De 



1885] 



NATURE 



ing-engines which, as monuments of mechanical skill, merit the 

 careful inspection of all interested in mining industry, are most 

 important additions to the safety appliances provided in the 

 present day in connection with the pit work of our mines. To 

 these must be added the improvements made in signalling 

 arrangements from the surface and underground, in connection 

 with which electricity has of late commenced to play an import- 

 ant part. 



The great advance made in the ventilation of mines during the 

 past half century is well known to all who have paid the least 

 attention to these matters. Not only has the ventilating furnace 

 been greatly improved in efficiency and power ; the steam jet 

 and compressed air have received important application within 

 the last thirty-si.x years, and fans, and other mechanical ventilat- 

 ing agents of great power have come into extensive use during 

 the past twenty-three years. 



The proper distribution of the air which is drawn down into 

 the pit, and the arrangements necessary for insuring the distri- 

 bution of fresh air throughout the different roadways and work- 

 ings in a mine, and its isolation from return- or foul air- 

 currents which are passing to the upcast or exit shaft, are now 

 carried out effectually in a large proportion of our coal 

 mines. 



Although we have long been familiar with the nature of fire- 

 damp, and with the generally-accepted explanation of its origin 

 in coal, considerable uncertainty and consequent diversity of 

 opinion still prevail as to the condition in which the gas is pent 

 up in coal, and in the associated strata. That the light car- 

 buretted hydrogen, which chiefly composes fire-damp, exists, 

 with its associated gases, in a more or less condensed condition, 

 in coal, even some time after removal from the pit ; and, that 

 the gradual escape of the condensed inflammable gas from coal 

 has constituted a fruitful source of disaster to coal-laden ships, 

 and to steam-vessels carrying a large provision of coal — such as 

 our ships of war — are very well known facts ; but, there are 

 constantly-recurring phenomena connected with the escape of 

 gas from coal, a really satisfactory explanation of which is still 

 wanting, although patient inquiry has long been devoted to its 

 discovery. Thus it has been demonstrated by experiment that, 

 if cavities are bored into the coal and plugged, the gas will 

 speedily accumulate so as to exercise a pressure of several 

 hundred pounds upon the square inch, as indicated by pressure- 

 gauges fixed into the cavities. 



In some localities, the gas issues as a jet, or so-called "blower," 

 and many of these furnish a continuous supply of gas under 

 fairly uniform pressure, which may be conducted in a steady 

 stream to the surface, and utilised for heating and even for 

 illuminating purposes. Many explanations have been offered of 

 the existence of these blowers, and of the maintenance and 

 sudden cessation of the gas supply, but they have remained a 

 mystery. 



The systems of ventilation now in use in coal mines, and the 

 powerful circulation of air maintained thereby, deal effectually 

 with the removal of gas, as it exudes from frtshly-worked coal 

 even in very fiery mines, when it passes into the main ways and 

 the workings which are actually in use ; but, in old workings, 

 recesses, or cavities, and in the so-called goaves, where the 

 worked-out space has been filled up with stone and ditiris, the 

 gas may lurk and lodge, and may at any time constitute a source 

 of great danger, if special means are not adopted to favour its 

 removal ; and, even with the most efficient and searching venti- 

 lating arrangements, the almost unavoidable existence of some 

 accumulations here and there in mines where fire-damp is 

 prevalent, renders absolute freedom from it, of the air in the 

 mme, practically unattainable in such cases, although the amount 

 diffused through the atmosphere may seldom, under ordinary 

 conditions, approach, even distantly, to the minimum proportion 

 which, per se, might constitute a source of danger. 



It is now generally admitted that variations of atmospheric 

 pressure influence the tendency of fire-damp to escape from 

 goaves or old workings in a mine where accumulations are liable 

 to exist, and that when a reduction of pressure suddenly sets in, 

 such an escape may take place even to some considerable extent 

 before the barometer indicates the depression. Some even 

 maintain that the emission of gas from the fresh face of coal 

 IS considerably promoted by such alterations of jiressure ; but 

 although there are many undoubted instances of explosions 

 having occurred during sudden and very considerable depressions 

 of the barometer, different observers in this and other countries 

 are by no means in accord as to the extent to which, in a 



properly-ventilated mine, the existence of fire-damp in the air is 

 influenced by barometric changes. 



There are some mines so free from fire-damp that naked lights 

 may be used therein with perfect safety, and others where the 

 use of safety lamps need apparently be only insisted upon in 

 certain parts of the workings. There can be no doubt, on the 

 other hand, that the adoption of even the most perfect ventilation 

 cannot secure such absolute safety as to render the use of naked 

 lights warrantable, where seams are worked in which fire-damp 

 exists in any abundance, — because danger may there arise at any 

 time, from some accidental stoppage or partial failure of the 

 ventilating arrangements, from the effect of a reduction of 

 atmospheric pressure in promoting the escape of gas from lurk- 

 ing places, or, from a liability to the sudden emission of gas in 

 considerable quantity from coal. The very poor light furnished 

 by the forms of safety lamp still chiefly in use, has afforded very 

 strong temptation to the men to have recourse to naked lights, 

 and to the managers of mines to regard such proceeding with 

 inditlgence, even where its danger is well recognised. Poor as 

 the light is which the older forms of lamps furnish in a quiet 

 atmosphere, it becomes even much worse when they are exposed 

 to such cuiTents as are now met with in properly ventilated 

 mines. 



Efficient lamps should therefore burn brightly and steadily even 

 in strong currents of air, and they should be unable, under any 

 circumstances at all likely to arise in coal mines, to ignite an 

 inflammable mixture of fii-e-damp and air, even when this is 

 passing at the highest velocities which can occur in any part of 

 a mine. 



The importance of determining how far modifications of exist- 

 ing lamps, or new kinds, fulfil these conditions, has led individuals 

 specially interested in the subject, and associations of raining 

 engineers, for many years past, to submit lamps to comparative 

 experimental tests ; and the first branch of inquiry which was 

 taken up by the Royal Commission was the systematic comparison 

 of the behaviour of different lamps under variously modified 

 conditions in currents of explosive mixtures of gas and air, 

 travelling at different and accurately-determined velocities. 



As the experiments proceeded, and the results of tests applied 

 to particular lamps became known to the makers, modifications 

 in construction were introduced, or new an'angements devised. 

 More than 200 lamps have been submitted to a variety of trials, 

 and even up to the present day the Commission have continued 

 to receive new lamps, with urgent requests that they should be 

 included in the trials. 



This investigation has also included a careful determination of 

 the amount of light furnished, and of the burning qualities of 

 all the more promising lamps, as well as an examination into 

 their practical merits, in regard to construction, weight, and 

 handiness. 



The results of these extensive investigations will now very^ 

 shortly be in the hands of the public : I must content myself 

 with veiy briefly indicating their general nature. 



Only three types of lamp were until recently in extensive use 

 in this country : the original safety lamps, which the miners owe 

 to the genius of Davy and of Stephenson, and a lamp not long 

 afterwards devised by Dr. Clanny. When the safety lamp was 

 first invented, the ventilating currents in mines were very 

 moderate indeed, and under the then prevailing conditions these 

 earliest lamps were fairly safe. But, at the present time, the 

 air in the mine roadways often travels at a rate of 20 to 25 feet 

 per second, and may even, in some special places, attain veloci- 

 ties of 30 to- 35 feet. Under these conditions the Davy and 

 Clanny lamps cease to afford any security in localities where 

 fire-damp is prevalent. This had already been indicated by the 

 results of previous experiments when the Commissioners com- 

 menced their work, but their own investigation so clearly esta- 

 blished the great danger of these lamps, and the facts already 

 known on the subject appeared to have received so little 

 consideration, that the Commissioners regarded it as their 

 imperative duty to direct the Home .Secretary's attention 

 officially and in strong terms to the fact, in the hope that most 

 prominent publicity would be at once given to their warning. 



After some delay, a circular embodying the substance of it 

 was issued, but without any indication that it bore the authority 

 of the Royal Commission. This action was taken not long 

 after the appointment of the Commission, yet the Davy and 

 Clanny lamps have continued in use in mines where the elements 

 of danger insisted upon exist. 



The Davy lamp had, some years back, been rendered much 



