Canadian Arctic Expedition, 1913-1918. 



TIDAL INVESTIGATIONS. 



Rosults Deducible from the Tidal Observations 



By W. Bell Dawson, D.Sc, M.Inst.C.E., F.R.S.C, 

 Superintendent of the Survey of Tides and Currents, Ottawa, Canada. 



During the course of this expedition, under the leadership of Mr. Vilhjalmur 

 Stefansson, observations of the tide were obtained in the years 1914 and 1915 

 at seven points ; situated along the open coast of the continent, eastward from 

 Alaska to the head of Amundsen gulf, and north of this gulf on Banks island 

 and in Prince of Wales strait. These may be classed together as being in the 

 region of Beaufort sea. In the year 1916, tidal observations were obtained 

 farther north, at three points which were on the open shore of the Arctic ocean 

 or in straits, in the vicinity of Ellef Ringnes land. These localities are shown 

 on the accompanying map. 



The expedition was supplied with an outfit of instruments by the Tidal 

 and Current Survey, comprising a current meter with a set of accessories, a 

 large registering tide gauge with two interchangeable clock cylinders, and 

 another registering gauge of a more portable type. These gauges were furnished 

 with spare fittings and all the accessories necessary for their operation. 



The difl&culty in using these gauges arose chiefly from the clock-work being 

 stopped because of the hardening of the clock oil with the cold. This type of 

 gauge is successfully used throughout the winter in the regular work of the 

 Tidal Survey, under the severest weather conditions, with outside temperatures 

 as low as 40 degrees below zero. But they require to be properly installed, with 

 heating to maintain a temperature above the freezing point. On this Arctic 

 expedition, the gauges were sheltered in snow houses; and it appears to be 

 possible to keep such houses at a temperature of 40° to 50° Fahrenheit by lamp 

 heat, without thawing the interior. The tide well, cut through the ice within 

 the house, could thus also be kept from freezing up. 



Another difficulty arose from the very small range of the tide in these 

 regions. The range on the open shores of Beaufort sea was usually less than 

 one foot, and seldom as much as one and one-half feet; and the greatest range 

 met with, at the head of Amundsen gulf, and in the extreme north, occasionally 

 exceeded two feet. With so small a range, the tide curves on the recording gauge, 

 or when plotted from scale readings, were very flat; and when the height was 

 read directly from a scale, the readings required to be at very frequent 

 intervals, to be of service. 



TIDAL DATA DEDUCIBLE. 



On an expedition of this character, it might not be practicable to establish 

 permanent headquarters where a tidal station could be maintained in continuous 

 operation for purposes of comparison. But if some inhabited locality such as 

 Herschel island, had been equipped as a reference station, all the tidal observa- 

 tions in the region could have been referred to it; and a much more satisfactory 

 reduction of the observations would result. This plan of having a reference 

 station for each region, is the uniform practice in the investigations of the Tidal 

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