CANADIAN FISHERIES EXPEDITION, 1914-15 287 



water, into heat. In the case of the Gaspe current, the measure of these three trans- 

 formations of energy will be 955,000 horse-power. 



The divergence of the sea's surface from the level of gravity is primarily due to 

 such physical changes in the sea-water as bring about an alteration of its specific 

 gravity. The topography of the sea's surface is, however, further influenced by the 

 earth's rotation, which forces the light surface water of the currents to the right; and 

 also by the wind, which forces the water to store up. In addition, the surface of the 

 sea is subjected to various periodical perturbations, taking the form of sea waves, 

 seiches, swells, etc. In all such obliquities of the sea's surface, however, the water will 

 always be accelerated by the component which falls in the surface of the sea, if the 

 force of gravity is projected upon the same. 



One deformation of the sea's surface should be reckoned in a class apart, viz.. that 

 due to atmospheric pressure. If, for instance, the pressure above a certain area of sea 

 should fall from, say, 760 to 720 mm., then according to (15) the pressure will be corre- 

 spondingly reduced, and this, moreover, right down to the bottom of the sea; i.e., all 

 isobar surfaces within the area in question, down to the greatest depth, will be lowered 

 34 cm. The result of this will be an inflow of water from all sides to the area in ques- 

 tion, this taking place rapidly, and with imperceptible velocity, as all levels of the water 

 contribute. When this process has been completed, the siirface of the sea within the 

 area of lowered atmospheric pressure will have risen 54 cm. above its former level, this 

 height of the water exactly compensating the deficit in atmospheric pressure, so that 

 the isobars will then resume their normal course, despite the atmospheric perturbation. 

 The surface of the sea itself, however, will no longer be an isobar surface, and ceases 

 therefore, to be an indication of the distribution of pressure in the sea. This it can 

 only become through a combination of water level and atmospheric pressure. 



It is therefore a question, whether it might not be worth while, for dynamic purposes 

 to carry out this combination. The simplest method of so doing is to correct the water 

 level to a certain pressure, e.g. 1,000000'CGS, corresponding to 750-08 mm. or 29-531 

 inches Hg. at 0°. This pressure will always be found near the surface of the sea. Insert- 

 inging now in (15) gr=980-6 and i'=0- 97264, we obtain the required correction of the 

 water level for the influence of atmospheric pressure: — 



0.97264 



(p — 1000000) 



980-6 



or 



2=0-0009919 (?> — 1000000) 



Taking now as unit of pressure 1 millibar = 1,000 C.G.S., then 



2=09919 (p — 1000) (19) 



In mm. Hg. 



2=1-3224 (p — 750-08) (20) 



and in inches Hg. 



2=33-59 (p — 29-531) (21) 



Table 7, a, b, and c, gives the correction z to the water level expressed in cm. for diflFer- 

 ftnt atmospheric pressures according to formulae (19), (20), and (21), respectively. 



By applying this correction to the water levels observed, we obtain the water 

 level which determines the distribution of pressure in the sea and the movement of 

 the water. 



Finally, as regards transformation of energy in the sea, it should be borne in 

 mind that the integral expression in formula (17) gives the area of the closed curve 

 in (/lapeyron's diagram. In the case of a current >where the water flows in a Carnot 

 circular process, as for instance the Gulf Stream, the quantity of energy converted 

 from heat to motive power will thus be equal to the mass of water in circulation, multi- 

 plied by the number of solenoids. This calculation gives, for the Gulf Stream, 



