OBSERVATIONS IN CANADIAN WATERS. 97 



It seems hardly uecessaiy to remark, that it must often be a matter of vital conse- 

 quence that the master of a ship should be able to ascertain at any time the " rate and set " 

 of a current which is acting on his ship. In hazy or foggy weather, or in dark nights, 

 when in the neighborhood of land, all the j)recautions that the utmost skill may dictate, 

 and the utmost care employ, may be thrown away, if the mass of water in which his 

 ship is lloating, is itself travelling bodily in a direction unknown to him, carrying his 

 ship to destruction. Now in general at any place, the tidal current shifts its direction 

 four times a day according to the eld) or How of the tide, from permanent causes, leaving 

 out of account, for the present, atmospheric changes. It is, therefore, obvious that, in 

 average weather, it ought to be possible, if proper investigations be made, to obtain such 

 information for each locality (for of course, the conformation of the land, and other local 

 circumstances must atl'ect thi^ current.) as would be a guide to navigators. 



Ac<-ordingly we iind in the P.ritish and Irish tide-tables, no less than forty pages 

 devoted to a description of the tidal currents off the coast of the British Isles, under the 

 headings ''South Coast of England," "East Coast of Scotland and England," "West Coast 

 of Scotland,"' "Tidal streams among the Orkneys, in the Irish Channel, in the English 

 Channel, in the North Sea." For more accuracy, the J'lnglish Channel and North Sea, are 

 divided in the tables into what are called "compartments " because, as is said with refer- 

 ence to the English Channel, "the courses of the stream in the mixed tides are so change- 

 able, that a very ditter(>nt stream will be found running at a place l)ut little removed from 

 another in the same portion of the Channel." 



The investigations from which the recorded resvrlts have l)eeii obtained have been com- 

 paratively recent, and some of the rules to which they have led are of admirable simplicity. 

 In a paper contained in the Philosophical Transactions of the Royal Society of Lon- 

 don for 1848, Admiral Beechey gave an account of his survey of the currents in the 

 Irish Channel ; from which he deduced the remarkable fact that, notwithstanding the 

 variety of times of high water throughout the channel, the turn of the stream, over 

 all that part which may be called the fair navigable portion of the channel, is nearly 

 simultaneous, and that this happens to correspond nearly with the times of high and of 

 low water on th(>. shore at the entrance of Liverpool and of Morecambe Bay. Thus the 

 time when the stream turns at any place in the channel can be calculated simply from 

 knowing the times of high and of low water at either of these places. 



In the Philosophical Transactions for 1851, will be found another i)aper by the 

 same author, in which he shows, from a subsequent survey of the English Channel 

 and North Sea, that a similar rule holds there, — the turn of the stream depending on the 

 times of high and low water at Dover. In passing it may be remarked, that this 

 shows the special importance of accurate tide-gauge observations at Dover and Liver- 

 pool. The papers in the Philosophical Transactions are accompanied by charts, showing 

 the course and rate of the tidal streams throughout the whole extent of the channels. 



Now, compared with what is given in these tide-tables for the British and Irish 

 coasts, the information for the Gulf of St. Lawrence, the coasts of Nova Scotia and of 

 Labrador, and for Canadian waters generally, is excessively meagre. A comparison of 

 dates will show, in a striking manner, that this might naturally be expected. Admiral 

 Beechey's investigations were reported in 1848 and 1851. But the survey of the Gulf 

 on which the Charts and Pilot Books in ordinary use are founded, was made by 



bee. III., 1885. lo. 



