tata Iron &. Steel Company (who went very carefully into the question of installing the coking plant which was required for their steel-works, on the coal-field) decided to give up the idea, and have now installed the plant required at their works at Kalimati. The chief objections to such a plant being installed in the Jherria district were the difficulty in utilizing the surplus gas, and the uncertainty of being able to obtain a sufficient water-supply throughout the year without the expense of constructing the enormous reservoirs which would otherwise be required to keep the plant working during the dry season.
(b) Steam-turbines.-There appears to be no reason why this system should not be adopted, either alone or in connexion with high- or low-speed reciprocating sets.
(c) High- or Low-speed Reciprocating Engines.-It would seem the most obvious course to adopt this system, but the question of the respective advantages of low- and high-speed types need not be gone into here. High-speed sets, with or without the addition of low-pressure turbines, present the most probable solution.
Alternating three-phase current has almost universally been found the most suitable for heavy power requirements, and would doubtless be adopted. The question of the voltage advisable at the generating-station, and for transmission purposes, will not be dealt with; but, in view of the comparatively small area, this should present no difficulties. For underground use, medium pressures would be generally adopted, on account of the restrictions under the Indian Electricity Act.
(2) Deep Shafts.-The deepest shafts at present sunk are just over 500 feet. In the course of the next few years this depth will certainly be greatly exceeded, and the time is not far distant when shafts of 1,000 feet and upwards will have to be sunk. It is well known that it is more expensive and difficult to sink a shaft in the Jherria than in the Raneegunge coal-field, on account of the much larger quantity of water and the more difficult strata met with. In the past a great many of the difficulties have been created by an inadequate supply of power for winding and pumping, thus causing constant delay and expense. Where ample power for all probable requirements has been provided, sinking can be carried on economically and efficiently; and even for a shaft 1,000 feet deep, there is no reason why the sinking should not be carried out at an average cost, for sinking only, of between £2 and £2 13s. 4d. (30 to 40 rupees) per foot.
For the sinking of shafts of any considerable size and depth, the provision of permanent and powerful headgear and winding engines is necessary. To commence sinking with temporary plant, in order to make an early start while the permanent winding-gear is being ordered and erected, will almost invariably be found in the long run to be a much slower and more expensive method than to put down the permanent winding engines and headgear at the commencement, and to install proper pumping arrangements for dealing with whatever water may be found., Under steady supervision, certain classes of native labour can give excellent results in sinking; and, if power-drills are used with a small electric or steam-driven compressor, a good return will be obtained on the money spent, especially where there are any beds of hard strata to be passed through. On the completion of the sinking, the compressor and drills will be found of great use fir main-gallery driving, or where jhama is found in the workings.
The proper and efficient lighting of the shaft-bottom while sinking is going on is also an expenditure which is well paid for by results.
At present there have been no indications of gas in any of the shaft-sinkings ; but in sinking some of the newer shafts in the Raneegunge district, safety-lamps have been made compulsory. It is probable that gas will also be found in the Jherria coal-field as the sinkings increase in depth.
(3) System of Working.-
As greater depths and more extended workings are attained, a considerable alteration will have to be made in the systems of working, although this matter has already received much attention, and any inspection of the present workings at the larger collieries will shoe- a very- great change for the better, as compared with ten or twelve years ago.
Three of the chief faults in the earlier laying-out and working of the collieries are the following:-
(a) The driving-in of far too many inclines from the surface along the outcrop of the seams, and then working the outcrop coal right back to the surface, leaving practically no protection against the water which now pours into many of the workings during the rains. In a number of instances the whole of the outcrop coal has been quarried, leaving old surface-workings to fill up with water during the rains.
(b) The working-out of large areas into pillars without the provision of any system of panels or barrier, to form a protection against fire, water, or creep, or to enable the pillars to be worked within a reasonable time of their having been formed. In many cases when the time comes for the coal to be worked, there will be considerable loss on account of the coal round the faces of the pillars having perished.
(c) The originally small dimensions of the pillars and the steady reduction in their size, owing to pillar-robbing by miners and natural causes, have already resulted in large areas breaking down and being entirely lost, and this will continue in the future.
Much has already been done at the majority of collieries to place matters on a better footing; but the warnings of subsidence, fire, and explosion, during the past two years, although fortunately unaccompanied by serious loss of life, show that much can yet be done. Where new workings are to be laid out at greater depths, the arrangements whereby the coal can be most cheaply and effectually won, with due regard to the protection and safety of the workers and of other districts of the mine. will require most careful consideration.
As a whole, the coal-field is fortunate in having a good roof above all the seams. This condition, where the workings are shallow, has enabled liberties to be taken in the way of robbing pillars and driving wide galleries which otherwise would have had disastrous results. As the depth increases, and the question of weight becomes more prominent, far greater precautions will have to be taken than have been necessary up to the present.
In the future development of the deeper workings, it does not appear probable that there will be any radical change from the present system (bord-and-pillar) of working. Although the bord-and-pillar and allied systems have in England been almost entirely superseded by that of longwall, even in the thick-coal areas, the labour conditions in India are against the adoption of longwall unless under exceptional circumstances. As a rule, the workings are opened out by driving main or narrow galleries in the required direction, usually about 2 1/2 feet in width by 4 to 6 feet in height. This work is clone by a special class of men, who are paid a footage rate, or sometimes a combined coal-and footage rate. A second gang (or sometimes two gangs) of ordinary miners follows on behind the main drivers, and removes the side and floor coal necessary to give the galleries the requisite height and width. Good progress can be made in this way where there is not much water to be dealt with; but as a rule, and provided that the main drivers can be got to work as required, it will be found better to make the original main gallery of reasonable dimensions, say 6 by 6 feet. In the future, in order to deal properly with the question of ventilation, gas, gob-fires, etc., it seems likely that all workings will be laid out on a system of panels, and the main haulage-roads driven in the solid between two series of panels out towards the boundaries, the coal in each panel being got as soon as possible after completion, and the barriers brought back eventually after all the panels have been worked out. It is not advisable to allow the coal to remain in pillars for any great length of time, owing to the perishing which takes place round the edges; and, if possible, the working of the "brokens" should be started within 12 or 18 months of the completion of each panel.
Owing to the presence of jhama, dykes, and faults, each set of workings would have to deal with somewhat different conditions, and the laying-out of any particular area would depend on these points and on the dip of the measures. A further point which increases the difficulty of working, especially where there is water, is the disinclination of the native miners to work uphill, the moment the gradient. becomes greater than 1 in 5 or 1 in 6. This is due largely to their objection to having pieces of coal rolling clown on to their unprotected legs and feet.
(4) Haulage.-
About 90 per cent. of the workings, whether incline or shaft., lie to the dip, and consequently the ordinary main haulage system is that in most common use. Endless-rope systems, which might otherwise be adopted, are handicapped by the prejudice of the Indian miner, who as a general rule must have his tub waiting for him before he will start to cut any coal; and when that tub has been filled, will, unless there is another tub ready for him, wait until it has been taken away and a fresh tub brought in its place. About two tubs per day may be taken as a fair average for a miner working in the solid coal. Small main-and-tail sets, each dealing with the coal from one or more blocks of workings, will probably come to the front where deep or moderately deep shafts are being worked.
(5) Pumping.-
There is a large quantity of water to be dealt with in the coal-field, in addition to that which finds its way into the workings during the rains; and, in sinking a pair of deep shafts towards the centre of the field, not less than 400 to 500 gallons of water per minute would have to be reckoned with, while pumps of even double that capacity might be required to, ensure a safe margin. Up to the present pumps of the Tangye and Worthington types have had the field almost entirely to themselves, and the Tangye Special, with its advantages and its drawbacks, is to be found in almost every colliery, although owing to the need for larger pumps for shaft and other work many other types are now being introduced. Although in. one case electric sinking pumps have been made use of, it is probable that at the majority-of collieries steam-sets will be utilized, even where electric power is available, owing to the difficulty experienced in keeping the motor and pump in good order in the Indian climate during the periods when the set is out of use. With respect to main shaft pumps, electric examples already installed, whether of the reciprocating or the centrifugal type, have given excellent results; and where they can be given regular work, and have not to be laid off for long intervals, there is no question of their superiority over steam-driven sets. Regarding dip-pumps, as already stated, the bulk of the workings in all existing collieries lie to the dip, and consequently a large proportion of the water must be dealt with at the working-faces. With inclined workings and shallow depths the maintenance of steam-pumps close to the working-face has presented no special difficulty, as air-shafts are sunk at convenient points as the face of the workings advances; but with deeper shafts and more extensive workings the difficulty will increase; and, where electricity cannot be installed, the question of a compressed-air installation, or even of hydraulic pumping, will have to be considered. There appears to be an opening in some cases for small oil or petrol-driven sets, where no other power is available.
(6) Ventilation.-
This is a question to be dealt with mostly in the future, since up to the present there has been practically, no attempt made at artificial ventilation. In almost every case natural ventilation, sometimes assisted by the exhaust and escaping steam from the underground pumps and ranges of steam-pipes, is relied upon.
In the case of new shafts and workings there will be little difficulty in arranging for a fan, and in laying out the workings to the best effect; but, where there are already areas worked out, and no shafts except those already in use for winding, it will be difficult to introduce a system of mechanical ventilation without considerable expense. Those in whose charge the working of the collieries lie will have ample scope for their ingenuity in designing a scheme that will best suit their particular conditions. One of the results of the introduction of mechanical ventilation will probably be a need for further underground supervision and the employment of European overman, until such time as the native pit sirdar (overman) has been sufficiently trained to deal with the questions introduced by a definite system of ventilation.
(7) Cost of Working.-
Rates and costs, as compared with 10 or 15 years ago, have increased considerably. The high price obtained for coal, and the difficulty in obtaining labour during the years 1907-1909, raised the costs of working considerably; whilst the steadily increasing depth from which coal is being raised, together with the longer haulages required, are necessitating greater capital outlay per ton of coal raised. This will increase still more in the future, although the centralization of the points at which coal is being got, and the larger output obtained from each central shaft or incline, tend to keep down the capital-cost per ton. At a fully-equipped colliery the working-cost at present, apart from Calcutta charges, should amount to between 1Is. 10d. and 2s. 2d. (1 rupee 6 annas to I rupee 10 annas) per ton, out of which the coal-getter receives 10d. to 1s. (10 to 12 annas), the amount varying, however, very considerably with the conditions. The colliery costs vary greatly- from month to month with the fluctuations of output, which may oscillate as much as 100 per cent. between the worst and best months of the year. With regard to the future, there will be a tendency in India, as elsewhere, for costs to rise and rates to increase, while there will be additional charges clue to the necessity for providing further and better sanitary arrangements and good drinking-water for the miners. These points have already received attention from some of the companies, but much has yet to be done; and the provision of a water-scheme for the whole of the coal-field, in which direction steps have already been taken, will mean a considerable charge on the coal-industry of the district.
(8) Labour.-At present the mining community as a whole may be considered as almost entirely agricultural, the mining side of their lives being, from the aspect of the workers, only supplementary to their agricultural home life. Instead of being miners possessing plots of ground which they cultivate in growing paddy (rice) and other crops in their spare time, They are largely agriculturists, who in the periods between working on their crops (that is, ploughing, sowing, and reaping) supplement their earnings by coal-mining. This condition of affairs is in many ways very similar to the condition which prevailed in England during the Middle Ages, when the serfs and villains had to do so many days work in the mines every year for the owner of the property, after which they returned to their ordinary vocation-generally cultivation or stock-raising.
For the most part the homes of the miners are several days' march from the mines at which they work, and a constant force of recruiters has to be employed to bring in fresh miners and to keep in touch with and make arrangements for their return after their frequent visits to their home villages. The greater portion return regularly to the colliery at which they have been working, although there are many who are constantly on the move, working sometimes at one place and sometimes at another. The aim of the owners should be to induce the miners gradually to settle permanently in the district by giving them at first such land as they require for cultivation on suitable terms, and thus to bring up a class of miner who has never known any other home than that at the colliery where he has been working, and who will prefer to work regularly in the mines as a miner than in the fields as an agriculturist. In many places steps have been taken in this direction, but progress is bound to be slow, and it will be many years before an entirely mining class of native is created.
The question of bringing to a small area crowds of natures who have hitherto lived in isolated villages, with primitive systems of sanitation and water-supply--which, although tolerable in a comparatively thinly-populated area, are certain, if introduced into a crowded mining community, to ensure outbreaks of cholera and plague-is an important matter. Any steps taken to increase the density of the population must go hand in hand with the provision of a sanitation and water-supply scheme, and these are points which are receiving great attention both from the colliery-owners (" Presidential Address," by Mr. R. P. Ashton, Transactions of the Mining and Geological Institute of India, 1911, vol. vi., page 16.) and from the Government authorities. (The Coal District Sanitation Bill and The Coal District Water Supply Bill.)
The main breaks in the miners' year are, first, the Monsoon from May to July, when the miners go to their villages to plough their land and sow their crops; and, second, from the end of September to the end of November, when the paddy is ready for cutting. In consequence the outputs of coal are at their best from December to May, with a very great falling off from May to August, an improvement in August and September, and two very poor months in October and November. Indian coal does not stock well, and the effects of unequal raisings cannot consequently be neutralized by accumulating stocks during the good months and despatching from stock when the railings are slack. There is, therefore, an invariable tendency towards a wagon shortage during the cold weather (December to May), which shortage is accentuated by the inadequate facilities for dealing with the congestion of wagons in and around Calcutta and at the docks. The grain traffic, which also comes on during these months, helps to decrease the supply of available wagons.
(9) General.-
Other points in the future development of the coal-field, lend themselves to special consideration. In the separation and cleaning of the coal, the advantages to be gained by screening and picking are beginning to make themselves felt, and the provision of screening-plants suitable for Indian conditions will necessarily follow any future development. The main difficulties to be overcome in the design of a screening-plant for Indian use are the objection of the railway companies to any type of screen that crosses over the rails, and to the use of covered wagons for the conveyance of coal. These objections necessitate a special design of plant, and the use of telescopic and adjustable shoots which can be drawn back, when required, to a point well clear of any wagons which may be standing or passing on the line. So far as the question of coal washing has been entertained, it has been found that washing as a means of taking out the dirt from the small coal has little effect. The incombustible matter in nearly the whole of the Indian coals is so closely mingled with the coal, that the percentage of ash can only be very slightly reduced by washing. As a rule, the ash percentage of the small coal is rather lower than that of the steam-coal.
Some of the seams make a very fair quality of hard coke, the type of oven used consisting as a rule of two side-walls about 5 feet in height and ;10 to 40 feet in length. The walls are 8 to 10 feet apart, the ends being built up, while firing, with loose bricks. Flues are formed by passing rollers (wooden props) between the openings in the base of the side-walls through which the firing of the ovens is started, while the charging is being carried on. When the oven is ready for firing, these rollers are drawn out. Except during the rains, a very- fair quality of coke is made, but the process is wasteful, at least 2 tons of dust being used for each ton of fair-class coke made. No attempt has been made to introduce bye-product recovery ovens into this district, although there seems no reason, judging from the results given by those installed elsewhere, why they should not prove a success-, and why a good market should not be obtained for the coke and bye-products.
At present the amount of slack and small coal produced greatly exceeds the demand, and consequently a large quantity has in many place been left underground. It is chiefly in demand for brick-burning, an industry that prevails all over India during the winter months, namely, October to April. The sale of briquettes should be a profitable one, the present difficulty with regard to an installation being the high price of tar.
Mr. E. SEYMOUR WOOD (Murton Colliery) said that the paper was of great interest, and lie would have some remarks to make upon it at the next meeting. There was one very interesting feature, and that was the reference to the presence of micaperitlotite in the different seams that ran throughout both the Raneegunge and the Giridih coal-fields. It was one of the most interesting geological features of the Indian coal-fields that he had come across. There was no doubt that a great future lay before the field described by Mr. Greenwell.
The PRESIDENT (Mr. W. C. B1ackett) asked whether the “jhama" coal was capable of being burnt.
Mr. E. SEYMOUR WOOD said that "jbama" was really a cinder-coal.
Prof. HENRY LOUIS (Armstrong College, Newcastle-uponTyne) said that when he was out in India some 8 or 9 years ago they were making, so far as he remembered, coke in the Jherria coal-field in nothing but open kilns, and he would like to know whether anything had been done yet in the way of adopting beehive ovens, as there had been some talk of doing so at that time. With regard to the "jhama" coal, Sir Thomas Holland had pointed out that mica-peridotite was very much
more fusible than any of the other igneous rocks with which one was acquainted, and had ascribed this cindering of the coal over such enormous areas to the very great fusibility of that rock.
Mr. G. H. GREENWELL (Poynton, Cheshire) said that, so far as the Jherria coal-field was concerned, practically nothing had been done yet in regard to the question of installing beehive coke-ovens. In the collieries with which he had been connected a few had been put up as an experiment, but they had not proved entirely satisfactory.
The PRESIDENT (Mr. W. C. Blackett) said that the paper would be brought forward for criticism at a future meeting, and would, he hoped, provide an interesting discussion. Mr. Greenwell had communicated a paper containing many points of interest, and he had pleasure in proposing a vote of thanks to him.
The vote of thanks was heartily accorded.
