243 Intelligence and Miscellaneous Articles. 



though he gives a table in which the least rate given for sound tra- 

 veUing through anj- kind of stone is 3640 feet per second, while the 

 rate of motion of the earthquake of Lisbon was 1 750 feet. If the 

 view stated be correct, the disturbance must have been deep in the 

 earth, which would also explain the upward blow felt by Mr. Croker. 

 At greater distances the sound-wave would be expended sooner than 

 the earthquake-wave, and the accompanying sound be due to local 

 action. 



Near the centre the shock was sudden, passing away gradually. 

 At a distance it began with slight quivering, gradually attained a 

 maximum, and then suddenly ceased. Now if the disturbance oc- 

 curred along a large fissure, perhaps several miles in length, and of 

 unknown depth, the waves from different portions would reach any 

 given point in succession, and at intervals the combined effect of 

 many waves would be felt, producing a result analogous to the rolling 

 of thunder due to the varying distance of the source of sound, while 

 the sudden concussion at a nearer point is like the detonation heard 

 when the lightning is near the auditor. 



The shocks were less severe in the mountains than in the valleys. 

 As far as the wave progressing horizontally is concerned, it would, 

 on entering a mountain, at first be nearly bounded by a horizontal 

 plane continuous with that of the valley, just as light is propagated 

 in straight lines ; but there would also be a diversion of a part (ana- 

 logous to the diffraction of light at a screen) into the mountain, so 

 that where the wave passed for some distance into a range it would 

 finally be felt at the summit. It is observable that the shock on the 

 2.5th was less severe on the Riffelberg than at Zerraatt, yet it travelled 

 through the mountain and was felt at Turin. 



The period of elevation of the Alps seems about contemporaneous 

 with the older Pliocene of Sir C. Lyell. The country is broken up 

 with faults, which probably there, as elsewhere, follow the lines of 

 valleys. The valley of Visp lies in the axis of two ranges which 

 have all the appearance of a mighty valley of elevation. The shock 

 may have arisen from a shifting of the beds on this line of ancient 

 disturbance, and very probably the somewhat rectangular corner 

 between the valleys at Visp suffered the principal displacement. 

 Earthquakes in non-volcanic regions probably arise from a failure of 

 support. At the period of the elevation of the Alps, the more heated 

 lower parts of the earth's crust must have come nearer to the surface 

 than their normal position, and contractions and failure of support 

 must occur while cooling, and the comparatively recent elevation of 

 the Alps may give reason for thinking this to be still going on. 



XXX, Intelligence and Miscellaneous Articles. 



ON THE DIRECTION OF THE VIBRATIONS OF THE JETHER IN THE 



CASE OF POLARIZED LIGHT. BY M. HAIDINGER, 

 TTAIDINGER has made a communication from Stokes the oc- 

 ■*-^ casion of an interesting examination of the long-mooted ques- 

 tion whether the vibrations of the aether take place in the plane of 

 polarization or at right angles to it. The former opinion it will be 



