274 Scientific Proceedings, Royal Dublin Society. 



5f feet above the common water-stand.' He also mentions that in 

 the Great Belt the velocity is increased in south-east storms from one 

 or two knots to five knots in the narrows of Hasselo, and that north and 

 west winds produce similar effects in the Sound ; and he adds, ' Nor 

 is it necessary to this result that the last-named winds should blow 

 home : it is enough that a gale should have swept across the North 

 Sea in that direction for several successive days.' " — [Stevenson on 

 Harbours, p. 77.) 



Major Eennell attributed the loss of " the Britannia East India 

 Ship " on the Goodwin Sands to " a current produced by the run- 

 ning off of the accumulated waters ; a violent gale from the west- 

 ward then prevailing." — [Phil. Trans., 1809, p. 400.) 



The currents on the Bosphorus are described as follows by a 

 naval correspondent of The Times : — " The main current of the 

 Bosphorus (which) has a strength varying from four to two miles 



per hour, according to the state of the weather When a strong 



■north-east wind is blowing, .... the main stream runs at a greater 

 rate even than the average of four miles previously stated. With 

 a wind from the south, a great change takes place, the course of the 

 current from the Black Sea is checked, and frequently overcome by 

 one at the surface running up." — (" Torpedo Experiments on the 

 Bosphorus," The Times, 27th December, 1882.) 



These instances may suffice to prove that violent winds have the 

 power of piling up the water before them, and of giving rise to 

 strong currents. If, however, a body of water, at any point in the 

 sea, is thus maintained at a height above the normal level, it is only 

 requisite for the restraining pressure to be suddenly removed, or for 

 the pressure to be irregular, for a wave of translation to be 

 generated by nature in a manner analogous to that adopted by 

 Mr. Russell in his experimental reservoir. This reservoir Mr. Rus- 

 sell describes as being twenty feet long, having an additional length 

 of 7'3 inches reserved to form a generating chamber. " By filling 

 the generating reservoir with water to a higher level than the ex- 

 perimental reservoir, while the sluice was closed, on raising it the 

 water descended, producing a wave of which the volume was known." 

 — [Trans. Brit. Assoc, vol. vi., p. 435.) 



In nature the accumulated water could be released either by a 

 sudden decrease in the force of the wind or by a change in its 

 direction. Both these conditions are present in storms when the 



