14 



The agreement between the values of the constants in successive months is as close as can be expected 

 and may be regarded as quite satisfactory. 



The zero readings (mean sea-level) for the successive months were found to be 4 37, 3-61, 3-90, 3-00 

 feet respectively. In regard to the last value, it should be remembered that this belongs to the period 

 following the breaking of the wire. It would seem certain that there was an irregular change of zero due 

 to shifting of the ship's position in the ice, consumption of coal, &c., and that from these values there is 

 nothing to be inferred. 



As a check on the analysis the initial values for the various components obtained were calculated for 

 h., June 1, 1903, and, with the aid of the Indian tide-predicting machine in the charge of the National 

 Physical Laboratory, a curve was run off for the two months June and July. The observed heights for 

 the five days beginning h., July 3, 1903 (astronomical time), have been plotted for comparison with the 

 curve given by the machine. The two curves are shown in the diagram on p. 15 opposite. The curve 

 obtained from the observations, where distinguishable from the machine curve, is indicated by a broken 

 line. Crosses mark the observed points. The mean sea-level for the " observation " curve is that given 

 by the mean of the five days' heights. The agreement over these five days is sufficiently close. It may 

 be noted that where the two curves separate they could in each case be brought much nearer to 

 coincidence by a change of- zero, as distinct from the addition of another harmonic term, and that such 

 change of zero, as already pointed out, is to be expected. 



The differences between the observed heights and the machine heights were also obtained for every 

 hour on the following days: June 4, June 19, July 1, July 11, and July 24. The zero in each case is 

 arbitrary, but if the analysis were accurate and complete the difference should be constant. The actual 

 differences on these five days, however, would appear to indicate a variation having an approximate 

 amplitude of 5 inches, and possibly of approximately diurnal period. This is not apparent in the 

 comparison curves, and further investigation would be necessary before any conclusion could be arrived at 

 in regard to it. 



With reference to the wind records, there is nothing calling for any special comment in connection with 

 the tides. It is clear that the winds have not sensibly impaired the value of the observations, which 

 appear to have been taken with great care, and have been found quite satisfactory for purpose of analysis. 



F. J. SELBY, M.A., 1 Tidal Assistants at the National 



J. DE GRAAFF HUNTER, B.A., J Physical Laboratory. 



December 20, 1906. 



