WA VES. 39 



possible, within reasonable limits, before placing reliance upon 

 them. It is evident that deductions based upon the fact of a 

 gale, with a velocity of 58 miles per hour, having produced 

 waves of only 10 feet in height, under the conditions stated, 

 would be most misleading. 



In the Bay of Peterhead, during a storm of long continuance 

 which occurred in the month of November, 1888, I noted, by 

 means of lines of sight at known levels, waves of 26 feet in 

 height (trough to crest), with occasional "lumps" considerably 

 higher. These waves were 500 feet in length, and their period 

 was from 12 to 12 \ seconds, giving a velocity of 41 feet per 

 second, or about 28 statute miles per hour. The depth of water 

 where these waves were observed was from 7 to 8 fathoms, 

 deepening seaward at the rate of about 12 fathoms per mile. 

 The fetch on the line of the gale was about 450 miles, and the 

 wind velocity was judged to be 70 miles per hour. These waves 

 crested and broke when passing the 5J-fathom line. 



It was stated, at the time of this gale, by residents in Peter- 

 head, that these waves were not nearly so high as those which 

 entered the bay during a previous storm, which occurred in the 

 year 1873. 



The maximum height of the waves (21 feet) recorded during 

 the gale described on p. 37 seems to have been limited by the 

 depth of water (23 feet), the fetch being unlimited, and the 

 wind velocity sufficient to have raised waves of greater magni- 

 tude ; whereas I think we should be right in assuming that the 

 height of the waves referred to in Peterhead feay was limited 

 mainly by the force of the gale and the distance over which it 

 acted, inasmuch as the depth of water was sufficient to have 

 admitted waves of greater height. 



Mr. Stevenson's formula, applied to this case, gives 32 feet as 

 the possible maximum height of waves, and thus supports the 

 statement, already mentioned, that waves of greater height than 

 those observed by me had, on at least one previous occasion, 

 been seen in Peterhead Bay. 



Waves running into an inlet or bay with converging sides 

 and a gradually shoaling bottom, have their energy compressed 

 into a smaller body of water, thus giving them increased height, 

 and adding to their translatory power. 



Wick Bay, on the north-east coast of Scotland, is a good 

 example of such a bay. 



