Tidal Investigations 5b 



The observations are at the Spring tides, from May 9 to 12, 1914; taken by 

 Messrs. F. Johansen and W. S. Brooks. They are readings on a tide scale to the 

 hundredth of a foot, taken every fifteen minutes day and night continuously. 

 The Establishment obtained from the four best luni-tidal intervals, nearest to 

 full moon, is 12 h. 14 m. Relatively to the nearest transit of the moon, high water 

 occurs sixteen minutes previously; the transits being 12 h. 30 m. apart at the 

 date of these observations. The difference in the time of high water with Collinson 

 point, brought to absolute time by allowing for longitude, is thus found to be 

 49 minutes earlier at Demarcation point. 



The Spring range, from the mean of four differences between high and low 

 water, as shown in the table appended, is nearly 9 inches. The determination 

 of the Establishment is also shown in the table. 



Cape Kellett. — 'On the west side of Banks island, Beaufort sea. Approxi- 

 mate longitude of tidal station, in bay on south side of the cape, 8 h. 19 m. 

 West. — Observations were taken here in December, 1914, and January, 1915, 

 by Messrs. G. H. Wilkins and G. Thompson; and simultaneously for a few days 

 in January, by Messrs. W. J. Baur and S. Storkerson, at a point 20 miles north 

 on Banks island, which is also on the open shore of Beaufort sea. There are 

 also observations of wind and barometer, every four hours, throughout the 

 period. 



These observations were taken on a tide scale read from the top downwards 

 to the water surface; the readings being in feet and inches to the nearest quarter 

 of an inch. From December 26 to January 14 and again from January 17 to 21 

 and 27 to 30, the readings are at intervals of four hours, day and night. It is 

 unfortunate that it is not possible to deduce any result from this series of 

 observations when they represent so much labour; because the range is so 

 slight and there are only six readings of height in the twenty-four hours. For 

 two days at the Spring tides, on January 15 and 16, the observations are 

 continuous every fifteen minutes, day and night; and they become so again for 

 four complete days at the Neaps, on January 22 to 26. These continuous 

 observations were plotted on a large scale, to obtain the true tide curves. 



The observations at 20 miles north of Cape Kellett, are continuous every 

 fifteen minutes, day and night, during four days from January 22 to 26. These 

 are at the Neap tides. The best results that can be deduced for the range of 

 the tide are as follows: — 



At Cape Kellett, Spring range 0.43 foot. 



At Cape Kellett, Neap range . 40 " 



At 20 miles north. Neap range 0.41 " 



In attempting to arrive at an Establishment, the difficulties are serious, 

 because of the wide uncertainty in the time used in the observations, the small 

 number of high waters at the Spring tides, and the great irregularity in the 

 luni-tidal intervals due to the very small range of the tide. For, the time of high 

 water is derived in some cases from a tide having less than two inches of range. 

 The only note as to time error, refers apparently to the first period beginning 

 December 26. It is as follows: "Time approximately one-half hour fast on local. 

 By comparison, two hours fast on watch, January 20." In the other two 

 periods, at Cape Kellett and at 20 miles north, there is no indication as 

 to the time; and it can only be assumed that it is correct on the average, 

 although the above note is not reassuring. 



On working out the luni-tidal intervals on the basis above indicated, they 

 are found to vary from 6 to 12 hours. The variation with successive 

 transits is either from 6 to 10 hours, or from 8 to 12 hours; which must be 

 actual, as the time used would be the same in the course of any one day. This 



