266 Hon. Ralph Abercroinby on the Height, 



height of any single undulation. The highest reading of the 

 series (not given here) was 28*99, the lowest 28*955, which 

 would give a difference in height of 35 feet. 



The length and velocity were measured on deck just before 

 the heights, under the following conditions : — 



Ship : length 380 feet, course E.S.E., speed 14 knots. Sea 

 running to S.E., and therefore following. 



The following are some of the best observations : — 



Time of crest, 

 running length. 



Time between 

 two crests. 



Velocity. 

 Calculated. 



Length. 

 Calculated. 



125 



19 



32 miles. 



507 



no 



15 



35 „ 



470 



9-0 





39-5 „ 





16-0 



17 



28-5 „ 



358 



This sea would have been logged as 6 or 7 on the ordinary 

 scale of 0-8. The wind was blowing a moderate to hard gale 

 from N.W. with heavy squalls, and was logged 7 on Bean- 

 fort's scale of 0-12. During some of the squalls, with thunder 

 and lightning, the force rose to 8 ; and though the ship was 

 never nearly pooped, we managed to split a topsail. I think 

 this might be taken as a fair average sea in the S. Pacific. 

 The waves were far too irregular to allow of any attempt 

 being made to determine the ratio of height to length or 

 velocity. 



July 16, 1885. Lat. 55° S., long. 105° W. 



Trough. 



Crest. 



Difference. 



Diff. of height 



eye. 



Estimated 

 height. 



29-38 



29-4025 



•0225 



6 



28-5 feet. 



•38 



•42 



•040 



6 



40 „ 



•3775 



•40 



•0225 



6 



28-5 „ 



•38 



•41 



•030 



6 



36 „ 



The readings in the trough belonging to this series are 

 remarkably uniform. 



