June 15, 1S83.] 



SCIENCE. 



533 



and also at the bottom, along a belt corre- 

 sponding nearly' with the 6o-fathom line in 

 summer. This is shown both bj- the abun- 

 dant occuiTence of the various pelagic animals, 

 gulf-weed, etc., characteristic of the Gulf 

 Stream water farther south, and bj' the tem- 

 peratures taken bj' us. The diagrams of tem- 

 perature curves in o, 10, 20, 30, and 50 fathoms, 

 all illustrate this, as well as those of the surface 

 and bottom. The recent English admiraltj' 

 charts, and others, place the inner edge of the 

 Gulf Stream, in summer, entirelj' outside the 

 slope, or 40 to 50 miles farther from the coast 

 than we have found it in this region. In 

 summer, as is well 

 known, the Gulf 

 Stream is noticed near- 

 er the coast than in 

 winter; bat this, doubt- 

 less, applies strictl_y or 

 chiefly only to the sur- 

 face water. But iu 

 summer, owing to the 

 heat of the sun, there is 

 often very little differ- 

 ence between the tem- 

 perature of the sur- 

 face water at the Gulf 

 Stream and on the in- 

 shore plateau. Our in- 

 vestigations show that 

 the warm belt, in 65 to 

 125 fathoms, is inhab- 

 ited b3' a peculiar south- 

 ern fauna that could not 

 exist there if the Gulf 

 Stream did not flow 

 along this area at the 

 bottom, both in winter 

 and summer. It is evi- 

 dent that what many of 

 these species require is 

 not a very high, but a 



nearly uniform, temperature all the year round. 

 Such an equable temperature could not exist 

 in this region, except under the direct and 

 constant influence of the Gulf^ Stream. On 

 the lower part of the slope, in 300 to 780 

 fathoms, we found numerous arctic forms of 

 life, corresponding to the lower temperature, 

 which, at 300 to 500 fathoms, is usually 41° 

 to 40° F. ; and, at 500 to 1,200 fathoms, 

 40° to 38° F. On the iu-shore plateau, which 

 is occupied bj' a branch of the cold arctic 

 current, about 30 miles wide, we found that 

 the temperature of the bottom water usuallj- 

 varied from 46° to 42° F. in August, at the 

 depths of 30 to 60 fathoms. In some instances 



it was higher than this nearer the shore, and 

 especially opposite the mouths of the bays 

 and sounds, where the tidal flow rapidly mingles 

 the warm surface water (70° to 75°) with the 

 bottom water. On the cold part of the shore- 

 plateau we also found an abundance of arctic 

 species of animals, such as are found at 

 similar and less depths north of Cape Cod 

 and in the Bay of Fundy. During the colder 

 season of the year, the temperature of the water 

 over this plateau is decidedly lower ; for cod- 

 fish, even, are taken here in large numbers in 

 winter. This plateau, especially over its shal- 

 lower portions, has, therefore, a variable cold 



Diagram 4. — Temperature cui-ves at the bottom and surface (o), and at tlie 

 intermediate deptlis of 5, 10, 20, 30, -50, and 100 fathoms. These observa- 

 tions were all made Sept. 14, 1S81. This illustrates the rise in temperature 

 between 30 and 50 fathoms from the surface. 



climate. But the deep water, below 300 fath- 

 oms, has a uniformly cold climate. It is evident 

 that the warm belt is here a comparatively 

 narrow zone along the bottom, wedged in 

 between the cold waters of the in-shore plateau 

 and the still colder waters that cover the outer 

 and deeper part of the Gulf Stream slope. 

 The actual breadth of this warm belt varies, 

 however, according to the steepness of the 

 slope, and in consequence of variations in the 

 currents. Just south of Martha's Vineyard, 

 as will be seen by map I, the slope appears 

 to be less rapid than it is either to the east- 

 ward or southward, and consequentlj' there is 

 here a broader area occupied by the warm belt. 



