Tidal Investigations 9b 



Collinson point. It would appear, therefore, that the tide comes into this sea 

 from the north,_ and proceeds southward and westward along its shores. This 

 would accord with the view that the main tide of the Arctic ocean enters from 

 its opposite side, from the North Atlantic, through the wide opening between 

 Greenland and Norway. 



The Establishments obtained from these observations are not definite 

 enough to enable actual differences of time to be deduced from them, relatively 

 to sonie one of these tidal stations. The general value of XII hours for the 

 Establishment on these shores of Beaufort sea, is in good a'ccord with XI h. 38 m. 

 for Point Barrow, as formerly given in the Tide Tables of the British Admiralty; 

 but it throws doubt on the value of VI h. 03 m. which is given for Herschel island. 



At Bernard harbour, the Establishment VI h. 46 m. must be considered 

 as later than the open sea by practically the whole of this amount with the 

 deduction of the difference of longitude, which is 1 h. 46 m. relatively to 

 Demarcation point. This leaves a difference of five hours for the run of the tide 

 from the open, which seems large, when the distance from the mouth of Amundsen 

 gulf is only 360 miles. 



There is no uncertainty in the time however, as both watch and chrono- 

 meter errors have been ascertained and allowed for. (See Supplementary 

 Note.) As a term of comparison, the rate of travel of high water in the St. 

 Lawrence estuary, in the wide part unaffected by river influence, is 1 h. 31 m. 

 per 100 miles; which correepondfe fairly well with this difference, if the depths 

 are similar. 



Range of the tide. — In regard to the range of the tide, it is too slight to have 

 any direct effect upon navigation. It may be sufficient, however, to cause heavy 

 ice that is grounded to move on, under certain conditions; and any rise of tide 

 also tends to break up grounded ice. 



Procedure recommended. — With regard to general procedure in any future 

 tidal observations in the Arctic regions, it is to be strongly recommended that 

 some permanent tidal station be established for reference in the region; and 

 that it be maintained during the whole time that the explorations are in progress. 

 The observations at the various points reached by the expedition, are liable to 

 be for short periods or subject to interruption; but their value would be 

 enhanced three or four fold if they could be compared with simultaneous 

 observations at a reference station in the region. 



Without such a reference station, the time of the tide at each local point 

 where a short series of observations is obtained, has to be brought into direct 

 relation with the time of the moon's transit. At the best, it may be quite 

 uncertain whether the result represents a true average value, by which one 

 locality can be compared with another, to determine the progress of the tidal 

 undulation, or for other comparative purposes. But when the observations 

 are simultaneous with those at the reference station, differences in absolute 

 time can be determined which must be close to the true average even when the 

 series of local observations is short. The results at different localities can then 

 be compared without uncertainty, and the progress of the tide ascertained. 

 At the reference station, the Establishment can be determined correctly from 

 the long series of observations there; and the difference of time as found for any 

 local point, when applied to this well-determined Establishment, should give a 

 more trustworthy value than could be obtained indfependently. 

 "" "~ In regard to the range of the tide, there are similar advantages in comparing 

 local observations with the reference station. It can be readily seen, for example, 

 whether the local range of the tide can be taken as the true Spring range or not, 

 at the da^te of the observations. The comparison is valuable also as an indication 

 of any abnormal tides due to wind or to ice obstruction; as such tides will be 



