268 Height, Length, and Velocity of Ocean Waves. 



man only observes really high waves once or twice during a 

 lifetime ; and this view is confirmed by every sailor 1 have 

 conversed with. Taking my own measurements as repre- 

 senting only ordinary seas, I am certain that 60 feet at least 

 from trough to crest must be attained by exceptional waves. 



It may be interesting to compare the results given here 

 with those obtained by other observers. The following figures, 

 except those in the last line, are taken from Dr. Krummel's 

 Ozeanograpliie. 



Table of the Maxima Dimensions of Wav< is. 



Authority. 



Locality. 



Height, 

 iu feet. 



Velocity, 

 m.p.h. 



Length, 

 in feet. 



Period, 

 in seconds. 



Lieut. Paris 



Admiral Molter... 

 Captain Boss* ... 

 Captain Chuden.. 

 D'Urville 



Indian Ocean. 



22 ; 97 

 33-36 



980 



33-6 

 80-0 

 900 



47-5 



374 

 2703 

 1902 



984-1312 



705 



75 

 230 



10-5 







Near C. Good Hope. 

 33° S., 107° W. 







420 

 3fv0 

 230 

 460 







'Challenger' 



Abercromby 





S. Pacific. 



It is manifest, from an inspection of the above table, that 

 the discrepancies are enormous. I cannot but think that the 

 extreme lengths recorded by Admiral Molter and Captain 

 Ross must have not allowed for the interference of following 

 waves. No doubt such lengths might be observed between 

 two notable crests, but most probably there would be some 

 smaller undulation between. 1 never took the time between 

 two crests unless they manifestly belonged to a simple wave. 



The three sets of observations before noticed were taken on 

 the only three days on which at all big waves were met with. 

 They serve to show the difficulties of wave- measurement ; 

 but the greatest obstacle is the uncertainty of meeting first- 

 class specimens. If ever a wave-measuring party should be 

 organized, I think it should be arranged as follows. 



Three observers, A, B, and ( !, would be necessary. A would 

 command the party, say when the instruments were to be 

 observed, note personally the height of the deck from the 

 water, and enter all the readings on a suit able card. B would 

 have a suitable aneroid, and confine his whole attention to 

 that instrument. C would be furnished with two chrono- 

 graphs. 



When a crest touched the stern of the ship, A would give 



* Dr. Krummel's figures do not agree with those given in other places 

 for Capt. Ross's results. 



