AND OTHER WATER WAVES 77 



Abercromby ' relate to waves observed in the 

 South Pacific Ocean on a voyage between New 

 Zealand and Cape Horn on S.S. Tongariro in 1885. 

 On July 1 6th the ship was in S. Lat. 55, W. Long. 

 105, in a hard gale from SW. The waves were 

 the largest seen on the voyage. For the measure- 

 ment of their height he used a 4j-inch aneroid 

 barometer with a very open scale divided to 

 .01 inch. He found (on the assumption that a 

 difference in .001 inch in the aneroid reading was 

 equivalent ,to a change of i foot in level) that 

 in passing from trough to crest the greatest lift 

 experienced by the aneroid in the cabin was 

 40 feet. This was a solitary instance. The next 

 greatest was 30 feet. Now, on a previous day, he 

 had found by measurement with a piece of string 

 that, when the wave -crest passed the cabin, the 

 porthole was 6 feet nearer the water than it was 

 at the trough of the wave. Assuming the same 

 difference to hold during the day of heavier sea, he 

 adds 6 feet to the lift of 40 feet in order to obtain 

 the total height of the greatest wave, which he 

 therefore considers to have been 46 feet. He 

 reckons the liability to error of the aneroid read- 

 ing at 2 to 2.5 feet, and that of the measurement 



1 Phil. Mag., April, 1888 (vol. xxv., 5th series), " Observa- 

 tions on the Height, Length, and Velocity of Ocean Waves." 



