Tidal observations in Danmarks Havn October 3rd 1906— March 2nd 1907. 431 



to become frozen in the ice. The advantage of the wire with several 

 strands was, that it was considerably stronger than a single line, 

 whereas the latter had the advantage of being more able to cut 

 through the ice. I am inclined to believe, however, that the wire 

 with several strands is the best in the long run, but it should be 

 examined frequently. 



When my participation in the sledge journeys of the first autumn 

 came to an end in November, First-lieutenant Tkolle asked me to 

 share with him the work of recording the tidal observations. 



The frequency of these will be seen from the Table, where all 

 the observations taken during the four months are recorded. The 

 time noted is the mean time of the locality and the height of the 

 water is given in centimeters. 



The daily observations are included , so as to be readily acces- 

 sible for any one who may desire to calculate the constants of the 

 tidal movement in Danmarks Havn by a different method from that 

 used by me. In my calculations I have made use of the method 

 indicated by the Rev. Dr. Whewell in his "Treatise on Tides" in 

 the "Tide tables" for 1906. 



The method given in that work has been followed throughout, 

 the time and height of water being noted on coordinate paper so 

 as to give a curve representing the course of the tidal wave ; in 

 this way the times of high and low water with the corresponding 

 heights of the water are determined. The difference between the 

 mean time for high water found in this way and the preceding mean 

 time for the culmination of the moon, upper or lower, is the lunitidal 

 interval, corresponding to the true time of the moon's transit. All 

 these intervals have been arranged in groups, which, relative to the 

 moon, extended from the first or last quarter through full or new 

 moon to the last or first quarter, or, put in another way, in groups 

 where the intervals lay in the period from the moon's transit VI 

 o'cl. through o'cl. to VI o'cl. Each group gave a curve for the 

 semimensual inequality. On calculating the mathematical means for 

 these curves — the values for every ten minutes of the moon's 

 transit being taken — we obtain a curve, which, smoothed by the 

 graphic method, is the accompanying curve III, which is therefore 

 the curve for the semimensual inequality of the establishment. 



The same method was used in calculating the curves I and II 

 and these curves thus represent respectively the semimensual ine- 

 quality of the height of the tidal wave at high water and at low 

 water. 



