Uxmn 1, 1887.] 



♦ KNOWLEDGE ♦ 



99 



offspring. Every farmyard combat between cocks illus- 

 trates the truth of Schiller's lines : 



Jleanwhile, until philosophy 

 Sustains the structure of the worlil, 

 Her workings will be carried on 

 By hunger and by love. 



And among the larger animals — as stags and deer, and 

 notably fur-seals * — the deadliest combats take place at 

 certain seasons for possession of the females. But there is 

 competition less fierce in character, if not less fatal, to the 

 weaker or unendowed, strength giving place to grace of 

 form, brightness of colour, and witchery of song, the females 

 making choice of the male that attracts them most, or, as 

 among the highest species, where he has wealth or good 

 social position. These condone infirmity- and ugliness. 



Sexual selection thus explains the development of special 

 features which, transmitted in increasing degree through a 

 series of generations, have contributed to the survival of the 

 fittest. For whatever these features may be, whether 

 weapons of defence or attack, plumage and song of birds, 

 colours of butterflies, perfume as of the musk-deer, or acrid 

 taste as of the toad, their presence is explained by their 

 titility, since, as with the flowers and scents wherewith 

 plants attract insects to secure fertilisation, the primary 

 function of colour, form, ornament, and whatever else has 

 given advantage to plant or animal over its competitors is 

 its service to the organism, and not, as man in his conceit 

 has assumed, the delight or profit which it has given to 

 him. 



COAL. 



By W. ilATTiEu Williams. 



SSUMIXG that the seam is reached by the 

 methods already described, that the roads 

 are made for carrying it to the shaft, we 

 now require to learn how the collier cuts 

 up the seam into the portable lumps with 

 ■which we are all familiar. The usual mode 

 is by what he calls '• holeing,' which, if I 

 am not mistaken, is another mining technicality of Scxin- 

 dinavian origin, as it is not by any means making a hole, but 

 is undermining in order to overthrow, and Iiolj'a and hvolfa 

 are Icelandic. verbs signifving to turn over or overthrow. 



The mooe of holeing is to undermine the seam by cutting 

 a groove along the lower part of the coal or the bed of rock 

 that underlies it. This is made as narrow as possible to 

 save labour and coal, and extends horizontalh' under the 

 seam to a distance of two or three feet, as far as the collier 

 can freely reach with his pick, which is made narrow and 

 sharp for the purpose. The position of the worker when 

 holeing is apparently very awkward and constrained. He 

 lies on hLs side or squats sideways, and swings the pick 

 horizontally, delivering several smart blows before he 

 scrapes out the fragments he has made. In thin seams 

 his position appears most painful, but he endures it 

 patiently, without grumbling more than other men grumble 

 at their daily labour. 



In colliery districts where the prevailing seams are less 

 than five or six feet thick, this mode of working, and the 

 constant habit of accommodating the body to a low roof, 

 has developed an interesting muscular modification. If the 

 reader should be passing through such a district, he may 

 dLstinguish a collier in repose from any other member of the 



* Cf. Elliott's "An Arctic Province," ch. x, for a vivid account 

 of the battles between the males for priority on the breeding- 

 grounds of the I'ribylov Islands. 



population. His favourite position is to squat on his heels, 

 leaning his back against a wall, just as he rests underground 

 during the merry dinner hour. On a bright Sunday after- 

 noon he squats in this queer attitude against the wall by the 

 side of his cottage door, supremely happy in the enjoyment 

 of his short pipe and the rare luxury of bathing in the sun- 

 beams. 



Thus undermined, the coal either breaks down by its own 

 weight, or is thrown down by driving wedges into it a few 

 feet apart by means of heavy hammers, or boring holes (this 

 is not called holeing) with a drill and blasting with gun- 

 powder. 



Blasting with gunpowder is of course inadmissible where 

 there is any liability to accumulation of fire-damp, but as 

 the cutters are paid by piece-work, the temptation to adopt 

 it is very great, because much more can be thrown down 

 with a given amount of labour by blasting than by wedging. 

 Thus is sometimes presented the anomaly of miners carrying 

 safety lamps and blasting with gunpowder in the same 

 working. Mr. Galloway has shown by a long series of 

 careful investigations that the danger of blasting is by no 

 means limited to pits or workings containing explosive 

 gases. A working may be quite free from these and yet an 

 explosion, with fatal consequences, maj' follow an ordinary 

 blasting shot. This happens when there is much dry coal- 

 dust accumulated in the imm''diate neighbourhood of the 

 shot and extending far beyond. Each of the millions of 

 minute p:irticles takes fire by combining with the oxygen of 

 the air, and fires its neighbour, the combined result being 

 an evolution of a great volume of carbonic oxide and 

 carbonic acid gases, and gaseous water, as well as a destruc- 

 tive outburst of flame ; the expansion of the gases driving 

 the flame along the workings with a force and velocity 

 comparable, though inferior to, the generation and propul- 

 sion of ignited gunpowder gases through a gun. 



]\Iany substitutes for gunpowder have been proposed. 

 One of the most promising is that of using the expansive 

 energy of the chemical union of water with quicklime. 

 When the hydrate (slaked lime) is thus formed a consider- 

 able increase of liulk occurs. By filling a bore-hole with 

 lime instead of gunpowder, then tamping or plugging and 

 adtnitting water by permeation, the expansion of the solid 

 lime exerts a disruptive force like that of the expansion 

 of the gases evolved by the combustion of the gunpowder. 



Some seams are cut at the middle or top and wedged 

 accordingly. There may be various reasons for thLs. Thus, 

 in working the Flintshire cannel, which consists of two beds 

 — the smooth cannel and the curly cannel — it was customary 

 when I was there to hole into the top, and wedge up from 

 the bottom, because the upper smooth cannel has a much 

 smaller value than the curly below it, and is much softer 

 than the bituminous shale which is below the curly cannel. 

 That part which is cut away in the work of holeing is, of 

 course, reduced to slack, and is of little value — so li'tle that 

 I have seen it freely used for ballasting railway sidings, 

 being cheaper on the spot than gravel or stony soil. 



A great deal of this slack is now utilised by making it 

 into " patent fuel," i.e. blocks formed by conglomerating the 

 fine fragments by means of pitch or tar or other binding 

 material, aided by pressure, or even by great pressure alone. 

 Square liricks or cubes as large as may be conveniently 

 handled are thus formed, the value of which is well appre- 

 ciated b}' those who ha^■e travelled far in steam-packets, and 

 know the grimy horrors of ordinary coaling, as compared 

 with the cleanly shipment of these blocks. Their compact 

 stowage is a further great advantage. 



It is evident that if the whole of a seam of coal were thus 

 cut away and removed at random over a wide area, the rock 

 above would fall in and bury the miners. The simplest 



