35

C—la

In a similar way the other eight sections are analysed, giving the following results: — R £ Section » 2 «, Feet. 1 .. 38 0 .. .. .. 3-8375 2436 2 .. 76 38 .. .. .. 37969 2656 3 .. 114 76 .. .. .. 3-5607 2407 4 .. 152 114 .. .. .. 8-8707 2200 5 ..Hid 152 .. .. .. 3-7977 23-91 (i . . 228 190 . . .. .. 3-8220 22-74 7 .. 266 228 .. .. .. 3-6290 2374 8 .. 304 266 .. .. 3-8116 20-92 9 .. 342 804 .. .. .. 3-8277 2519 9)33-9517 9) 212-49 8-7727 23-61 Compare 3 - 7828 2551 from abacus Difference 0-0101 1-90 It will thus be seen thai the results of analysis by this method agree closely with those obtained from the abacus. No corrections have been applied for the influence of other tides on the Ah tide in the above results, while the results from the abacus are corrected ones. The corrections due to the other tides depend on the corresponding values of II f in equation (7). and the. following table shows the relative importance of these products:— R. SRs. Tide. Feet. M 2 .. .. 3-783 -t- 753-6 v 2 .. .. 0-234 + 19-is S., .. .. 0-583 12-71 N", .. .. 0-79] + 6-11

TIDE-GAUGE. A new tide-gauge (see illustration) has been designed and constructed in Wellington, and as it possesses some novel features a description of it may be of interest. It is based on the Wellington Harbour Board tide-gauge designed by Mr. \V. Ferguson. M.A., M.lnst.C.E., and described in " Transactions of the New Zealand Institute," Vol. xli (1908), page 107. The gang,- consists essentially of the pencil actuated by the clock, and the paper moved by the tide. The pencil-carriage Cis in train with the driving-weight \V of the clock and moves 6 in. per day, so that the gauge will run for oxer a week without attention. Tinpaper is attached to the flat table AB and consists of a block of paper cut to fit the table. The blockremains on the table and a sheet is taken off once a week. The table oscillates with the tide, and the method of attaching it to the spindle of the lloat-\\ heel is shown clearly in the illustration. It is found convenient to have the record-paper on a flat table instead of on a cylinder, as in the more usual forms. The gauge is constantly referred to by the harbour engineer during dredging operations, and measurements can now be made without taking the record-paper off the gauge. The ratio for heights is '~ so that I ft. of movement of the float is shown as I in. OB the record, and this gives a convenient scale for measurements. The gauge has been running lor some months h\ tin- side of Ihe Harbour Board gauge and is performing satisfactorily. It is proposed to instal the gauge at Suva to obtain sufficient records there for a harmonic analysis of the observations to be carried out.

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