333 



central interruption was the usual feature in the principal anti- 

 clinals of the Ajjpalachian chain. In numerous instances, some 

 of which were cited, the anticlinal wave, where it has attained its 

 greatest magnitude, has been carved out longitudinally along the 

 axis, forming a narrow valley, many miles in length. In this 

 are seen the lowest rocks of the range, dipping in opposite direc- 

 tions so as to pass beneath the hills by which the valley is walled 

 in. These bounding hills, formed of higher strata arranged in 

 corresponding order, are but lateral remnants of what was once 

 a broad and lofty ridge, composed of successive formations con- 

 tinuously arched from side to side, but from which the violent 

 denuding actions of a former period have removed the higher 

 and central parts. The proof of this is well shown at either end 

 of the valley, where the strata of the opposite hills are seen to 

 come together, layer after layer, in the ascending order, until the 

 valley is entirely closed up, after which the anticlinal is continued 

 in a single unbroken ridge of arching strata. 



Prof. William B. Rogers called the attention of the Society to 

 the curious phenomena connected with the sonorous action of jets 

 of burning gas, which have lately been observed by Count 

 Schaffgotsch and Prof. Tyndal. 



The production of a musical sound by a small flame of hydro- 

 gen gas, burning within a tube, has long been one of the most 

 familiar of lecture-room experiments. Prof. Faraday, in one of 

 his earliest investigations, showed that this musical effect was not 

 confined to hydrogen, but could be produced with flames of 

 carbonic oxide, common illuminating gas, and several other gases 

 and vapors. He was, moreover, the first to give a philosophical 

 theory of the sound, by showing that in the conditions of the ex- 

 periment, the flame resolved itself into a series of little explo- 

 sions, which, succeeding each other at very small and equal inter- 

 vals of time, gave rise to regular and therefore musical vibrations 

 in the tube. 



In the recent experiments the further fact has been observed, 

 that the flame, both when singing and when silent in the tube, is 

 strongly acted on by external sounds, having a certain musical 

 relation to the tone of the pipe or flame. These effects, Prof. 

 Rogers illustrated by a jet of coal gas, burned in glass tubes of 



