602 



NA TURE 



[April i8, 1901 



and 150 fathoms, both in the vicinity of Ciaspe and in Cabot 

 Strait, ranges in density from i'0254 to i*026i. The density 

 of this deep water is very interesting in affording an explanation 

 for the otherwise anomalous fact that the colder water at 50 

 fathoms is found to float upon it. It also corresponds with the 

 density at similar depths, off the coast of Nova Scotia. 



Current across the Gulf area. — The general connection of the 

 Gaspe and Cape Breton currents became evident when it was 

 ascertained that the water of lower density kept to the south- 

 western side of the Gulf. The observations of the current in 

 open, and the reports from steamships, also accord with a general 

 movement of the water towards the south-east, as this is the 

 more usual direction, and the currents which are found at times 

 to run across this prevailing direction are to be attributed to the 

 influence of the tides and the wind. 



As to the route taken by the water in traversing the Gulf from 

 the Gaspe region to Cape Breton, it seems fair to conclude, 

 from the evidence furnished by the density observations, that the 

 greater proportion finds its way eastward between the Magdalen 

 Islands and Prince P'dward Island, while a certain amount may 

 also pass north of the Magdalen Islands, on the line from Bird 

 Rocks to St. Paul Island. It is probable, also, that some of 

 the water may come from Northumberland Strait, as the water 

 there is also low in its density. 



For a discussion of the probable reasons why the water of 

 lower density keeps to the south-western side of the Gult, the 

 Reports of the Tidal Survey may be referred to. 



The St. Lawrence River in relation to the outflow front the 

 Gulf. — It can hardly be doubted that the low density of the 

 water in the Gaspe Current is to be attributed to the outflow of 

 the St. Lawrence River ; and we are thus able to trace the 

 influence of this water as far as Cape Breton, where it finally 

 mingles with the water of the Ocean. The volume discharged 

 by the St. Lawrence has been measured at different seasons, 

 and with the addition of the principal tributaries along its 

 esiuary, the total volume of fresh-water discharge would 

 probably amount in all to 340,000 cubic feet per second. This 

 volume of fresh water will mingle with sea water for which we 

 may assume a density of i'0240, as this may be taken to 

 represent either the mean density of Atlantic coast water to a 

 moderate depth, or the density of the Salter water in the Gulf 

 itself. Under these conditions, the fresh water of the St. 

 Lawrence would be sufficient to furnish a stream of water 

 reduced to the lower density of i '0230 which would be twelve 

 miles wide and 68 feet deep, and moving with a speed of one 

 knot per hour. This would represent the average density of the 

 Gaspe Current, and would probably be an approximation to its 

 average speed and its volume ; and such a comparison may 

 therefore serve to illustrate the way in which the conditions 

 may be accounted for, if the data themselves were more closely 

 known. 



It is to be noted, however, that as regards volume the St! 

 Lawrence River is almost insignificant as compared with the 

 outflow of the Gaspe Current. This current, whether it flows 

 near the coast or in the middle of the passage between Gaspe 

 and Anticosti, has usually a width of about twelve miles. The 

 total depth immediately off this coast is over 100 fathoms, and 

 the depth or thickness of the current itself was ascertained from 

 measurements of the under-current taken as far down as 30 

 fathoms, at times when the surface speed varied, as usual, between 

 one and two knots. It results from these measurements that 

 we may consider the volume of this current to be represented by 

 a body of water 12 miles in width, with a mean depth of 30 

 fathoms, and moving with an average speed of o"68 knot per 

 hour, throughout this depth. 



Such a current has a volume forty- three times greater than that of 

 the St. Lawrence River. The volume of the Cape Breton Current, 

 also, is probably much the same. These outflows must therefore 

 be replaced by a return movement at the entrance to the Lower 

 St. Lawrence, somewhere in the Anticosti region ; and also by a 

 return flow from the Ocean into the Gulf area, as the discharge 

 of the St. Lawrence furnishes less than 3 per cent, of the 

 amount required in either case. 



The current which usually makes inwards around Cape Ray 

 on the east side of Cabot Strait may be sufficient to compensate 

 for the outflowing water of the Cape Breton Current ; although 

 it is also possible that the outflow from the Gulf may be partly 

 made up for by the difference of flow in the inward direction 

 through Belle Isle Strait, which in some years may be consider- 

 able in the early spring. This inflow at Cape Ray is in con- 

 tinuation of the general westward tendency of the water along 



NO. 1642, VOL. 63] 



the south coast of Newfoundland. The quiescence of the deep 

 water in Cabot Strait is also to be noted in this connection. 



It may be well to remark, however, that although the out- 

 flowing water of the Cape Breton Current is much warmer in 

 the summer season than the incoming Atlantic water, it is not so 

 at all seasons of the year. While it is probable that the total 

 result is on the side of loss of temperature to the Gulf area, it 

 would require extended observations throughout the year to 

 ascertain the amount of loss and the probable effect, in con- 

 sequence, upon climate in the surrounding regions. 



The Current in Belle Isle Strait, in relation to the Gulf area 

 as a whole. — On account of the tidal character of the current in 

 Belle Isle Strait it is clear that no great volume of water can 

 enter the Gulf of St. Lawrence from that quarter. 



During the summer season the current flows in the Strait 

 with a speed which is nearly equal in each direction ; and there 

 is only a difference in favour of inward flow to the west, which 

 on the whole does not probably amount to more than a moderate 

 percentage. From the discussion of all the evidence secured, it 

 is perhaps possible that in the early spring the preponderance of 

 inward flow may be proportionally greater than at other seasons. 

 But no reasons have been found for supposing that this water 

 passes completely round the west coast of Newfoundland and 

 finds its way out into the Atlantic through Cabot Strait, between 

 Cape North and Cape Ray, in accordance with the theory which 

 has been more or less accepted up to the present time. All the 

 indications are against this theory, as they show that any general 

 current across the extent of the Gulf must lie in an entirely 

 different direction. The reasons for this conclusion are dis- 

 cussed in the Tidal Survey Reports, in which the tidal 

 character of the flow in this Strait is described and the relations 

 of the current to the tide, the temperature of the water and the 

 drift of icebergs are fully explained. A diagram showing the 

 flow of the current in the two directions as observed is also 

 given. 



General Circulation in the Gulj. — In reviewing the move- 

 ments of the water, with a view to tracing the general circulation 

 in the Gulf, it is the principle of the balance of flow which is 

 the most evident. Wherever a current of a constant character 

 occurs, there is a corresponding return current to make up for 

 it. Thus in Cabot Strait, the outflowing water in the Cape 

 Breton Current is balanced by the inflow at Cape Ray ; the 

 north-eastward current on the west coast of Newfoundland is 

 balanced by the contrary direction of the movement on the 

 opposite shore ; and we have fairly good indications of a return 

 flow to compensate for the Gaspe Current. 



It is this balance of flow which points to the nature and : 

 direction of the circulation of water in the Gulf. If we begin to I 

 trace it from Cabot Strait, where the balance between the Gulf 1 

 and the Ocean takes place, the inflow at Cape Ray appears to 

 diffuse itself more or less widely over the central part of the 

 Gulf, but it regains its strength further north on the west coast 

 of Newfoundland, and makes a deep bend into the north-eastern 

 angle of the Gulf, and returns westward along the north shore. 

 On reaching Cape Whittle it still makes westward ; and, 

 whether as an actual set or by displacing water which comes 

 more directly from Cape Ray, it appears to work around the 

 eastern end of Anticosti, and so compensates for the outflow of 

 the Gaspe Current, from the estuary of the St. Lawrence. This 

 current, after rounding the Gaspe coast, makes south-eastward as 

 a general set or drift across the Gulf to the western side of 

 Cabot Strait ; and its waters there leave the Gulf in the outflow 

 of the Cape Breton Current. 



It also appears that the whole of the balance or compensation 

 in the Gulf currents takes place at the surface and in ordinary 

 under-currents, which do not probably extend to a greater depth 

 than 50 or 60 fathoms at the most. There is nothing, therefore, 

 to show the necessity for any appreciable movement in the deep 

 water from 60 to 80 fathoms downward, which lies in the deep 

 channels of the Gulf. Where direct observations have been . 

 obtained, this deep water appears to lie quiescent, without any 

 movement that can be detected. 



UNIVERSITY AND EDUCA TIONAL 

 INTELLIGENCE. 

 Prof. T. Hudson Beare, professor of mechanical engineer- 

 ing at University College, London, has been appointed to the 

 Chair of Engineering in the University of Edinburgh, in succes- 

 sion to the late Prof. Armstrong. 



