MR MILNE ON A REMARKABLE OSCILLATION OF THE SEA. 633 



nomenon, I consider, was connected with the storm of which I have just traced 

 the extent and progress ; and to this conclusion I am led, by the following con- 

 siderations : 



(1.) In the first place, the phenomenon has, as already shewn, been generally 

 accompanied by violent storms, or other proofs of atmospheric disturbance. 



(2.) The oscillation on the 5th July began in the English Channel, and did 

 not, till some hours after, manifest itself on the east coast of Scotland. So, also, 

 the storm began in the south, and moved northward, the parts both of the English 

 and the Scotch coasts most aifected by it, being those where the oscillation was 

 observed. 



(3.) In so far as it is possible to judge of the part of the ocean in which 

 the oscillation was generated, that part coincides with the direction from which 

 the storm came. 



It has been seen, that the oscillation began at Plymouth about 11 A.M., and 

 at Penzance about half an hour later. l It probably originated, therefore, in the 

 English Channel, considerably to the SSE. of Mountsbay. 



Now, it is stated that, early in the morning, at Mountsbay, there was heard 

 a distant thunder-storm in that direction, and that, before 3 P.M., a sudden 

 storm of wind came on from the south, and, almost simultaneously, a heavy sea, 

 so as to endanger even large fishing-boats, and that the sudden cessation of the 

 wind and sea was as remarkable as their sudden rise. 



It is very manifest, that this was the same storm of which the progress has 

 above been traced ; and it is probable, therefore, that they both came from the 

 same part of the ocean. 



(4.) The circumstance that the oscillation of the sea on the Cornish and 

 Devonshire coasts preceded the arrival of the storm by some hours, so far from 

 being an objection to the view above suggested, is rather a confirmation of it ; as 

 it is well known, from the researches of Mr SCOTT RUSSELL, that a wave, when 

 generated by a moving force, will acquire a velocity greater than that of the force 

 producing it, if the depth of water be sufficient. I have elsewhere shewn, that 

 the waves produced by the Lisbon earthquakes came to the English and Irish 

 coasts, with a velocity of from 120 to 160 miles an hour. It is therefore probable, 

 that if a wave were generated by the storm in question, it would move forward 

 with about double the rapidity of the storm itself, which, I have shewn, travelled 

 at a rate of only 70 or 80 miles an hour. 



Whilst the considerations now submitted appear to me sufficient to connect 

 together the storm and the oscillation, I am aware that something else is awant- 

 ing to prove the relationship of cause and effect. In what way, then, is it pos- 



1 There is some doubt as to this. In the Athenscum of 1843, p. 849, it is stated that the tide 

 had ebbed about half an hour when the oscillation occurred. Now, it was high water in Mountsbay at 

 9 b 54' A.M., and, according to this account, the oscillation occurred about 10 11 24'. 



VOL. XV. PART IV. 8 H 



