Septembeb 23, 1910] 



SCIENCE 



413 



graphic plates reproduced in the papers re- 

 ferred to. It may be further pointed out that 

 in minute spark gaps, such as are found use- 

 ful in X-ray circuits, there is an oscillation 

 ■which appears to promote the discharge. 

 There is strong evidence which is being 

 further examined, that these oscillations are 

 due to an alternation of conduction and con- 

 vection discharge across the gap. This in- 

 volves a surging to and fro of the carriers, 

 from one terminal to the other. 



Faraday observed that there was no ap- 

 preciable " electric wind " when a brush dis- 

 charge becomes somewhat disruptive in char- 

 acter. He appears to have left Franklin's 

 suggestion of a one-fluid theory wholly out of 

 consideration. The mingling of convection 

 and conduction discharges is sufiicient to ac- 

 count for the phenomenon which Faraday 

 observed. The brush discharge between two 

 terminals becomes disruptive when the nega- 

 tive terminal is moved into contact with the 

 end of the positive column. If the gap is 

 made still shorter, until the distance between 

 the knobs is equal to the length of the Fara- 

 day dark space, the critical spark length has 

 been reached. 



In the papers referred to, it was suggested 

 that the stria in the Geissler tube were in the 

 nature of vibrations in an organ pipe. This 

 explanation simply involves the assumption 

 that a wave consists of a dark space and an 

 adjoining luminous segment. These are re- 

 spectively regions of convection and conduc- 

 tion. They are Faraday dark spaces and 

 positive columns. In them the carriers are 

 moving in opposite directions. The nodal 

 planes where pressure is at a maximum and at 

 a minimum alternately both in space and in 

 time, lie between the dark and luminous seg- 

 ments of the waves. At the instant when the 

 pressure is at a maximum and a minimum at. 

 adjoining nodes, the convection transfer is 

 zero. The conduction transfer will at that in- 

 stant be at a maximum and a minimum at 

 consecutive nodes. These conditions may ex- 

 plain the displacement of the striations which 

 have long ago been observed. 



Francis E. Nipher 



TEE INTERNATIONAL GEOLOGICAL CON- 

 GRESS AT STOCEBOLM 



The success of any great gathering of geol- 

 ogists may fairly be gauged by the men 

 brought together, by the interest of the prob- 

 lems illustrated on the excursions, by the 

 comfort and the pleasures of the entertain- 

 ment, and lastly, it would seem, by the 

 papers, conferences and discussions. Meas- 

 ured by all of these standards, the eleventh 

 International Geological Congress, which was 

 held in Stockholm during the month of Sep- 

 tember, will take a high rank among interna- 

 tional scientific gatherings. The number of 

 geologists in attendance was in excess of seven 

 hundred, and the distinction of the names 

 represented was noteworthy. From Germany 

 came such men as Beck, Bergeat, Beyschlag, 

 Credner, Groth, Keilback, v. Koenen, Penck, 

 Eothpletz, Eudolph, Salomon, Sapper, Stein- 

 mann, Wahnschaffe and Walther; from Aus- 

 tria-Hungary, Briickner, Diener, v. Cholnoky 

 and Tietze; from Canada, Adanas, Coleman 

 and Miller; from Denmark, Stunstrup and 

 Ussing; from Egypt, Hume; from France, 

 Barrels, Prince Roland Bonaparte, Haug, 

 Kilian, Lory, de Margerie and Termier; from 

 Great Britain, Cole, Garwood, Gregory, Home, 

 Oldliam, Peach, SoUas, Strahan and Teall; 

 from Italy, Baldacci, Capellini de Stefani and 

 Mattirolo ; from Japan, Inouye ; from Mexico, 

 Aguilera and Ordonez; from Norway, Brog- 

 ger, Eeusch and Vogt; from Russia, Andrus- 

 sow, Loewinson-Lessing and Tschernysehew; 

 from Finland, Frosterns, Ramsay and Seder- 

 holm; from Sweden, Gunnar Anderssen, J. G. 

 Anderssen, Backstrom, de Geer, Hamberg, 

 Sven Hedin, Hogbom, Holmquist, Lindbahm, 

 Moberg, Nathorst, Nordenskiold and Sernan- 

 der; from Switzerland, Baltzer, Brunhes, 

 Heim, Lugeon and Schmidt (Carl). The roU 

 from the United States included Bascom 

 (Miss), Becker, Bryant, Cross, Day (A. L.), 

 Emmons, Fenneman, Grabau, Hague, Hobbs, 

 Irving, Kemp, Lindgren, Newland, Reid, Rich- 

 ards, Smith (G. O.), Spencer (J. W.), Tarr, 

 Van Hise, Winchell (H. V.) and Wolff. 



The Swedish people enjoy a wide interna- 



