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probable that the conducting power of the different strata increases 

 considerably with the depth, the materials becoming more compact 

 under augmented pressure. It is not improbable also that pressure 

 may raise the temperature of fluidity. In either case the solid crust 

 of the globe would be thicker than it had been supposed to be on 

 the assumed data. With the view of throwing light upon this 

 question so interesting to all geologists, ]\Ir. Hopkins undertook, 

 with the assistance of Mr. Fairbairn and ]\Ir. Joule, to subject 

 various substances under different temperatures to enormous pres- 

 sure. Considerable time was required, even with ^Ir. Fairbairn's 

 unlimited mechanical means, to construct the necessary apparatus ; 

 however, recently it has been completed, and in the few substances 

 examined it has been fouud that the temperature of fusion has 

 increased with the pressure : in the case of wax, by a pressure of 

 13,000 pounds to the square inch, the fusing-point was raised 30°. 

 Whatever may be the influence of these experiments as affecting the 

 great questions of Terrestrial Physics, we may predict with certainty 

 that data will be obtained most valuable in philosophical research. 



Mr. Joule, I find, has been actively engaged, in conjunction with 

 Professor Thomson, in his experiments on the thermal effects of 

 fluids in motion, and has determined with considerable accuracy, 

 operating on a great scale, the depression of temperature when com- 

 pressed air escapes into the atmosphere through a porous plug. The 

 laws of the phenomena as to the temperature and pressure of the 

 confined gas, will also soon be determined. » 



Carbonic acid gas has been found to give a depression of four and 

 a half times as great as atmospheric air, while it passes through 

 the porous plug with greater facilit}" than atmospheric air ; equal 

 volumes requiring pressures of 1 and I' 05 respectively in order to 

 be transmitted in equal times. Certain heating effects of air rushing 

 through a single orifice have been observed, which will probably 

 lead to a further development of the mechanical theory of the tem- 

 perature of elastic fluids in rapid motion. 



The examination of the sedimentary deposits in the Nile vaUey, 

 mentioned at the last Anniversary, is still going on. Mr. Horner 

 states, that by the munificent aid of His Highness Abbas Pacha, the 

 Viceroy of Egypt, a series of operations have been carried on at 

 Heliopolis, and at another station thirteen miles above Cairo, which 

 have led to interesting results. A pit has been sunk to the depth of 

 24 feet below the pedestal of the colossal statue of Ramses the 

 Second, who reigned, according to the chronology of Bunsen, about 

 1400 years before Christ, and borings have been continued by which 

 cylinders of soil have been extracted at an additional depth of 4S 

 feet. A series of thirty- two pits has been sunk across the valley in 

 a line between the Libyan and Arabian deserts, occupying a line of 

 about five miles, passing through the site of the statue alluded to ; 

 and it is proposed to sink a similar line of pits next year about twenty 

 miles lower down the river, passing through the site of the obelisk 

 of Heliopolis. Above sixty persons M"ere employed in the operations 

 at Memphis. The plan, as proposed by Mr. Horner, was, through the 



