12 M'Keevor's Voyage to Hudson's Bay. 



readily produced in those seas that have not free access to the 

 main body of the ocean, as also where the depth is not very 

 great. It may also be said, that owing to the currents and 

 heaving tides by M'hich they are agitated, the different por- 

 tions of water are so effectually intermixed as, in some degree, 

 to equalize the temperature. It must be observed, however, 

 that this equilibrium of temperature by no means takes place 

 with such rapidity as we should, d priori, suppose. In proof 

 of this I may adduce the well-known fact, that the tempera- 

 ture of the sea always falls in shoal-water ; hence the thermo- 

 meter has been found a very useful instrument in navigation, 

 being frequently substituted for the more tedious process of 

 sounding. It may be also observed, that fluids are very bad 

 conductors of caloric, and that, as these seas are never agi- 

 tated by very high winds, the excess of cold will readily 

 counteract the influence which the currents might otherwise 

 produce. 



The second circumstance which I have lo notice, as being 

 highly favourable for the production of ice, is a state of rest. 

 Every one who has visited these remote regions must have 

 noticed at once the remarkable stillness of the northern seas. 

 It is> in fact, as smooth and as unruffled as the most retired 

 harbour, owing, I should suppose, to the enormous pressure 

 which the ice already formed exerts on its surface.* Mr. 

 Scoresby tells us, that the ice, by its weight, can keep down 

 the most violent surges, and that its resistance is so effectual, 

 that ships sheltered by it rarely find the sea disturbed by 

 swells. This state of rest will, I conceive, favour the pro- 

 duction of ice in the same way as it does other kinds of crys- 

 tallization ; namely, by allowing the particles held in solution 

 lo arrange themselves at determinate angles. Lest, however, 

 it should be looked on as a kind of petitio principii, to argue 

 in favour of the production of ice from an effect produced by 

 ice already formed, I proceed to state the third source to 

 which I have alluded; namely, the falling of crystallized 

 snow and hail-stones. These, I conceive, may operate in two 

 ways : First, by the mechanical agitation whiph they give to 

 the surface of the ocean, thus acting in the same way as in the 

 common experiment of immersing a portion of water contained 



AH these phenomena exactly accord with the system of philosophy 

 lately promulgated by SIR RICHARD PHILLIPS, who ascribes all phenomena 

 to aggregate and atomic motion; and the frozen state of the Polar seas to 

 the diminished rotatory motion of the aggregate, as well as the diffusion of 

 the solar light, or atomic motion of light, over the oblique surface. 



EDITOR. 



