302 Scientific Intelligence. 



of the secondary spark alone varies, attaining its maximum for a 

 given length of the exciter. One-fourth of the wave length of a 

 circular resonator is approximately equal to twice its diameter. 



In the case of normal reflection irom a metallic surface the 

 first node is exactly at the mirror. 



The velocity of propagation of an electric wave is the same for 

 air and conducting wires. — Archives cles Sciences Physiques et 

 JVaturelles, Troisieme periode t. xxix, April and May 1893, p. 358- 

 441. j. t. 



II. Geology and Mineralogy. 



1. The Geological Society of America. — The fifth summer 

 meeting of the Geological Society of America was held on Tues- 

 day and Wednesday (Aug. 15 and 16) in the Geological Section 

 Room of the University of Wisconsin. In the absence of the 

 President, Sir Wm. Dawson, the Vice-President, Prof. T. C. 

 Chamberlin presided. Prof. C. R. Van Hise gave an address 

 of welcome. 



Papers were read by J. W. Dawson, on the study of fossil 

 plants (read by the secretary) ; E. W. Clatpole three short 

 papers on fishes from the Cleveland shale; J. J. Stevenson, on 

 the Origin of the Pennsylvania anthracite ; C. W. Hall and 

 F. W. Sardeson, on the Ma^nesian series of the northwestern 

 states ; C. R. Van Hise, on the Succession in the Marquette Iron 

 district of Michigan ; G. F. Wright, on the Extra-moraine drift 

 in New Jersey ; A. A. Wright, on the Limits of the glaciated 

 area in New Jersey ; J. W. Spencer, on Terrestrial subsidence 

 in the southeast part of the American continent ; Warren 

 Upham, Evidence of elevation of Kames, Eskers, and Mo- 

 raines of the North American ice sheet, chiefly from its englacial 

 drift, and on the Succession of pleistocene formations in the Mis- 

 sissippi and Nelson river basins ; N. H. Darton, on the Cenozoic 

 history of Eastern Virginia and Maryland ; E. H. Williams, on 

 South Mountain glaciation ; H. F. Reid, on the Gravels of Glacier 

 Bay, Alaska ; W. P. Blake, on the Dislocations in the strata of 

 the Lead and Zinc Region of Wisconsin, and their relations ot 

 the mineral deposits, with some observations upon the origin of 

 the ores; J. H. Holmes, on the Sand Hill country and the coastal 

 plains of North Carolina ; G. H. Williams, on the Geological 

 exhibitions at the World's Fair ; (read by title) J. P. Smith, on 

 the Arkansas coal measures in their relation to the Pacific Car- 

 boniferous province. 



The following notes briefly indicate the contents of some of 

 the papers read : 



Prof. J. J. Stevenson, in his paper on the Origin of the Penn- 

 sylvania anthracite, described the geological structure of the 

 coal areas of Pennsylvania and their relation to the coal areas of 

 Maryland and the Virginias. He told of the decrease in volatile 

 combustible matter of coals along an east and west line in Penn- 

 sylvania as described many years ago. The theory of H. D. 



