200 Influence of the Polar Ice on other Climates. 



something, though not much) converts the water into ice. But 

 the conversion itself is accompanied with circumstances that tend 

 to temper and lessen this reduction of temperature ; or, in other 

 words, to warm the neighbourhood; namely, tlie impossibility of 

 water (even when reduced below the freezing point) becoming ice, 

 without further giving out a large ])ortiou of caloric. 



If the bisin of the lake was hlled with sand instead of water, 

 the cold experienced in the neighbourhood from the operation of 

 the grand causes above alluded to, would be severer than it is 

 when water occupies the place; that is, the presence of water 

 tempers the cold. It is true indeed, tliat afterwards, if l)y some 

 other grand process of nature the air of the place should bo 

 warmed, and any of the ice should melt, that action of melting 

 being accompanied by a specific absorption and locking up of ca- 

 loric, the temperature of the air in the neighbourhood, and iu 

 the places to which that air is carried, is, at that time, made 

 lower than it would be, if, instead of ice being present, sand or 

 gtone at the same temperature occupied its place. But even if 

 the whole of the ice should melt, the loss in temperature 7ioWf is 

 no more than the gain before. 



In general, one may suppose that the presence of a large body 

 of water tends to equalize the temperature of a place; cooling 

 the air in the warm weather, and warming it in the cold. But 

 however this may be, it never can he fairly said that the accumu-^ 

 lation of ice tends, on the whole, to lower temperature. And if 

 it be true, that ice has been accumulating for centuries back 

 about Greenland, that accumulation must have given warmth to. 

 Europe (or at least to the world) during those centuries. And 

 if this ice be now melting, that process of melting is one occasion 

 of diminished heat. And when the ice shall be totallv gone, sup- 

 posing such an event possible, the then persevering of the waters 

 still and unfrozen, spite of the freezing cold superinduced upon 

 their neighbourhood by the grand processes of nature, would be no 

 benefit to the world with respect to warmth; hut r,he formation 

 anew, and perpetual new accumulation of ice would, on the con- 

 trary, furnish a perpetual supply of caloric to warm the world, 

 or temper the severity of the cold produced by other causes in- 

 dependent of the existence of these waters. 



That there has been a tendency of late years in the ice round 

 the north pole to melt and not to accumulate, may be plausibly 

 inferred from what has been noticed of late of its breaking up, and 

 detaching itself in masses. We observe ice to break and detach 

 (and become what the boys call rotten) in thawing weather; while 

 its thickness shall be still double or triple of what, in the con- 

 trary state of the atmosphere, would have ensured its firmness and 

 J;jlie adhesion of its parts together. 



XXXiV. On 



