densities were taken at successive points on a line, each point was given a number; 

 and its position was carefully fixed by sextant angles or by log readings for 

 distance along definite courses. The latter was the usual plan when it was 

 unnecessary to stop in taking surface temperatures and surface samples of 

 water. With the ends of such lines definitely fixed, and log readings for the 

 intermediate points, all their positions could be located on the chart. Where 

 the currents were strong, the mileage as given by the log reading is corrected 

 for current, to give true distances. 



Physical Conditions 



Cold-water layer throughout the Gulf area. — The extended observations in 

 Cabot strait, the Gaspe region, and the northeastern arm of the Gulf towards 

 Belle Isle strait, agree in showing that there is a cold layer of water at a depth 

 of 40 or 50 fathoms which remains practically at the freezing point to the end of 

 the season. The warming of the surface water with the progress of the season 

 does not therefore appear to extend beyond a depth of 30 fathoms. 



In consequence of this, there are extensive bottom areas in the Gulf, running 

 in belts parallel with the shore, which must remain at the freezing point through- 

 out the year; as well as some of the banks which lie at a depth of 30 to 50 fathoms. 

 This no doubt has a bearing upon marine life. 



In the deeper channels in the Gulf area, in which the depth runs from 100 

 to 250 fathoms, the water is distinctly warmer as well as higher in density. 

 This is shown clearly in the more comprehensive tables of deep temperatures 

 and densities herein given. 



Reduced density of currents in the Gulf area, — The current along the Gasp6 

 coast in the mouth of the St. Lawrence estuary, and the out-flowing water 

 around the north end of Cape Breton island, are of relatively low density. 

 It can hardly be doubted that this low density is to be attributed to the outflow 

 of the St. Lawrence; 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. In 

 discussing the relation of the St. Lawrence to these currents, however, it is to 

 be noted that the water of low density forms only a small part of the total 

 volume which is in motion. 



The discharge of the river St. Lawrence, including its principal tributaries, 

 amounts to 240,000 cubic feet per second. This volume of fresh water will mingle 

 with sea water for which we may assume a density of 1 • 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. The surface water 

 in either the Gasp6 or Cape Breton currents is seldom lower than 1-0218 or 

 1-0217 near the shore; and the reduced density to a moderate depth may be 

 taken as 1 - 0230 on the average. 



The discharge of the St. Lawrence is sufficient to furnish a stream of water 

 reduced from the density 1-0240 to 1-0230, which would be ten miles wide 

 and 56 feet deep, moving with a speed of one knot per hour. This is a fair 

 approximation to the extent and volume of the water of lowest density in the 

 Gasp^ current; 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. 



As regards the total volume, however, the St. Lawrence river is quite 

 insignificant as compared with the outflow of the Gasp^ current. On the best 

 estimate that can be made from the data available, the volume of the Gasp6 

 current is ninety-five times the volume of the St. Lawrence river. The volume 

 of the Cape Breton current also, is probably much the same. It is thus quite 

 erroneous to speak of these currents as St. Lawrence water; as the most that* 

 the river can do is to reduce their density towards the surface by an appreciable 

 amount. 



7 



