.s/A' WILLIA^f SIEMi:.\S, /.A',v 385 



In the ilisctission of the Paper 

 "ON THE CHALK WATER SYSTEM," by JOSEPH LUCAK, 



DR. Si KM K.VS said * an observation had fallen from Mr. Baldwin 

 Latham which, he thought, ought not to pass unchallenged that 

 the water flowing from deep wells was warmer than that flowing 

 from shallow wells, and that the increase in temperature in it 

 might be attributed to the greater friction of the water through 

 the Chalk Formation. Mr. Latham had correctly given the co- 

 efficient of increase, 1 for every 772 feet of water percolating 

 downwards ; but Mr. Latham had apparently not considered the 

 fact that this difference of level did not include the depth of the 

 water in the well, but only the depth from the surface where the 

 rain fell to the level of the water in the well, because the depth of 

 water in the well balanced so much of the hydrostatic pressure as 

 would urge the water through the chalk, and therefore did not add 

 to the accelerated force, or the force to be developed into heat by 

 friction. It was therefore necessary to consider what was the dif- 

 ference of level between the water in the well, and the level where 

 the rain fell and sank down into the ground ; and there could be 

 no doubt that that amount of hydrostatic pressure was lost, and 

 therefore converted into heat. But would that heaHippear as tem- 

 perature in the water ? He doubted it very much, because before 

 the well was pumped the chalk was filled with water, and that 

 water was in static equilibrium. It was only when the well was 

 worked that the water would flow and friction be generated. That 

 amount of friction would not only heat the water, but it had to 

 heat the stratum of chalk before it could be sensible to a thermo- 

 meter, and considering the enormous mass of material which would 

 thus have to be heated by a comparatively small amount of water, 

 Dr. Siemens thought the idea of heat being derived from mechanical 

 friction in the chalk must be dismissed. Mr. Latham's observa- 

 tions seemed almost to imply that he attributed heat-engendering 

 power to the horizontal distance traversed by the water ; and it 



* Excerpt Minutes of Proceedings of the Institution of Civil Engineers, Vol. 

 XLVII. Session 1876-77, pp. 134-135. 



VOL. II. C C 



