1 72 Mr. Kenwood's Facts bearing on the Theory of the Formation 



It appears to me desirable to determine the intensity of 

 springs at various depths, beneath the same surface ; and this 

 will be seen in the following columns, which denote the quan- 

 tities drawn out of Huel Hope Mine, on which there is but 

 one engine. 



TABLE I. 



I by no means intend to imply that the increase observable 

 in the preceding is entirely due to the augmented depth; for 

 the horizontal excavations are continued at the same time, and 

 I think a more extended series of observations requisite for de- 

 termining what part of the increase should be assigned to each. 

 The water is seldom drawn directly to the surface, but passes off 

 through a gallery ("the adit"), which is excavated (" driven") 

 from the nearest deep vale to the engine shaft, and is thence 

 extended to the veins, which are usually much worked at this 

 depth. The adit is in some mines forty-five fathoms from the 

 surface ; and by its great extension intercepts in its descent 

 a large portion of the rain-water which has been absorbed by 

 the earth. Of this quantity I have taken no notice. On the 

 other hand there is a loss of water in the pumps, through im- 

 perfection of buckets and other apparatus; through the en- 

 gine not making at all times its stroke of the full calculated 

 length, and by its being sometimes worked more rapidly than 

 the flow of water will supply ("going in fork"), and conse- 

 quently drawing air. 



Respecting the sum of all these defects practical men are 

 by no means agreed ; the extremes may be taken at one-fifth 

 and one-tenth of the whole. In an experiment at Huel Towanf, 

 in which I had the honour to assist Mr. Rennie, the ob- 

 served quantity was to the calculated as 83 : 92, or thereabout. 

 I think we shall not be very far wrong if we consider the 



Phil. Mag, and Annals, N.S. vol. vii. p. 424. 



rain- 



