CONTENTS. 



On the means by which it has been alleged, that whole 

 towns, and even great ranges of country, may be pre- 

 served from the injurious eifects of lightning, . 278 

 On the effects of great fires burning in the open air, 279 

 On the noise of cannon as a means of dissipating thunder 

 storms, ....... 281 



Is it useful or dangerous to ring great bells during a thun- 

 der storm ? . . . . . . 286 



IV. Reply to Professor Bischof s Objections to the Che- 

 mical Theory of Volcanos. By Charles Dau- 

 BENY, M.D., F.R.S., Professor of Chemistry and 

 of Botany, Oxford. Communicated by the Author, 291 



V. Upon the alleged influence wiiich the Roughness and 

 the Polish of surfaces exercise upon the Emissive 

 power of Bodies, in reference to the Experiments 

 of Professor Sir John Leslie. By M. Melloni, 299 

 VI. Account of an Intermitting Brine Spring discharging 

 Carbonic Acid Gas, near Kissingen, in Bavaria. 

 By Professor Forbes. Communicated by the 

 Author, . . . 306 



History of the Spring, . . ^ 309 



Phenomenon of Intermittence, . . 313 



Temperature of the Spring, . . 317 



Products of the Spring, . . .322 



VII. On a Method of obtaining the greatest possible de- 

 gree of Exactitude from the data of a Survey. 

 By Mr Edward Sang, F.R.S.E, M.S.A., Civil- 

 Engineer and Machine -maker, Edinburgh. Com- 

 municated by the Society of Arts, . 327 



VIII. A Series of Facts and Observations respecting the 

 Natural Causes of Arborescent or Dendritic Fi- 

 gures in the two divisions of Animal and Vege- 

 table Structures, and in Mineral Formations. By 

 Sir Anthony Carlisle, F.R.S. Communicated 

 by the Author, . . . 344 



IX. On the Natural History of Volcanos and Earth- 

 quakes. By Dr Gustav Bischof, Professor of 

 Chemistry in the University of Bonn. Communi- 

 cated by the Author. (Concluded from p. 81.) 347 



X. On the Vibration of Suspension Bridges and other 

 Structures ; and the means of preventing Injury 



