120 WAVES OF THE SEA 



in one gust and between 80 and 90 in several 

 others. The highest recorded velocity in any gust 

 was that registered by a Dines' pressure tube 

 anemometer at the Rousdon Observatory, South 

 Devon, viz., 101 statute miles per hour. The 

 results may also be expressed in this way, viz., 

 that, at a fixed station, a wind velocity of above 

 70 miles per hour has been maintained for as 

 long as 2 hours, but velocities of from 80 

 to 100 s.m.p.h. have only been maintained for 

 minutes or seconds. 



The greatest period of any short group of swells 

 which I have observed is 22.5 seconds, with a 

 speed, therefore, of 78.5 statute miles per hour. 

 M. Bertin ' says that 24 seconds (speed 84 statute 

 miles per hour) is certainly beyond all observed 

 periods in European waters. The greatest speed 

 which I have observed in a group of many swells 

 was 66.5 s.m.p.h. on December 29, 1898. The 

 greatest recorded average velocities of wind in that 

 weather were 77 and 71 s.m.p.h. on 27th and 

 28th of the same month. 



The greatest speed which I have recorded for 

 a group of a few swells is 78.5 s.m.p.h. on 

 February i, 1899. The greatest speed of wind 



1 " Experimental Study of Waves," Inst. of Naval Architects, 

 1873- 



