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SECTION IX. 



PERMANENT REFERENCE MARKS ON THE ISLAND OF FUNAFUTI. 



By G. H. Halligan. • 



In order that permanent marks should be available for future reference, both as 

 to level and to the contour marks of high and low water on the ocean and lagoon 

 sides of the main island of Funafuti, some iron pipes were let into the coral rock in 

 the positions shown. (See Plate 19.) These pipes were 4 inches outside diameter 

 and from 3^ to 4 feet in length. They are sunk to a depth of from 2 to 2|- feet 

 into the solid rock of the reef platform, are firmly secured with Portland cement 

 and filled with the same material, and each mark stands 15 inches above the 

 surface, so that they can be seen from a considerable distance. On my arrival at 

 the atoll I found that Mr. Finckh had already sunk copper plugs in the positions 

 shown on the plan, but as these stood only about 1 inch above the surface of the 

 coral, they were diflficult to find, though perhaps they were less liable to injury on 

 a storm-swept coast than the marks I have now left. In order to indicate the 

 positions of these plugs more clearly to future visitors, we decided to sink three of 

 the cement-filled pipes alongside them, and as the pipes would be exposed to the 

 full fury of the storms which break off the masses of coral from the outer edge of 

 the reef and hiirl them shorewards to form the Hurricane Bank, it was thought 

 desirable to place another mark at about high water, the exact position of which is 

 shown on the plan referred to. The top of this mark (A on the plan) is 7 '60 feet 

 above the zero of the tide gauge used on the survey of the atoll, made by Captain 

 MosTYN Field, R.N., of H.M.S. " Penguin," in 1896, and is 5'98 feet below the bench 

 mark on the south-west corner of the Mission Church. According to information 

 kindly supplied by Admiral Sir W. J. L. Whaeton, Hydrographer to the Admiralty, 

 the mean tide level, as deduced from the two months' observations made during 

 this survey, is 3 "3 8 feet above the zero of the gauge. The mark A may then be 

 taken to be 4*22 feet above this mean tide level and approximately the same height 

 above mean sea level. For measurements of any considerable movements in elevation 

 or subsidence this mark may be of value, but, of course, a series of observations 

 extending over a much longer time would be required before mean sea-level could 

 be determined with sufficient accuracy to admit of minute measurements. The two 

 pipes forming the permanent marks on the lagoon side of the islet are in the vicinity 

 of the northern end of the " Sandy Beach," shown on the Admiralty chart, about 



