i895. NOTES AND COMMENTS. 155 



his discourse by explaining the meaning of " fault " and other equally 

 simple terms. The contrast between this and the Geological 

 Congress held in London, 1888, was very striking. The explanation 

 is, no doubt, partly due to the fact that in England physical geography 

 is studied rather as a branch of geology than of geography, and the 

 geologists were not tempted to abandon their field work and remain in 

 London. At the Geological Congress the honorary president was 

 Professor Huxley, whereas the office was filled on the present 

 occasion by one king and four princes. The vice-presidents at the 

 one were twenty-two of the leading geologists of the day, representing 

 the twenty countries who sent delegates to the Congress. The first 

 two pages of the list of honorary vice-presidents of the Geographical 

 Congress looks like the record of the attendance at a levee. This 

 probably gave English geologists, who are a democratic race, the 

 impression that the Congress would be social rather than scientific, 

 and thus they did not interrupt the season's field work and return to 

 London to welcome their foreign colleagues. When they know the 

 names of the men who came, and the character of the contributions 

 laid before the meeting, we cannot but feel that many of them will 

 deeply regret their absence.^ 



Deep-seated Water. 



To bore for water at the celebrated falls of TroUhattan seems at 

 first to be a carrying of coals to Newcastle. That it can hardly be so 

 is shown by the fact that not only one bore-hole, but two or three, 

 have been or are being sunk through the hard gneiss rocks at great 

 expense. The history of these deep sinkings is one of much interest, 

 both practical and scientific. 



Twenty-seven years ago, in a paper on the geology of Spitz- 

 bergen, Nordenskiold published some observations on the influence of 

 cracks in masses of igneous rock. His ideas, subsequently developed 

 and now put to a successful test, are, in a few simple words, some- 

 what as follows. In all large masses of igneous rock — or in such 

 tracts of gneiss as extend over many hundred miles of Sweden — 

 there are cracks and joints of varying extent and direction. Even if 

 such cracks were at first quite insignificant they would slowly but 

 inevitably be increased in size by a small but perpetually active set 

 of forces. When, under the influence of cold, the rock contracts, the 

 cracks are widened ; thus a vertical crack (cc.) becomes filled with 

 water, sand, or mud. When, under the influence of heat, the rock 

 expands, the crack, which would naturally be closed, remains wedged 

 open by its new contents. Thus a pressure, minute but irresistible, 

 is brought to bear on the rock-mass and forces it in a horizontal 

 direction. And the process is repeated and repeated through the 

 ages, as the cracks again widen and become filled with more water, 



1 We hope to publish an article on the work of the Congress next month. 



M 2 



