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IV. — Account of Experiments upon the Force of the Waves of the Atlantic and 

 German Oceans. By Thomas Stevenson, Civil-Engineer, Edinburgli. Com- 

 municated by David Stevenson, Esq. 



In forming designs of marine works, tlie engineer has always a difficulty in 

 estimating the force of the waves with which he has to contend. The information 

 on such a matter, which is derived from local informants, who, although intelli- 

 . gent in the departments of trade which they follow, are, nevertheless, more or less 

 prejudiced from being constantly on the spot, is not satisfactory ; and it has, there- 

 fore, often occurred to me that it would be most desirable if the engineer could 

 be enabled, to some extent at least, to disregard the prejudiced statements of others, 

 and the vague impressions left by them on his own mind, and really to ascertain, 

 by direct experiment, M'hat force, expressed in pounds per square foot, the sea 

 actually exerts upon the shores where his buildings are proposed to be erected. 



Notwithstanding the want of all direct experiments* on this subject, and the 

 somewhat unpromising nature of such an enquiry, I was, nevertheless, induced to 

 attempt the construction of an instrument to effect the desired end ; and after 

 several fruitless devices had been put to the test, I at length succeeded in forming 

 one whose indications I hope to be able to shew are trustworthy. Before con- 

 sidering the results obtained, however, I shaU explain the construction of this 

 simple self-registering instrument. 



The letters DEED represent a cast-iron cylinder, which is firmly bolted at the 

 projecting flanges G to the rock 

 where the experiments are 

 wanted. This cylinder has a 

 flange at D D. L L is a door, 

 which is opened when the obser- 

 vation is to be read off". A A 

 is of iron, and forms a circular 

 plate or disc, on which the sea 

 impinges. Fastened to the disc 

 are four guide-rods BBBB. 

 These rods pass through a circu- 

 lar plate C C (which is screwed 

 down to the flange D D), and also through holes in the bottom E F. Within the 



* Sir S. Brown has infleed stated, that at Brighton he found the impetus of the waves during 

 heavy gales was " equal to 80 lb. to a foot upon a cylindrical column of 12 inches diameter." The 

 hydrostatical pressure of a wave only \\ foot high is equal to 80 lb. upon a square foot. 



