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2. On the Destructive Effects of the Waves of the Sea on 
the North-East Shores of Shetland. By Thomas Steven- 
son, C.E., F.B.S.E. 
The author stated, that the present communication might be re- 
garded as supplementary to the one describing the results of his 
marine dynamometer, which would be found in the 14th volume of 
the “ Transactions.” On the Bound Skerry of Whalsey, which is 
only exposed to the waves of the North Sea or German Ocean, he 
had found, on first landing in 1852, masses of rock, weighing 9J 
tons and under, heaped together by the action of the waves at the 
level of no less than 62 feet above the sea ; and others, ranging 
from 6 to 13^- tons, were found to have been quarried out of their po- 
sitions in situ , at levels of from 70 to 74 feet above the sea. Another 
block of 7 Toth tons, at the level of 20 feet above the sea, had been 
quarried out and transported to a distance of 73 feet from S.S.E. to 
N.N.W. over opposing abrupt faces as much as 7 feet in height. 
Somewhat similar evidences of the force of the sea were observed on 
the neighbouring islands, and more recently by Mr David Steven- 
son at Balta and Lambaness (in the most northern of the Shet- 
land Islands), who, in a report made at the time, attributed the 
great force of the waves in the northern regions of the German 
Ocean to their exposure and the proximity of deep water to the land. 
In addition to these causes, the author referred to the strength of 
the tides, the configuration of the German Ocean, and to the great 
general depth of the water, as the probable causes why heavier 
waves are produced in the latitude of Shetland than are found, for ex- 
ample, on the coasts of England or Holland. The author, after al- 
luding to the writings of Mr Airy and Mr Webster, referred, in par- 
ticular, to this gradually decreasing general depth in passing from 
Shetland to Holland, as a main cause of the diminished magnitude 
of the undulations. That the waves are materially smaller in the 
southern than in the northern latitudes, may be inferred from the 
low, yet safe, level at which many of our southern sea-port towns 
have been built in reference to that of high water. The author 
considered that another proof that this reduction of the waves de- 
pended on the reduction in the depth of water, might be deduced from 
the structure of the bottom. He considered that the presence of 
