On the Ventilation of Coal-Mines. 437 



I do not mean to say, there are no cases where the theory of 

 Laplace can be applied with advantage: but they are very rare; 

 and it ought only to be resorted to when there is not the means 

 of obtaining correct information. 



W, 



LXXXVIII. On the Ventilation of Coal Mines. 



Newcastle, Oct. 5, 1816. 

 E whose names are undersigned, being persons who com- 

 posed the meeting held at the Assembly-rooms, Newcastle, on 

 the 9th of September 1815, observing that Mr, Ryan has af- 

 fixed the resolution of that meeting, with our signatures, to his 

 *' Letter to the late Secretary of the Society of Arts, on his Method 

 of ventilating Coal-mines," feel ourselves called upon to declare, 

 that no part of that method was then explained to us, but simply 

 an application of the inverted siphon to the clearing away of 

 collections of carburetted hydrogen gas, which may have accu- 

 mulated in cavities in the higher levels of a coal-mine; which 

 he illustrated by the common experiment of a bended glass tube 

 immersed in two fluids of different densities. 



In consequence, however, of this general explanation of Mr. 

 "Ry&n's principle, — the particular application of which, at the same 

 time, he expressly declined communicating, — we thought it right 

 to give our testimony of general approbation of it, " as consistent 

 with the principles of philosophy;" and, in consequence of his 

 assurances of its successful application in certain coal-mines in 

 Staffordshire, " recommended the propriety of its adoption to 

 be taken into consideration by persons interested in the coal- 

 mines." 



On the merit or demerit of the plan now pointed out by Mr. 

 Ryan, we do not feel ourselves called to give an opinion. Our 

 only object is to state, that no communication of it was made 

 to us at the meeting above alluded to. 



R. W. Grey, John Hodgson. 



J. H. BiGGE. Christ. Bknson. 



WiLUAM Turner. Wm. Clark. 



Nat. John Winch. Wm. Armstrong. 



John Carr. Rob. Wm. Brandling. 



The preceding document would have appeared in the last 

 number of the Philosophical Magazine, had we not been disap- 

 pointed of the wood-cut which now accompanies a few remarks, 

 which we think the subject calls for. We examined with some 

 care Mr. Ryan's plan for ventilating mines : we think we un- 

 E e 3 dcrstand 



