AND OTHER WATER WAVES 89 



And at 11.50 a.m. a set of seven breakers at 

 the following intervals, viz. : 



17, 21, 16, 22, 23, 18, average 19.5 seconds. 



The general average of the periods of the five 

 sets of waves is 19.9 seconds. 



Later in the day large breakers followed one 

 another in continuous succession without the occur- 

 rence of any smooth water, and for three-quarters 

 of an hour I noted, watch in hand, a succession 

 of 139 consecutive breakers, occurring at the 

 following intervals, viz. (reading from left to 

 right): 



20, 20, IQ, 21, 19, 19, 17, 12, 20, 20, 19, 22, 



21, 21, 20, 22, 15, 18, 19, 17, 17, 20, 22, 2O, 



18, 12, 15, 19, 16, 18, 18, 22, 21, 19, 20, 18, 

 J 5(?), i5(?)i 16, 19, 20, 18, 20, 25, 16, 21, 25, 10, 



12, 22, 21, 18, 21, 19, 21, 21, 23, l8, 14, 15, 



15, 19, 19, 14, 21, 18, 19, 14, 15, 21, 18, 15, 



22, I 9 , 17, I 9 , I 3 , 20, 2 3 , 2 4 , 15, I 4 , 17, 21, 



19, 20, 28(?), 12, 24, 19, 20, 19, 19, 21, 18, 16, 

 17, 22, 26, 20, 16, 21, 22, 23, 25, 17, 15, 16, 



23, 21, 20, 15, 15, 18, 19, 26, 19, 21, 21, 18, 

 21, 19, 19, 18, 23, 18, 19, 22, 20, 20, 15, 23, 



20, l8, 2lJ, 2l, 21, 20. 



The average interval was 19 seconds, and this 

 determination is accurate to a degree not attained 

 by observations from moving ships. The recorded 

 intervals between the successive breakers probably 

 vary more than the real intervals, because if the 



