WAVES OF THE ATLANTIC AND GERMAN OCEANS. 25 



In 1842 several observations were made on the waves of the Irish Sea at 

 the island of Little Ross, lying off the Bay of Kirkcudbright. Since April 1843 till 

 now, continued observations have been made on the Atlantic at the Skerryvore 

 and neighbouring rocks, lying off the island of Tyree, Argyllshire. And in 1844 a 

 series of similar observations was begun on the German Ocean at the Bell Rock. 

 It will be seen, that in selecting these localities a varied exposure has been em- 

 braced, comprising the comparatively sheltered Irish Sea, the more exposed eastern 

 shore of Scotland, and the wild rocks of Skerryvore, which are open to the 

 full fury of the Atlantic, the far distant shores of North America being the nearest 

 land on the west. 



Referring for more full information to the tables of experiments which are given 

 at the end of this paper, it will be sufl&cient in this place to state generally the 

 following, as the results obtained. 



In the Atlantic Ocean, according to the observations made at the Skeri-yvore 

 rocks, the average of results for five of the summer months during the years 1843 

 and 1844, is Gil lb. per square foot. The average results for six of the winter 

 months (1843 and 1844), is 2086 lb. per square foot, or thrice as great as in the 

 summer months. 



The Greatest result yet obtained at Skerryvore was during the heavy westerly 

 gale of 29th March 1845, when a pressure of 6083 lb. per square foot was regis- 

 tered. The next highest is 5323 lb. 



In the German Ocean, according to the obsei-vations made at the Bell Rock, 

 the greatest result yet obtained is 3013 lb. per square foot. 



It thus appears, that the greatest effect of the sea, which has been observed, 

 is that of the Atlantic at Skerryvore, which is nearly equal to three tons per 

 square foot. 



These experiments, amounting to 267 in number,* and on the Atlantic alone 

 extending over 23 months continuously, are not intended to prove any thing far- 

 ther than the simple fact, that the sea has been known to exert a force equivalent 

 to a pressure of three tons per square foot, however much more. Now, when we 

 consider that the hydrostatic pressure due to a wave of 20 feet high, is no more 

 than about half a ton on a square foot, we see how much of their force the 

 waves owe to their velocity. There can be no doubt, however, that results 

 higher than this will be obtained. Were a train of observations made at various 

 points of the coast, the result would not only be highly useful in practice, as 

 they would by reference to existing marine works shew what sizes of stones and 

 proportions of piers were able to resist seas of a given force ; but they would 

 form an interesting collection of information with regard to the relative forces 

 of the waves in our contracted bays and estuaries, as compared with those ob- 



* It was not thought necessary to give all the observations in the table appended to this paper. 

 VOL. XVI. PART I, G 



