260 Experiments to determine the [Oct. 



engine-shaft; because the resistance is made a cause much less 

 powerful than the effect it is supposed to produce. 



Two or three probable conjectures may be offered to account for 

 the sudden appearance of the water in the upper level; but no per- 

 son, except one that is intimately acquainted with the peculiarities 

 of that part of the mine in question, can give the real cause. If 

 the water be a part of that which before entered the lower level, 

 we may suppose that at the time the engine ceased to work, the 

 channels through which it entered the lower level were too small 

 for the then quantity of water in the feeds ; so that they could not 

 force themselves into it, without first completely filling the chan- 

 nels to within two or three fathoms of the higher level, and 

 thereby acting with the power equal to that of a column of water 

 of the same height and area. With this altitude we will suppose 

 the feeds could make their way into the lowef level, as they were 

 collected into the channels. But when the engine stopped, and 

 the water had filled the lower level, they would have to overcome 

 the resistance which the water in this level opposed to them in their 

 progress through it : to overcome this resistance a certain increase 

 of altitude was necessary; but before this was acquired, the feeds 

 reached the upper level, and a part of them, if not the whole, 

 passed along this level to the shaft. It is possible that the appear- 

 ance of the water in the upper level may be owing to some tem- 

 porary stoppage, either in the lower level, between where the feeds 

 enter this level and the engine-shaft, or in the channels. If either 

 of the two last instances be correct, the appearance of the water so 

 high in the mine will be of short duration. It is also possible that 

 either the stoppage may be permanent, or the feed of water in the 

 upper level may not have communication with those in the lower 

 level : in either case the water will continue to run along the 

 former level. But of these conjectures I think the first is the most 

 probable. 



I am, Sir, with much respect, your humble servant, 



J. B. LoNGMIRE. 



Kendal, in Westmoreland, 

 July 31, 1814. 



Article VI. 



Exper'nnents to determine the Constituents of Azote. 

 By John Miers, Esq. 



(Concluded from p . 193.) 



Symbolic Representation of the intire Changes that have taken place 

 in the Gases now under Consideration. 



Water, H O, and sulphureted hydrogen, S If, contaminated 

 with an uncertain portion of hydrogen, H, as is always the case 



