74 Scientific Intelligence. 



roid, with a coatiug of paraffin or beeswax, and then allowing 

 it to slowly contract. Folds, fractures, and elevations are ob- 

 tained having interesting relations to those which have been 

 observed in the earth's structure and features. In other experi- 

 ments, on subjecting a ball of caoutchouc to pressure, the effects 

 of pressure normal to the surface were obtained. 



The new experiments on the effect of vapors, are described in 

 papers in the Comptes Rendus for 1890 and 1891 (the last in 

 August, 1891), and also in part in a communication to the Geo- 

 logical Society of France of February, 1891. Two of the subjects 

 illustrated are (1) the pressure of exploding materials, as gun- 

 cotton, and (2) the production of more or less cylindrical perfora- 

 tions, tunnel-like, along fissures by vapors suddenly developed, a 

 form of fracture called by Daubree a diatreme. The origin of 

 the conduits of volcanoes and explosive eruptions, and of the 

 diamantiferous pipes of South Africa is thus explained by the 

 author ; and also the extrusion of the trachyte of trachytic domes, 

 the lofty throws of volanic cinders and rocks and other related 

 volcanic products, and the forms of the ejected broken blocks and 

 lapilli. To these projected rocks or fragments, the name ecphy- 

 seme is proposed, from the Greek for something bloicn out. The 

 explosive agent recognized in the natural operations is, in general, 

 the vapor of water suddenly generated. Other effects obtained 

 are the erosion and fusion of granite, and other substances; the 

 production of molecular transfer or flow, resembling that of plas- 

 ticity, and a resoldering or remoulding of a crushed rock. The 

 great heights of the more remarkable volcanic mountains are 

 reviewed and their groupings. On the occurrence of similar 

 heights in the mountains of a group and their origin through 

 diatremes, Prof. Daubree says : " it is as if each corresponded 

 to a maximum of pressure proceeding from the same infra-granitic 

 reservoir, or from similar reservoirs of whose pressure it gives a 

 measure, like the tube of a manometer in the open air. 



The paper published in the Bulletin of the Geological Society 

 of France contains figures illustrating the methods of experiment 

 and the various results, and reviews their general applications to 

 volcanic and other geological phenomena. Prof. Daubree ob- 

 serves that in contrast with the forms of fractures of the earth's 

 crust which are linear, parallel, and are produced by horizontal 

 pressure attending contraction, diatremes or " topic dislocations " 

 are the effect of action concentrated on a single point, of vertical 

 projection by a gaseous material acting with great velocity under 

 heavy pressure " une sorte de coup de canon, dont 1'ame serait 

 une diatreme qui viserait le zenith." These memoirs of Prof. Dau- 

 bree will be read Avith great profit by geologists. 



3. A classification of Mountain Ranges according to their 

 Structure, Origin and Age / by Waeeen Upham ( Appalachia, 

 vi, April, 1891). — Mr. Upham divides mountain elevations into 

 (1) folded, (2) arched, (3) domed, (4) tilted, (5) erupted, and (6) 

 eroded. The first division is exemplified in the Appalachian 



