104 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



that they mark the outlines of a former and now retreating 

 glacial covering, which lias protected these remains of 'still 

 earlier upheavals from the weathering and degradation which 

 has befallen any such raised and broken surfaces in warmer 

 regions. 



In another essay Dr. Peschel opposes the theory of the ex- 

 istence of mountains and valleys in the sea bed correspond- 

 ing to the inequalities of this character observed on the land, 

 and maintains that every island is either the unsubmerged 

 height of a sinking portion of the continent nearest to which 

 it lies, identifiable as a former portion of the main land by its 

 geological structure, its fauna, or its flora, or else that it has 

 been independently raised by volcanic force or by the labors 

 of the coral insect. 



In another chapter Dr. Peschel opposes the idea that the 

 mountain ranges have been formed by outbursts of incandes- 

 cent lava ; but finds in chemistry, the power needed for the 

 result, especially in the combinations of carbonic acid and 

 silica, which produce a chemical change resulting in the re- 

 duction in specific gravh^, and a considerable increase in the 

 volume of the mass. 



From a careful study of the subject, Dr. Peschel thinks he 

 can show that since the tertiary period the continents have 

 tended to add to their extent northward and westward, and 

 to lose by submergence to the south and east, the gain in the 

 one case being exactly counterbalanced by the loss in the 

 other, the proportions of land and water remaining the same. 

 He also considers it to be a popular fallacy that the destruc- 

 tion of forests reduces the rain-fall on the land, and thinks it 

 useless to attempt planting in those countries in which woods 

 have not flourished naturally in historic times. This idea, 

 however, Mr. Johnston very sensibly opposes as being contra- 

 ry to well-established facts. 13 A, June 1,1871,286. 



EXPEDITION OF THE HASSLER. 



The daily papers of the past summer have kept their read- 

 ers advised of the preparation of the great exploring expedi- 

 tion upon which Professor Agassiz has been expecting to en- 

 gage during the voyage of the Coast Survey steamer Hass- 

 ler from Boston to San Francisco, by way of the Straits of 

 Magellan. The expedition was originally to start as early as 





