Note (return) — Chapter XIV · VOYAGE ROUND THE WORLD, BY CAPTAIN GEORGE ANSON, IN THE YEARS 1740-1744.1 (continued 4)

If it should be asked, how it comes then to pass, that the heat, in many places between the tropics, is esteemed so violent and insufferable, when it appears, by these instances, that it is sometimes rivalled, and even exceeded, in very high latitudes, not far from the polar circle? I shall answer, That the estimation of heat, in any particular place, ought not to be founded upon that particular degree of it which may now and then obtain there; but is rather to be deduced from the medium observed during a whole season, or perhaps in a whole year; and in this light, it will easily appear how much more intense the same degree of heat may prove, by being long continued without remarkable variation. For instance, in comparing together St Catharines and St Petersburg, we shall suppose the summer heat at St Catharines to be 76°, and the winter heat to be only 56°. I do not make this last supposition upon sufficient authority, but am apt to suspect the allowance is full large. Upon this supposition, therefore, the medium heat all the year round will be 66°; and this perhaps by night as well as by day, with no great variation. Now, those who have attended to thermometrical observation will readily allow, that a continuance of this degree of heat for a length of time, would be found violent and suffocating by the generality of mankind. But at Petersburg, though the heat, as measured by the thermometer, may happen to be a few times in the year considerably higher than at St Catharines, yet, at other times, the cold is intensely sharper, and the medium for a year, or even for one season only, would be far short of 60°. For I find, that the variation of the thermometer at Petersburgh, is at least five times greater, from its highest to its lowest point, than I have supposed it to be at St Catherines.2