166 Scientific Intelligence. 



ing the existence of stationary light Avaves, analogous to the 

 sound waves shown in Kundt's experiment. The author has also 

 endeavored by his method to settle the question of the direction 

 of the vibration of light with respect to the plane of polarization, 

 and believes that his experiments show that these vibrations take 

 place perpendicular to this plane. He also shows that the chemi- 

 cally active vibrations and the electrical vibrations are in the 

 same plane. In other words, the chemical action of the light rays 

 is joined to the vibrations of electrical force and not to those of 

 magnetic force. — Ann. der Physik und Chemie, No. 6, 1890, pp. 

 203-243. j. t. 



7. Electrical Oscillations in air. — Recent experiments in the 

 Jefferson Physical Laboratory of Harvard University, conducted 

 by John Tbotvbeidge and W. C. Sabixe, show that the medium 

 of the dielectric exerts a marked effect upon electrical surgings 

 or oscillations. The spark from a large air condenser was 

 analyzed by a rapidly revolving mirror and the oscillations 

 photographed. A marked periodicity in the time of the electrical 

 waves was discovered when the air condenser was employed. 

 When a glass condenser was substituted for the air condenser the 

 periodicity became less marked. The, glass evidently could not 

 recover from the initial strain in time to interfere with the recur- 

 ring electrical oscillations. In the case of air, however, the partial 

 recovery from each electrical wave served to modify the time of 

 the latter. The w T ork of the authors shows that for rapid charges 

 and discharges of an air condenser the factor expressing the 

 capacity is a periodic function, the value of which depends upon 

 the state of strain of the air. — Proceedings of the American 

 Academy of Arts and Sciences, May 18, 1 890, pp. 109-1 23. j. t. 



II. Geology and Mineralogy. 



1. The American Committee of the International Congress 

 of Geologists. — In the February number of the American Geolo- 

 gist (vol. v, No. 2), p. 125, is a report of a meeting of the 

 "American Committee of the International Congress of Geolo- 

 gists" held in New York Dec. 26, 1889. What is meant by the 

 name is the Standing Committee of the American Association on 

 the International Congress. As there is now an American Com- 

 mittee of the International Congress which is known in the 

 French language of the Congress as the American " Comite 

 d'Organisation," and is recognized as such by the London Bureau 

 of the Congress, and as it is necessary for this committee to act 

 in its official capacity as the American Committee of the Con- 

 gress in organizing the American Session, I beg to call attention 

 to the misuse of the name by the Committee of the American 

 Association. 



There are three committees in America which have to do with 

 the International Congress of Geologists, and as several gentle- 

 men are members of all three of the committees, care is neces- 

 sary not to confuse them in their official capacities. 



