248 



SCIEN'CE. 



[Vol. IX., No. 214 



the mean lunitidal intervals are ll^^ 33™.3 and 

 17h 45m 3 ; the mean range is 1.828 metres ; the 

 semi-mensual curves for intervals and heights give 

 the age of the tide 1.4 days, the moon tide 2.3 

 times the sun tide, and satisfy closely the equi- 

 librium formulae of Bernouilli. The diurnal in- 

 equality in height is, in comparison with the 

 whole tide, three times as small as in Smith 

 Sound ; the influence of the sun in producing it 

 is practically equal to tliat of the moon ; it van- 



non of diurnal inequality is then taken up as a 

 problem in kinematics, the diurnal inequality 

 wave is analyzed into its principal components, 

 and the sidereal period shown to have place at 

 still other stations both within and without the 

 arctic circle, and to be a rule rather than an excep- 

 tion. The results of an harmonic analysis of the first 

 year's observations will be found in the report : in 

 so far as they relate to the same matters, they con- 

 firm the results previously found and stated above. 



Z50 



2G0 



150 



100 



50 



3 



10 11 12, IS 14- 15 16 



Fig. 12. —Two groups, of ten thousand words each, from Dickens: 'Oliver Twist,' - 

 ' Christmas carol,' — . 



ishes for high water 2^ 22^1 after, for low water 

 1*108^ before, the vanishing of the moon's declina- 

 tion, and the interval of the two former events 

 appears to be independent of the solar declination. 

 A method of graphical analysis, due to the late 

 Assistant L. F. Pourtales of the U.S. coast survey, 

 brings out the fact that the diurnal inequality at 

 Fort Conger is caused by a wave that has a 

 sidereal day for its mean period ; the same thing 

 is also shown to obtain at Port Foulke and Van 

 Rensselaer harbor in Smith Sound, and at Thank 

 God harbor in Polaris Bay. The general phenome- 



A comparative study of the specific characters 

 of the Fort Conger and other arctic tides with the 

 cotidal lines, widths, and depths of the tidal 

 avenues to the Polar Ocean, with whatever other 

 tidal data from high latitudes was accessible, re- 

 sulted in certain inferences stated in the report, 

 and which may perhaps be tolerated here. The 

 weakness of the tide-producing forces near the 

 pole and a propensity to dissipate as a free wave 

 as soon as formed, in waters of even moderate 

 depth, are two causes operating to prevent the 

 generation of local tides of appreciable magni- 



