1902.] for certain Australian and Chinese Ports. 93 



agree, it seems hardly necessary to check the entering on the strips. 

 In all other respects Professor Darwin's methods were followed exactly. 



As already stated, the observations made at Brisbane and Sydney 

 were the times and heights of high and low water. They were 

 reduced by Professor Darwin's method. The observations were split 

 up into four groups, each covering about one-fourth of a year. Each 

 of these groups was separately reduced, and means of the four values 

 of k and H for each tide was taken as the final constant. These 

 separate values form a check on the work independently of the 

 systematic method of verification which was adopted in each stage of 

 the computation. In the case of the more important tides, the agree- 

 ment among the four values is very close. In the case of some of the 

 smaller tides the differences are somewhat greater, but not great 

 enough to make any serious difference in predictions based upon the 

 constants. 



The constants for the five ports are given, with others, below. The 

 small value of H (0159 foot) for M 2 at Princess Royal Harbour gave 

 rise to the suspicion that there was some error in the work. This 

 value is, however, borne out by the value of H for M 2 at Batavia 

 (Java) given in the American Tide Table for 1900. Batavia is there 

 quoted as a " Standard Port for Reference " for King George's Sound, 

 and the height there given is 0*154 foot, or only 0*005 foot different from 

 that obtained for Princess Royal Harbour. Careful examination of 

 the work showed, too, that the value given below is correct. 



Hong Kong, Swatoiv, JVhampoa, Cooktown, and Cairn's Harbour. 



The constants for these ports have been deduced at various times 

 during the past few years. Except in the case of some of the Hong 

 Kong tides, constants for these ports have not yet been published, 

 and the present opportunity is taken to include them with the 

 others. 



The observations made at Hong Kong, Swatow, and Whampoa were 

 from records by automatic gauges; those at Cooktown and Cairn's 

 Harbour were observations of times and heights of high and low 

 water. They were reduced by the same methods as the observations 

 at the other five ports. The observations for the Chinese ports were 

 kindly supplied by the Chinese Customs authorities those for Cook- 

 town and Cairn's Harbour by the Hydrographer. There seemed reason 

 to suppose that the observations at Whampoa had not been very good, 

 and the results for the tides S 6 , R, Mi, M 6 , L, /x, 2SM, J, Mf, and M m 

 seem to be so uncertain that I have thought it best to omit them from 

 the Table of Values. For a like reason the L tide is omitted from the 

 results for Cooktown and Cairn's Harbour. 



