On the Ventilation of Coal-Mines. 43d 



spending atmosphere, owing to its greater gravity, will be, to 

 take the lowest station, descending along the bottom of the 

 path or working fiom c to a, while at the same time the car- 

 buretted hydrogen bv its levity being sent to the roof will pro- 

 ceed onward to I till the space fioui I to d be filled with it, 

 when it v.ill ascend the shaft d — the heavier aeriform fluid filling 

 and occupying the lower station. 



Let ABCD represent a ground plan ', c f, g h, i k, I m, n o, in- 

 clined workings ; and pcj, r s, t ti, v w. xy, the cross workings. 

 Let the dov.-n shaft and the up shaft be supposed placed in the 

 most favourable circnnistanccs — say, th.e former at n and the lat- 

 ter at A, and the mine will ventilate itself. But owing to some 

 cause, we shall not inijuire what, these shafts shall be supposed 

 placed in less favourable circuisistances — sayj the down shaft at 

 c and the up shaft at d. How is this mine to be ventilated ? 

 By forcing tiie descending atmospheric air to go down one in- 

 clined working and up the nest, then down the third and up 

 the fourth, &C. traversing tiie whole workings (the cross work- 

 ings being stopped up where necessary) till, after travelling 25 or 

 30 miles, the atmospheric air blended with and diluting the in- 

 flammable air, both be conducted to and discharged by the up 

 shaft ? No, says Mr. Ryan : take advantage of the law of gra- 

 vity, the lieavier air will take the bottom, the lighter the roof; 

 ^nd by proper management tlie lighter may be diiected to the 

 up shaft in an unceasing cnrvcnt, with a velocity proportioned 

 to the quantity !ibcratea from the v,-orkings, the prcssiu'e of the 

 air in the do^vn shaft, and the artificial means (the application 

 of heat. Sec.) which in any case may be resorted to. IIow does 

 he effect this ? Let a gallery ABCD be excavated all round 

 the workings. Let the cross workings iinmediatelv on each side 

 of the inclined course which descends from k to d be left uncut, 

 or, what is the same thing, stop them up so effectually tliat no 

 air of any kind can reach tl;e up shaft </, but what must come 

 from the upper part DC of the air gallery ABCD. In this case 

 thongli the gas will have to descend from k to d, bei'jre it can 

 reacii the shaft d; the current being once established it will 

 meet with no imjjedinjent, the ligl'.ter carburettcd hydrogen being 

 pressed u'pward by the heavier atmos);heric air, descending the 

 other shaft, aiul occuj)ying the lower station. Lv't the course of 

 the inflanniiable gas be ever so tortuous, like water discharged 

 downward by a siplion (however crooked) it will find its place 

 of discharge upward at the orifice of the longer limb [shaft]. 



Such we conceive to bq a brief outline of Mr. Rvau's system. 

 In such a short article wc cannot pretend to have done it per- 

 fect justice ; mvich less can we enter into details respecting the 

 vents and openings^ which in some cases may be rendered in- 

 £ e 4 dispensable. 



