CHAPTER XVI.

COAL-CUTTING MACHINERY.

Advantages of Coal-Cutting Machines-Difficulties in their Adoption-Number in use in the United Kingdom and America, and Tons of Coal wrought by them-The Motive Power— Classification of Machines-Pick Machines: The Ingersoll-Sergeant, The WrightsonMorison, The Champion, The Morgan-Gardner-Bar Machines: The Jeffrey, The Hurd, The Lee-Disc Machines: The Gillott and Copley, The Rigg and Meiklejohn, The Clarke and Steavenson, The Diamond, The Jeffrey-Chain Breast Machines: The Jeffrey, The Goodman, The Morgan-Gardner-Chain Longwall Machines: The Goodman, The Morgan-Gardner-Stanley's Coal Heading Machine-Rails-Capital Expenditure-Length of Face Cut and Coal Obtained-Production per Man-Percentage of Round Coal-Rules for Coal Cutting Machinemen-Adaptability of Machines under varying Conditions.

THE labour of coal-getting is arduous even under the most favourable circumstances, and in thin seams it is especially severe and trying, owing to the constrained and unnatural attitude of the collier during the time he is at work, and more particularly at the work of “holing."*

It is considered allowable, with good and skilful hewing, to take a height not exceeding 9 inches for the holing when carried to a depth of 3 feet.

Where the holing is altogether in the coal, and the seam thin and hard, handhewing is placed at a great disadvantage, because the coal obtained as a result of the holing is much less than that obtained from the same depth of holing on thick seams, the labour of holing in which is much less. Coal-cutting machines have been designed, and are in use to some extent, for undercutting the coal. Where circumstances admit of their use they save the collier the heaviest part of his toil. There is, however, great difficulty in the general adoption of coal-cutting machinery, on account of the undulating character of the seams, and the resulting irregularities of roof and thill over very limited areas. These irregularities form great obstacles to the smooth working of coal-cutting machinery, besides. which, some districts are so much intersected by faults breaking the continuity of the coal-seams that machinery for getting the coal is quite out of the question. Other coalfields are more favourably situated in that regard.

COAL-CUTTING machines for holing have certain advantages over hand-holing, but there are difficulties met with in their adoption. The advantages are :—

(1) Reduced working cost, under favourable conditions of the coal-seam and its adjacent strata for cutting either the coal or the holing dirt under the seam, or the parting dirt between two coals of a seam. The thinnest seams, where the handgetting price is high, usually show the most economical results, but this is not always so. They are not likely to give economical results where coal can be worked by hand at 2s. per ton, or under, as the cutting price. A saving ranging from 4ď. to Is. 6d. per ton has been effected by the use of cutting machinery, and Is. per ton appears a reasonable average where it is carried out on an extensive scale.

*

"Holing” and “undercutting" are synonymous terms signifying the cutting in, under, or above a seam, so as to render possible its after dislodgment by wedging or by means of explosives. In the North of England the word "kirving" is used in the same sense, but is generally applied to the shorter undercuts obtained in the pillar and stall workings.

(2) A greater proportion of large coal is obtained. In the case of a thin seam under which the holing dirt is too hard for hand work, the seam can only be handworked by holing in the coal. By introducing machines, the holing in the dirt can be accomplished. In the hand-holing the cuttings represent a considerable portion of the seam, and reach the surface as small coal, while with the machineholing the yield of the seam is almost entirely round coal. Again, in the case of a thicker seam, free from interstratified bands, in which it is necessary to hole in the coal both by hand and machine, the small coal from hand-cutting is greater in quantity than that from the machine-cutting, owing to the shape of the underThe section of the coal cut by hand-holing is in the form of an irregular right-angled triangle. The width at the beginning of the cut will vary with the depth of the undercut. Even a skilful workman requires to take out a width of 9 inches at the front to enable him to get underneath for a depth of 3 feet, and in the case of greater depths the width will vary from about 21 inches at the front to nothing at the back.

cut.

The section of the coal cut by machine-boring is in the form of a rectangle, the width being uniform, with disc machines from 3 to 5 inches, and with barmachines may run from about 74 inches at the front to 3 inches at the back of the cut. A much larger area of the coal is thus cut away in the form of small by hand as compared with that cut by the machine. The quantities of small made by hand and by machine in seams where the holing in the dirt can be accomplished by either will be practically the same. If, however, there is a considerable difference between the quantity of small made by hand-holing and by machineholing, there will be a material difference in the total value of a given area resulting from the selling price of the coal. The difference in the value of large and small coal varies in different districts, but will probably average 5s. per ton. The increase in the proportion of round coal obtained in cases where machineholing has displaced that by hand ranges from 5 to 20 per cent., the average being about 10 per cent. Thus if the yield of round coal obtained by hand was 70 per cent., and increased to 80 per cent. after machine-holing had displaced hand-holing, the increase would be 10 per cent. If the whole of the seam is made into coke, there is no advantage whatever from any saving in the quantity of small made. At collieries where the coals are sorted into a number of varieties, each of which has its own market value, it is difficult to determine what proportion of the coal obtained in the undercut should be classed as small, there being a higher value for the lowest sorts of large. In many cases, however, a higher price is obtained for machine-got coals than for those worked by hand. If we take the case of a colliery whose output is 500 tons per day, or, say, 150,000 tons per annum, in which the introduction of coal-cutting machinery ensures an increased price of Is. per ton for the product and a decreased price of 1s. per ton in the cutting, there would be an increased return of 25. per ton realised. Against this must be taken the cost of motive power, repairs, and interest on capital, which may amount to, say, 6d. per ton, leaving a net increased return of 15. 67. perton. Upon an output of 150,000 tons per annum this represents an additional profit of £11,250. (3) Fewer men are required to work at the face, for each machine introduced to a longwall working reduces the number of men engaged in holing from 20 to an average of 3, and the attendants on coal-cutting machines work in greater safety than do hewers with the pick. The former, from their position of working, are better able to make observations of their surroundings than the latter, and therefore better able to guard against accidents from falls of the roof at the face. There is thus an actual money saving, because there are fewer claims under the Workmen's Compensation Act.

(4) With coal-cutting machines the face can be advanced more rapidly and more regularly than with hand-hewing. The desired line of longwall face is thus better maintained, for there are differences in the rate of advancement made by

hand-hewers in a district. The accelerated rate of advance is of considerable importance in seams with a tender roof, enabling the workmen to pass quickly into fresh positions as subsidence of the strata causes falls of roof.

In Scotland the standard of production for a coal-cutting machine is taken at 100 tons per shift. For a given output, less pit room is required for machine work than for hand labour.

(5) In districts where it is necessary to build houses for the workmen as the colliery develops, the use of coal-cutting machines lessens the number of men employed, and also the amount of capital required to sink in the building of houses. The cost of the coal-cutting plant is thus returned in the reduced capital required for workmen's cottages.

The difficulties are:-(1) The trying conditions under which machines work. In longwall the road for the machine to travel and work upon is generally laid alongside the face, and has to be moved and laid in a fresh position immediately the coal directly in front of it has been removed. The road most suitable for quickly taking up and relaying is here in use. It is not laid with the firmness of a permanent road, but must be of a portable description. A disc machine works with a considerable side-thrust, and would work more advantageously on rails more solidly laid. Where there are many undulations in the seam being worked, the road along the face is laid with many changes in the gradient through the hollows or inequalities of the floor, and, as the machine travels through these, frequent stoppages occur. In seams having a regular dip in a certain direction the road alongside the face may be kept at one uniform gradient, with the line of the road straight, and consequently the runs with the machine will be uninterrupted. Owing to difference in these conditions, the number of yards cut per hour must vary with the same machine.

(2) Another difficulty is the dust of the mine. It is necessary that the spindles which revolve in bearings of the machine be kept properly lubricated and free from grit. But, despite precautions taken, it is difficult to keep all fine dust from getting into the machines. Grit between the surfaces in contact produces friction, and wear follows. As the bushes and the wheels wear, the misfitting portions of the machine cause more frequent stoppages. Wear is also produced by unequal pressure upon one side and another of a particular shaft due to the machine working upon an uneven floor or on an incline.

(3) Delivering motive power to the machine. The only methods of driving coal-cutting machines now in use are by compressed air and by electricity. Both compressed air and electricity are troublesome to convey from the main lines of service, pipes or main cables, to machines which have to be in motion and constantly changing their position at the face. The pipes or cables laid from the main roads to follow the moving face are liable to accidents from falls of roof or coal, or from cutting in the careless handling of tools.

(4) Obtaining efficient attendants for the machines. The attendants require to be practical miners, accustomed to be always on the alert to guard themselves from accident by properly fixing timber at the face, and to test the roof and coal for signs of impending fall, and must further have some knowledge of the special machines placed in their charge, so that they may repair slight damages which may occur during the use of the machines, and efficiently examine them at intervals throughout the working day. This difficulty will probably pass as the young miners are trained and the coal-cutting machines become more generally used. (5) The opposition of the workmen, arising from prejudice against the introduction of machinery to displace a certain amount of labour, and an inability to see the advantages of lessened danger to themselves and relief from the most trying and arduous of the labour performed in the mine.

(6) That of applying a coal-cutting machine under a weak roof. The continual taking down and resetting closely-ranged timber adds to the cost of working, and

may increase it beyond that of hand labour if stoppages are so frequent as to allow of but little working of the machine.

The number of coal-cutting machines, and the quantities worked, are given in the following tables, compiled from the reports of the inspectors of mines for 1900. Some of these machines were working only irregularly, and the coal wrought by the 311 machines amounts to the slight total of 3,321,012 tons, or not quite 1 per cent. of the total output of 225,170,163 tons.

The disc machine has hitherto been mostly used, as shown by the following table, which, although incomplete, gives a good idea of the machines most favoured:

The number of machines in use in the United Kingdom has increased since the year 1900 (see table below), there being 345 at the end of 1901. The late

NUMBER OF COAL-CUTTERS IN USE IN THE UNITED KINGDOM IN 1900.

Sir Clement le Neve Foster in his annual report stated that in 1902 483 machines were in operation at 166 collieries, producing in all 4,161,202 tons.

In America, the conditions of the coal mines are more favourable to the use of the mechanical coal-getter, and consequently a large number is in active operation there. This is shown in the following table, which, however, refers to 1899, whereas that given for British mines is for 1900:

NUMBER OF COAL-CUTTERS IN USE IN AMERICA IN 1899.

* A short ton (2,000 lbs. avoirdupois) = ·8928 of a long ton (2,240 lbs. avoirdupois).

From this table it appears that the 3,125 machines in use in 1899 mined 23.12 per cent. of the total bituminous output.

In 1870, the total coal production of the United States of America was 32.863,000 long tons, while that of Great Britain was 110,431,192. So much more rapid was the rate of increase in America, that in 1899 for the first time that country produced more than Great Britain, the figures being 226,553,564 tons and 220,094,781 tons respectively. In 1900, America doubled the lead she had over Great Britain in 1899. There has been great increase in the number of machines used in America since 1890. In 1891, there were only 545 machines mining coal; in 1899, there were 3,125 in use.

The total number of persons employed in coal mining in Great Britain in