2GS ANNUAL OF SCIENTIFIC DISCOVERY. 



LINES OF DEEPEST WATER AROUND THE BRITISH ISLES. 



Rev. R. Everest, F. G. S., in a paper read before the British Asso- 

 ciation, 1861, stated that by drawing on a chart a line traversing the 

 deepest soundings along the English Channel and the eastern coast 

 of England and Scotland, continuing it along the one-hundred-fath- 

 om line on the Atlantic side of Scotland and Ireland, and connecting 

 with it the line of deepest soundings along St. George's Channel, an 

 unequal-sided hexagonal figure is described around the British Isles, 

 and a pentagonal figure around Ireland. A hexagonal polygon may 

 be similarly defined around the Isle of Arran. These lines were de- 

 scribed in detail by the author, who pointed out that they limited 

 areas similar to the polygonal form that stony or earthy bodies take 

 in shrinking, either in the process of cooling or in drying. The rela- 

 tions of the one-hundred-fathom line to the promontories, the inlets, 

 and general contour of the coast, were dwelt upon; and the bearings 

 that certain lines drawn across the British Isles from the projecting 

 angles of the polygon appear to have on the strike and other condi- 

 tions of the strata were described. After some remarks on the prob- 

 able effect that shrinkage of the earth's crust must have on the ejec- 

 tion of molten rock, the author observed that, in his opinion, the 

 action of shrinking is the only one that we know of that will afford 

 any solution of the phenomena treated of in this paper, namely, long 

 lines of depression accompanied by long lines of elevation, often, as 

 in the case of the British Isles, Spain and Portugal, and elsewhere, 

 belonging to parts of huge polygons broken up into small ones, as if 

 the surface of the earth had once formed part of a basaltic causeway. 



TEMPERATURE OF THE EARTH'S CRUST. 



The following paper, detailing certain recent observations on the 

 temperature of the earth's crust, was presented to the British Asso- 

 ciation (1861) by Mr. Fairbairn, the president of the meeting: 



It is now more than ten years since a series of experiments was 

 commenced to determine the temperature at which certain substances 

 become fluid under pressure. These experiments had reference to 

 the density, point of fusion, and conducting power of the materials 

 of which the earth's cmst is composed, and were prosecuted with a 

 view to the solution ofsome questions regarding the probable thick- 

 ness of the earth's crust. Contemporaneously with these, we were 

 fortunate in being able to ascertain by direct experiments, under 1 

 very favorable circumstances, the increase of temperature in the 

 earth's crust itself. These observations were obtained by means of 

 thermometers placed in bore-holes at various depths, during the sink- 

 ing of one of the deepest mines in England, namely, the coal mine 

 belonging to F. D. Astley, Esq., at Dukinfield. The bore-holes were 

 driven to such a depth as to be unaffected by the temperature of the 

 shaft, and the thermometers were left in them for periods varying 

 from half an hour to two hours. It is very difficult to arrive at accu- 

 rate data on the subject of the increase of temperature in the earth's 

 crust. The experiments hitherto made give, unfortunately, some- 

 what conflicting results, and even in the same mine the rate of in- 



