5t) 



KNOWLEDGE. 



[March 1, 1901. 



simply according to the " state of the sea." Only the 

 mean values are here reprodiicod from the original 

 Table III. 

 Observations by Lieut. Paris. 



Region. 



• This columu canuot be calculated from the two preceding columns. 



table. In Table III. the same observations are 

 grouped geographically. The first question -which 

 occurs to one is -whether another cruise -would give 

 similar -waves in the same areas. Fortunately -we 

 can compare the heights of the waves -with those 

 observed (about 1837 a.d.) on the voyage of the 

 Astrolabe, of -which a summary was published in 1866 

 (Compter rendus ties fiances de /'Acad, den sciences. 

 Vol. LXII.), by M. Coupvent des Bois, -who -was himself 

 a member of the expedition. The method of observing 

 the height of the -waves -was the same as that adopted 

 Ijy Paris. The velocity of the -wind is also given but does 

 not seem to be comparable with Paris' numbers. The 

 verbal description of the state of the -weather is, however, 

 some guide in this case. (Table IV.) The average 

 heighti of the waves in the trade winds of the Atlantic 



Table IV. 



Observations on the Astrolabe 



It will be noticed that vclocitie." for strong winds arc quite uut 

 of accord with Paris' determinations given in Table I. 



and Indian Oceans is very nearly the same in the two 

 cases. The lai-gest waves were met with on both voyages 

 in the southern Indian Ocean. The results for the 

 Pacific Ocean differ much ; I doubt, however, if the area 

 included by Paris under "Pacific west," is the same 

 as the western part of the " Oi-ean Pacifique eijuatorial " 

 of Des Bois, so that the difference of results may have 

 but little jjhysical significance. 



Des Bois' method of grouping the waves in longi- 



tudinal strips of 30° is convenient. In the equatorial 

 Pacific (0° to 30° lat.) the mean force of wind and the 

 mean height of the waves diminished from east to west, 

 being near the Asiatic coast only -| to ^ of the height 

 near the American coast. In the equatorial Indian 

 Ocean the winds and waves were highest in the middle. 

 In the equatorial Atlantic the waves were highest on 

 the western side, although the winds were strongest in 

 the east. In the centre there was a medium height of 

 wave combined with the lowest force of wind. In the 

 latitudes 60°-66O S. we note the strongest winds with 

 relatively low waves. I suspect that the relatively small 

 height of wave is due to floating ice. which, as Norden- 

 skiold has pointed out, has a marked effect in smoothing 

 the sea. The total number of observations was about 

 7200. I infer from the text that the height of the waves 

 was not actually measured at each observation, but that 

 suificieut measurements were taken to satisfy the person 

 resjjonsiblc for the work as to the height of wave which 

 corresponded with the entry " state of the sea." This state 

 of the sea was noted six times daily, each such note 

 constituting, I suppose, one " observation," from which 

 the average heights given in Table V. were afterwards 



Table V. 



Observations on the Astrolabe. 



Compare last column with column 4 of Table II. 



Velocity of Wind. 

 Feet per Second, 



I*^iliiaiorial Pacific 

 Ocean 

 (00—30° lat.) 



Kquatoi'ial Indian 



Ocean 



(0"— 30" lat.) 



Equatorial 



Atlantic Ocean 



(0°— 30 lat.) 



30°— 50' 



50"— 60° S. 



50=— 60° S. 



60° -04 S. 

 60°— 66" S. 



75-l](,w 

 110 140 „ 

 140-170 „ 

 170w.1G0e: 

 1 60-1 30 E 

 130 100,, 

 120-90 „ 

 90-60,, 

 60- 30 „ 

 lOK.-llw. 

 l(i\v.-30 ,, 

 30-50 „ 

 .111 longi- 

 tudes 

 Meridieu [ 

 d'Amerique 

 Meridien 

 NouTelle- I 

 HoUande ! 

 Meridien 

 d'Amerique 

 Meridien 

 Nouvellc- 

 HoUande 



1.5-42 "-I 



13-45 



19-14 



av. 15-75 



11-11 



15 09 "1 



I 

 1903 i- ay. 17.00 



24-94 



23-95 Uv.24 45 



Height of Waves 

 in Feet. 



11-48'^ 

 6 56 I 



^■''H-iv .5-69 



3-94 r 



3-94 I 

 3-28J 

 6 89 ■) 

 11-81 ^iv. 8-42 

 6-56; 

 4-20 ) 



6-56 [. ar. 6-12 

 7-55 ) 



7-22 



6-89^^ 

 I 

 14-44 l-av. 10-67 



6 891 



6 89 I- av. 6-89 



1 



J 



calculated. This connection between " state of the sea " 

 and height- of wave, found by measurement, is given in 

 Table A' J. Tliis should be com])ared with Paris' 

 Table 111. 



The following observations of waves were made by 

 the Hon. Ralph Abercromby* on board the s.s. Taii- 

 gariro, in various parts of the South Pacific, 

 between New Zealand and Cape Horn, in 1885. The 

 observations of height were made with the aid of a 

 4A inch aneroid, with a very open scale divided to 0.01 of 

 an inch. Altitudes were calculated on the assumption 

 that 0.001 inch difference of pressure corresponds to 



* Observations on the Height, Length, and A'elocit.v of Ocean 

 Waves, read before the Pliysical Society, February 25th, 1888, 

 published in tlie Phitosophical Magazine, April, 1S88 (Vol. XXV., 

 5th Series). 



