43S On the Ventilation of Coal- Miries* 



derstand it ; and being persuaded that it promises many im- 

 portant benefits to miners, we were not backward to express our 

 opinion. The gentleitien who sent us tire above would, we afe 

 confident, be sorry, should any statement of theirs retard the 

 introduction of an improvenieut calculated to add to the secu- 

 rity of miners; and as we think that Mr. llyan's plan of venti- 

 lation may actually be comj)ared to tlie operation of an inverted 

 siphon, it is po.-sible, if this can be made ajjpear, that the ob- 

 jecrion wliich th.eye gentlemen have taken, to the ui-e madfe of 

 the certificate alluded to, will be thought, by themselves, to be 

 groundless . 



Let the incIined-j-ctLli -.n working ab represent a section of a 

 mine; c the down shaft' by which the atmospheric air is to de- 

 scend; and (I the up shaft -by wliich the inflammable gas is to 

 b,e discharged. When a current is once established, either by 

 the greater height of thb discharging shaft*, or by the ai>plica- 

 tlou of heat to some part' of it, the natural tendency of the de- 



* Wlioii nccess;ir_v, Mr. Jlviiii increases the hciglit of the up sliaft ly 

 uieaus of mason or brick-woik. 



scendhig 



