48 Mr. R. Edmonds on Earthquakes and 



improbable. Assuming (as the passage quoted allows) that 

 there is no " submarine volcano/' nor any dislocation or frac- 

 ture of the submarine ground, a violent shock proceeding up- 

 wards vertically from a horizontal portion of the basin of the sea 

 would pass through the sea as through a solid, without displa- 

 cing any water until it reached the surface, which would be then 

 dashed up. If a ship were floating on the spot, that part of the 

 surface immediately under her would transmit the shock to the 

 ship, and loose articles on her deck would be jerked up to heights 

 proportioned to the violence of the shock. Thus on board a 

 ship 40 leagues west of St. Vincent, the men were thrown "a 

 foot and a half perpendicularly up from the deck "*. 



If the submarine ground, instead of being horizontal, were an 

 inclined plane forming the steep side of a mountain, a shock 

 proceeding vertically from the interior of the earth would, on 

 leaving this inclined plane, pass through the sea in a direction 

 perpendicular to the plane ; and when it reached the surface of 

 the sea, that surface would be dashed up in the same direction. 

 If the shock were moving westward, a ship receiving it while 

 sailing eastward would be stopped as suddenly as if she had 

 struck on a rock. Instances of this are also on record. 



Now let us imagine some shore descending, at an angle of 45°, 

 to the depth of a furlong or two under the sea. If this received' 

 a vertical shock, the sea resting thereon would transmit the shock 

 to the surface of the water, which surface would be then dashed 

 seaward. If the shock were not repeated, the water driven sea- 

 ward would instantly now back towards the shore to regain its 

 level. But if countless shocks or vibrations followed in rapid 

 succession (as is commonly the case in earthquakes; for a "shock" 

 is generally a rapid succession of vibrations like those produced 

 by letting out a ship's cable f), another dashing seaward of the 

 surface would take place, followed by countless others, until the 

 water thus driven on would be raised into a considerable heap ; 

 so that w r hen the vibrations or shock ceased, it would flow back 

 towards the shore and rise perhaps above its previous level. This 



* Lyell's 'Geology/ vol. ii. p. 241, 3rd edit. 



t In reading descriptions of earthquakes felt under ground, above ground, 

 and at sea, I have been struck with the three classes of comparisons by 

 which the noises accompanying them have been represented. Persons 

 under ground have compared the noise to that of " the breaking of a 

 'studdle' (wooden platform), and the ' deads' (rubbish) being set a run- 

 ning," and to "the falling of a ' kibble' (bucket) down the shaft." Those 

 above ground likened it to " the rolling of stones," and " the rushing of 

 waggons down a road." Sailors at sea compare it to "the letting out of 

 the cable." All these comparisons, varying according to the situation of 

 the observer, show that the " shock " consists of a rapid succession of vi- 

 brations. 



