M I N E. 



VcniiU. 

 tion. 



Mine* of tjnct flame than candles of a large size, with a thick 

 wick. The size generally used is at the rate of 20 in 

 the poun ; but when inflammable air abounds, 



tliey are not thicker than a common black lead pencil, 

 there being from 40 to (JO of them in the pound. 



IP tryii.g the quality of the air by the flame of a 

 candle, the candle is trimmed by taking off the coal or 

 snuff from the wick, so as to produce a clear, distinct, 

 and steady burning flame. II a candle is thus prepared 

 and looked at in common air, a distinct well defined 

 cone of flame is seen, of a fine sky-blue at the bottom 

 next the wick, and of a bright yellow from thence to 

 the apex of the cone ; which cone of flame is vesicular, 

 and not a full body of burning matter as it appears to 

 the eye. Besides this appearance, there is another 

 surrounding the cone, which the brightness of the flame 

 prevent-' the eye from discerning. This may be seen 

 by placing one of the h::n 1 - expanded as a screen be- 

 twixt the eyes and the candle, and at the distance of 

 about an inch, so that the least point of the apex of the 

 yellow flame be seen and no more. My this arrange- 

 ment a top. as the miners term it, will be distinctly 

 observed cloae to the apex of the yellow flame, from an 

 eighth to a quarter of an inch in length. This top is 

 of a yellowish brown colour, and like a misty haze. 

 This haze is not only seen on the top. but it extends 

 downwards and surrounds the flame fully half way, 

 about a twentieth of an inch in thickness ; here it as- 

 sume* a violet colour, which passes into a beautiful blue 

 at the bottom next the wick. The test of the state of 

 the air in mine*, or " trying the candle," as practised 

 by miners, depend* entirely upon the appearance this 

 vapour or base assumes as to shape and colour at the 

 top of the flame. The top has distinct and different 

 appearances when burning in atmospheric air. carbo- 

 nic acid, azote, or carburetted hydrogen, with many 

 variations and modifications, according to the abun- 

 dance of any of these gases or their mixtures. 



When azote, or carbonic acid gas abounds, the top 

 ii frequently an inch or two in length, of a decided 

 brown colour, and the flame shortens and burnt dimly. 

 If these gates abound, the flame goes out, and the 

 miners retire. No sudden catastrophe arises from 

 these gases in the ordinary course of working mini 

 ia the carburetted hydrogen which rrqiiiri-a the utmost 

 m ami circumspection. 



When inflammable air i * opposed to exist in consider- 

 able quantity, the miner trims his candle and proceed* 

 with cautious step, holding the candle with the left hand 

 and screening the flame with the other ; a* this gas floats 

 in the upper part of the mine next the roof, he holds 

 the candle at low a* he can, and, keeping his eye fixed 

 MI the lop, advances. If the gas is in very small quan- 

 tity, he reaches the forehead without observing any 

 material change upon the top. But if upon advancing 

 a before mentioned, the top begins to elongate and as- 

 sume a bluish-grey colour, the miner is instantly on hi* 

 guard, advances with additional caution ; and, it'll 

 begins to spire, he kneels on one knee, and, holding 

 the candle near the pavement, gradually raises it up, 

 and observes the change which takes place on the top 

 at it approaches the roof. If the gas is abundan' 

 flmt elongate* into a sharp spire, and also the top. 

 is in general reckoned dangerous when the top 

 changes from the bluish grey to a fine blue colour, ac- 

 companic-l irr.inous points, whii 



upward- n\c and top. When the 



symptoms are very evidently dangerous, a sudden move* 

 1 



n:ent of the hands or body is liable to produce ignition ; 

 the experienced miner, in this case, slowly and cautious- 

 ly lowers his candle to the pavement, and then, turnini* 

 round, makes his retreat slowly, or slips up his hand and 

 extinguishes the flame. If the miner ventures too far, 

 and approaches the body of gas at the exploding mix- 

 ture, the top rapidly elongates, and the flame of the 

 candle rises in a sharp spire several inches in length, 

 when in an instint the whole surrounding gas is in u 

 blaze, an explosion ensues, and the extent of the de- 

 structive ravages depends upon the quantity of the 



tion 



. 

 This " trying the candle" requires caution, and great 



experience, particularly in not advancing too far with 

 strong igniting symptoms upon the flame, where the 

 lives of so many men, and the prosperity of the colliery, 

 are at stake. No precise rule can be laid down which may 

 be universally depended upon ; all that can be stated 

 here are general facts. Almost every colliery, after hav- 

 ing been wrought for some time, gives a peculiar top 

 to the candle ; so that while in one colliery ai> explosion 

 will take place with a top lets than an inch long, in ano- 

 ther colliery tl* top will be two inches long, and the 

 air considerably under the igniting point. These diffe- 

 rences depend upon several circumstances. If the gas 

 has not run through a long course of ventilation, and i* 

 free from mixtures of air, it will ignite with a very short 

 top ; while, on the other band, the gas which has run 

 through a ventilation of 20 or SO miles, will bear long 

 top without the least danger. From this it is 

 dent, that a well-tried experience, and thorough 

 practical knowledge, can be the only guides in these 



Formerly, when the air in a colliery was at the ex- 

 ploding point, and no thorough ventilation could be 

 produced, it became ima*iiji to carry forward the col- 

 liery by means of other light than that of a lamp or 

 candle. This was effected by the collision of flint and Stc*l-mill. 

 steel, produced by an instrument named a steel mill. 

 It is composed of a small frame ol' iron with a wheel 

 and pinion, which produce a quick motion of a disk of 

 stet-1 placed vertically, against the periphery of which 

 a piece of flint is held. 1'his machine produced suffi- 

 cient light to guide the miner in III- operation* ; but it 

 was very expensive, as every workman required a per- 

 son named a miller, to give him light. This light was 

 safe in comparison with tht of tlie candle, when the 

 air was dangerous ; yet, in particular cases, explosions 

 have taken place from it ; and although the steel mill 

 i* now happily su]>ereded by the safety lamp, the trial 

 of the candle must in many cases be resorted to, parti- 

 cularly in sudden emergencies, arising from the inflam- 

 mable air coming suddenly off while a collieiy is 

 working with candles, and judged perfectly safe. It 

 is for tin* reason the detailed account is given, such 

 test being less or more resorted to in many collieries 

 every day, though it ought never to be tried in danger- 

 out cases on any account whatever, except from absolute 

 necessity, as safety lamp* can be used with great ex- 

 pedition, and w'tli the most complete security. Previ- 

 ous to the invention of the lump, the whole mines of 

 extensive collieries have been carried on with no other 

 light but that produced by steel mills, as no candle 

 could be taken into the mines without producing 

 plosion. Thisnimlf of working tlie mines was attend- 

 ed with an uncommon cxpence, great inconvenient y, 

 niul imminent danger. This shews also the high va- 

 lue of the safety lamp in an economical point of view. 



