150 MACHINES FOE CUTTING COAL IN MINES 



not one machine that approached nearer to success than the invention of Michael 

 Menzies. 



' This fact is not referred to in disparagement of the patentees, for there -were many 

 curious devices, ingeniously arranged ; but the matter is referred to to show that the 

 object excited much continuous interest, and that amongst so many miscarriages, our 

 mechanics were still hopeful. 



' Amongst these devices may be enumerated the " saw," " catapult," " battering 

 ram," "plough," "rotary wheel," "endless chain," "planing machine," and many 

 others by which the coal was to jse either crushed, cut, or shared out. 



' There had been no suitable power made known for driving the machines ; and it 

 was to that cause, without doubt, that so many failures and disappointments were 

 attributable. The steam-engine, even when it attained to its most perfect form, is 

 not in itself sufficient for the purpose, because steam cannot be produced near to the 

 place where the work has to be done, nor can it be carried long distances in an effective 

 condition, by reason of its rapid condensation. Moreover, an escape of exhaust-steam 

 could not be permitted in the coal-mine, because of its tendency to soften and bring 

 down the roof, the difficulty of maintaining which is already the most serious and 

 troublesome part of coal-mining operations. 



'Hydraulic power might, in certain cases, be, and has been recently, tried, but its 

 unfavourable conditions exceed its advantages for the purpose of cutting coal in mines, 

 ,ind may be put aside from present considerations. 



' But in compressed air, in so far as the moving power is concerned, every require- 

 ment is found ; and from the date of the experiments made at West Ardsley in York- 

 shire, in 1862, the question was undoubtedly settled. 



'The elastic property of air under compression, is an old and well-known power; 

 but until these experiments had been completed, its value was but imperfectly under- 

 stood, and its future beneficial influence on coal-mining was unappreciated. 



' The engine for compressing the air, by which a coal-cutting machine is worked, is 

 generally placed on the surface, near to the top of the shaft ; a receiver is fixed in close 

 proximity thereto, and the air is taken from the compresser to the receiver, which is 

 30 feet in length and 4 feet in diameter. 



' The density is generally of about three atmospheres. 



' Iron pipes of sufficient area are laid on from the receiver to the bottom of the shaft, 

 and there, being split into smaller sizes, is led in every needed direction through the 

 roads and passages of the mine, exactly as the gas and water services are laid on in 

 any town. 



' At the entrance into the working places, screw joints or stop-cocks are fixed to the 

 iron air-pipe, at which point an india-rubber nose, 50 or 60 yards in length (as the 

 length of the " benk " may require) is screwed on ; the other end of the nose is attached 

 to the cutting machine, and when all is in readiness, the tap at the receiver is turned 

 on, and the air rushes down, and throughout the whole service of pipes. 



' The air does not require to be forced from the receiver, for by its own elasticity it 

 is carried forward at a velocity corresponding to its own density. 



' Apparently it loses, if the arrangements are good, but little of its power by 

 distance, except the frictional retardation ; and machines are working underground, 

 at nearly two miles distance from the air-engine, without any serious loss of 

 force.' 



Firth's Coal-Cutting Machine. A machine which maybe simply described as a pick 

 placed horizontal!}', and worked by a crank motion, has for some five or six years 

 (1874) been steadily at work in the West Ardsley collieries. The colliers, who at first 

 objected to ' following the machine,' instead of working with their old implements, 

 have at length yielded to the evident advantages of the ' coal-cutter,' and in many of 

 our largest collieries these machines are now fairly introduced. 



We must now turn to the consideration of this machine for cutting the coal, as 

 invented by Mr. William Firth. Fig. 1413 shows its form and construction; the 

 weight is about 15 cwts. for an ordinary sized machine, its length 4 feet, its height 

 2 feet 2 inches, and a gauge 1 foot 6 inches to 2 feet ; it is very portable, and easily 

 transferred from one ' bcnk ' to another. 



The front and hind wheels of the machine are coupled together in a similar manner 

 to the coupled locomotive engines. The 'pick 'or cutter is double-headed, whereby 

 the penetrating power is considerably increased. 



The groove is now cut to a depth of 3 feet to 3 feet 6 inches at one course, whereas 

 oy the old form of a single blade, the machine had to pass twice over the face of the 

 coal to accomplish the same depth. The points are loose and cottered into the boss, 

 so that when one is blunt or broken, it can be replaced in a few minutes. It dispenses 

 with the necessity of sending the heavy tools out of the pit to be sharpened, and is an 

 immense improvement on the old pick. 



