174 PHYSICAL GEOLOGY. 



according to hydrostatic laws. Volcanos are an extreme case, the 

 large quantity of water in lava rendering it so light as to need for an 

 expelling force only the weight of the strata over the liquid reservoir. 



P. D. 



Everett, Prof. Seventh lleport of the Committee appointed for the 

 purpose of investigating the Hate of Increase of Underground 

 Temperature downwards in various localities of Dry Land and 

 under Water. Rep. Brit. Assoc, for 1875, pp. 14-18. Eighth 

 Eeport, pp. 156-161. 

 Records observations at the well of La Chapelle, Paris, which show 

 an increase of 1° Pahr. for from 102 to 111 ft. ; some error, from con- 

 vection, is possible. Observations at Przibram give an average rate of 

 increase of 1° Pahr. for 120 ft. ; the slow rate is considered partly due 

 to the rock being in great part quartz rock, which has high conduc- 

 tivity. At Liege the increase seems to be 1° Pahr. for every 50 feet 

 from the surface to 1600 ft. down, but at the rate of 1° to 90 ft. for 

 the lower half of that depth. 



Gives some results of observations on the temperatare of the 8t. 

 Gothard Tunnel. The temperature of the air (at first) was found to be 

 the same as that of the rock 1 metre within the Avails ; this increased 

 from ll°-5 C. at the entrance to 20°-45 C. at 1600 metres from the 

 Italian end. The springs met with when first tapped were cooler 

 than the surrounding rock ; but this difference lessened much at 2000 

 metres. Observations on the temperature of a well at Chiswick and of 

 a boring at Swinderby, Lincolnshire, are recorded, with remarks on the 

 difficulty of obtaining freedom from errors due to convection, &c. P.D. 



Favaro, Ant. Intorno ad alcuni studi del Dr. Schmidt, sui terremoti. 

 [On Dr. Schmidt's Researches on Earthquakes.] Florence. 



. Di alcuni Peuomeni che accompagnano i terremoti e dei mezzi 



atti ad attenuarne gli effetti. [Phenomena accompanying Earth- 

 quakes, &c.] Florence. 



Fisher, Rev. 0. Remarks upon Mr. MaUet's Strictures on the Mathe- 

 matical Test applied to his Theory of Volcanic Energy by Mr. 0. 

 Pisher. Phil. Mag. ser. 5, vol. i. pp. 138-142. 



Though the exact conditions of a problem may be unknown, mathe- 

 matics may be usefully applied for the limitation of the data with which 

 a particular conclusion may be consistent. The coefficients assumed 

 were those most favourable to Mr. Mallet's theory. The method used 

 was equally applicable whether there be a viscous substratum or a solid 

 nucleus. The objection of the nucleus being hotter than the heat of 

 vulcanicity is invalid, for by pressure it might attain a yet greater 

 heat. P. D. 



Fuchs, Dr. C. W. C. Bericht iiber die vulkanischen Ereignisse des 

 Jahres 1875. [Volcanic Phenomena of 1875.] Min. Mitt. Heft 

 ii. pp. 71-86. 



