159 



rnent was burst upwards as if by a blow from beneath : a continual 

 succession of shocks have occurred there at variable intervals up to 

 the present time. Passing on towards Brieg, the evidence of the 

 violence of the shock rapidly diminished. The valley of Zermatt 

 showed the chief disturbance ; the bridle road was continually fis- 

 sured, and in some places slipped down into the valley. At Stalden 

 there was much destruction, bat at St. Nicholas the havoc was very 

 great indeed. Higher up the traces of the shock were less and les& 

 until at Tesch, Ilanda, and Zermatt, there was no mischief done. 

 The other branch of the valley by Saas did not suffer so much. 



Drawing lines through the different places in the direction in 

 which the wave proceeded, it will be found that they converge very 

 nearly to Visp, showing that to be nearly the centre of disturbance. 

 Mr. Croker of Caius College was walking between Stalden and 

 Visp when the great shock occurred, which appeared to him to be a 

 blow from beneath like the springing of a mine under him, and he 

 observed that the path sunk several inches from the solid rock ; a 

 lofty isolated rock on the opposite side of the valley vibrated, and 

 blocks of stone came tumbling down on all sides. The quivering 

 lasted about thirty seconds. He did not observe any sound prece- 

 ding the shock, though this was heard at Visp ; but a crashing 

 sound accompanied the great shock, and a fainter sound continued 

 afterwards beyond the motion. He felt continued shocks from one 

 o'clock till four, when he proceeded towards Sion. At Zermatt the 

 same shock was felt very much less violently, and no sound preceded 

 it ; and after attaining its maximum, it ceased somewhat suddenly. 

 It was felt less strongly on the Riffelberg; and on the 27th another, 

 felt at Zermatt as strongly as before, was not felt on the little Mont 

 Cervin. 



A sound seems in general to have preceded the earthquake at 

 places near the centre of disturbance : at Visp likened to the echo 

 of an avalanche, but at a distance there was only a sound simul- 

 taneous with the shock. The sound may have arisen from the grind- 

 ing of the walls of the fissure, or whatever violent action may have 

 occurred at the origin, and the sound-waves travelling more rapidly 

 than the earthquake-wave. This is opposed to Mr. Mallet's view, 

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

 velling through any kind of stone is 3C40 feet per second, while the 

 rate of motion of the earthquake of Lisbon was 1750 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 souud be due to local 

 action. 



Chimneys and such like structures appear to have fallen away 

 from the centre of disturbance, being thrown down by the return 

 stroke of the wave ; the forward stroke having to move them only 

 lrom a state of rest, whereas the return stroke would have to over- 

 come the momentum generated by the former. 



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



