VENTILATION. 



working in it, and when driven by a fufficient force, this has 

 great power. 



Mr. John Taylor, in the Tranfaftions of the Society of 

 Arts for 1 8 1 o, has defcribed a method of effefting this procefs 

 more eafi'v, by attaching an air-pump of a very fimple con- 

 ftruAion to a fmall fall of water. The engine difcharges 

 more than two hundred gallons of air in a minute, and a 

 ftream of water fupplied by an inch and a half bore falhng 

 twelve feet is fufficient to keep it regularly working. This 

 method may be introduced with great advantage into narrow 

 pafTages or wells, but would be obvioufly inadequate to 

 ventilate the immenfe excavations in coal-mines, except it 

 were direfted only to fome confined part of the works. In 

 metalliferous mines, the generation of the fire-damp is much 

 lefs frequent than in coal-mines, and the extent and pofition 

 of the excavations make the ventilation of the latter a 

 labour of much greater difficulty. The moft valuable beds 

 of coal in England, with the exception of Staffordfhire, are 

 from two to nine feet in thicknefs, and they rarely incline 

 more than about fifteen or twenty degrees from the horizon- 

 tal level, and are frequently nearly flat. Each pit has two 

 (hafts or wells, called the doiuncajl pit and the upcajl pit. 

 The excavations or paffages in the coal, which communicate 

 from one pit to the other, are frequently not lefs than forty 

 miles or more in length, through which circuitous route the 

 air has to take its courfe, though the diitance from the 

 downcaft to the upcaft (haft, in a right line, may not be 

 more than a few hundred yards or feet, or even much nearer. 

 And here we cannot but oblerve, that as the means to force 

 the air through a route of fuch extent muft be very com- 

 phcated, and as a failure or accident to a part might de- 

 ftroy the whole ventilation, we conceive that much too large 

 a furface is frequently worked from two fhafts, in order to 

 avoid the expence of additional fhafts for feveral detached 

 workings of a fmaller extent. By this, the rifli of the 

 workmen is greatly increafed, to fave expence to the 

 owners of the coal. In the year 1813, fome gentlemen in 

 the north of England, impreffed by the dreadful cataf- 

 trophes which had recently taken place, very laudably eila- 

 bhflied a fociety, with a view to inquire into the caufes of 

 thefe calamities, and the pofTible means of prevention. 

 They entitled themfelves " A Society for preventing Acci- 

 dents in Coal-Mines. " Mr. John Buddie, an eminent coal- 

 viewer in Northumberland, addrefled a letter to the preli- 

 dent, which was pubhflied by the fociety in 1815. In this 

 letter he details the various methods which had been em- 

 ployed for the prevention of accidents by fire, which, he 

 fays, " confift in a mechanical apphcation of the atmo- 

 fpheric air to the removal or fweeping away of the inflam- 

 mable gas, as it is generated in the ixjorkings of collieries, or 

 as it iffues from the fiflures which the workings interfeft in 

 their progrefs." He details the various methods by which 

 this is effedled : thefe are explained by a number of figures 

 and feftions, without which they could not be rendered in- 

 telhgible to the reader. We (hall endeavour to give an idea 

 of the principle on which the various modes of ventilating 

 mines depend, by flating one of the fimpleft forms in which 

 they can aft. If two wells or {hafts were funk at a given 

 diftance, fay fifty yards from each other, and a horizontal 

 paffage were cut from the bottom of one well to the other, 

 fo foon as the communication were made, there would be a 

 tendency in the air to defcend one fliaft and afcend the 

 other, whenever the temperature of the external air varied 

 from that of the air below. The currents of air in natural 

 caverns, that are open at each extremity, proceed from the 

 fame caufe. In certain ftates of the atmofphere, (hould the 

 current not be fufficient, or (hould a quantity of impure air 



4 



be generated in the paffage, the circulation may be increafed 

 by kindling a fire at the top or at the bottom of one of the 

 wells, to rarefy the air and caufe it to afcend more rapidly. 

 Or the air may be forced down the other well, by caufing a 

 ftream of water to fall into it. Alfo by means of vanes, or 

 by an air-pump attached to a fteam-engine, the circulation 

 may be eafily increafed according to the will of th^ engi- 

 neer, and the facilities which may be prefented for carrying 

 away the water, &c. Thus little difficulty could arife in a 

 cafe of fimple ventilation of this kind ; hut if from the hori- 

 zontal paffage which runs from one (liaft to the other, we 

 make a number of paffages on each fide at right angles with 

 it, as is done in coal-mines, the current of air which palfes 

 through it will not enter thefe lateral paffages, or occafion 

 any circulation in them. In order, therefore, to make the 

 air pafs through the whole feries, another paffage muft be 

 opened, connefting the further extremities of the lateral 

 palTages with each other : the firft paffage muft then be 

 clofed, and the air which defcends condudled along the 

 lateral paffages, up one and down the other, taking a cir- 

 cuitous route through the whole, until it an-ives at the up- 

 caft (haft, which it afcends. To conduft the air in this 

 manner, a number of trap-doors and ftops are neceffary, ia 

 order to prevent the mixture of the air from the different 

 paffages, which would entirely deftroy the ventilation. See 

 Plate IV. Geology, Jig. 8. which reprefents part of the 

 workings of a coal-mine ; the fhaded part is the bed of 

 coal, in which the workings are carried along the different 

 paffages, from the pit or fhaft a, to the pit or fhaft at b. 

 The current of air is reprefented by darts and dotted lines. 

 The ftops and trap-doors, which clofe to prevent the paffage 

 of the air, and confine the currents to a particular courfe, 

 are reprefented by double lines and crofs lines, as at t t. 

 This figure reprefents the improved fyftem of ventilation, 

 by which the current of air fweeps every part of the work- 

 ings. By tracing the darts and dotted hues, it will be feen 

 that the current of air from the downcaft pit a, firft paffes- 

 along the main paffage to A, and the adjoining paffage 

 M B, to which it has accefs through lateral paffages, called 

 •walls, I, 2, 3, 4: its further progrefs in every diretlion is 

 clofed, except at 5, where it enters the paffage C, from 

 which it has accefs to the paffage D, through the openings 

 6, 7, 8, 9 : at E, the currents unite in one ftream, and enter 

 an advanced part of the workings, called the head-tuays, ven- 

 tilating the paffages F and G, being forced into them by 

 partitions called hrattces, placed at X X, round which the 

 air muft pafs in its progrefs to H. 



Where the current of air divides and fweeps along two 

 paffages at the fame time, and unites again as above- 

 defcnbed, it is called double courjing ; but where it runs 

 down one paffage and up another, as may be feen in its 

 further progrefs from H on the fouth fide, to H on the north 

 fide of the mine, it is cAlei^ Jingle crjurfng. 



The remaining part of the ventilation back to the paffage 

 K K, is in double courfes, along which it is forced by the 

 ftoppings at s, s, s, s, and the other ftoppings r, r, r, r, until 

 it afcends the upcaft fliaft at b. Under this fyftem, fays 

 Mr. Buddie, ifthejloppings, &c. be all in order, and the paf- 

 fages kept fufficiently open for the current of air to circu- 

 late freely, there can be no partial ftagnations in the work- 

 ings, — no accumulation of inflammable gas. For in the event 

 of a large difcharge of gas, from what is called a blower, 

 commencing at any place, as at M, N, P, Q, its ftream is 

 immediately carried off by the circulating current of atmo- 

 fpheric air, and fo diluted that it cannot explode, unlefs 

 indeed the difcharge of inflammable air fhould be fo copious 

 as to mix with the current up to the ^ring point, or to that 



degree 



