114 SPRINGS, BIVEKS, CANALS, LAKES, 



believing. It is easy to see the source of M. de Mairan's error ; 

 he has founded his calculations on the scale of Reaumur, and con- 

 siders the degrees of his thermometer as marking the real propor- 

 tions, and absolute quantity of heat. It is a matter that cannot 

 be denied, that we know nothing of the absolute quantities of heat; 

 and that the degrees of the thermometers are only to be considered 

 as a few of the middle links of a chain, the length of which we are 

 totally ignorant of, and therefore in no condition to compare its 

 proportional parts. It deserves however to be remarked, that the 

 observations of a late date have shown, that the notions of cold on 

 which Reaumur's scale was constructed, and on which M. de 

 Mairan's calculations are founded, are imaginary and without foun- 

 dation. 



The sea admits of change of temperature more July 63^* 

 quickly than the earth, particularly near the shore. Aug. 63|* 

 The mean heat of [the sea at Brighthelmstone, dur. Sept. 58 

 ing the months of July, Aug. Sept. and Oct. was as Oct. 53* 

 annexed: 



The wells at New York are from 32 to 40 feet in depth, and 

 Dr. Nooth found them to have an annual variation of 2, from 54 

 to 56. There are few countries, in which the annual range of the 

 thermometer is greater than at New York, and the neighbouring 

 parts of America. In the summer it is often as high as 96, and 

 in winter it has been observed several degrees below the zero of 

 Fahrenheit's scale. On the whole, we may, from all the observa- 

 tions we are yet in possession of, conclude, that there is at present 

 no source of heat in the earth, capable of affecting the temperature 

 of a country, which is not derived from the sun ; and that the earth 

 whatever changes of temperature it may be conjectured to have 

 undergone in former periods, is now reduced to a mean of the 

 heat produced by the sun in different seasons, and in different 

 climates. [PA//. Trans. Abr. Vol. xvi. 



3. The Caldeira of St. Michael. 



To this island we have already had occasion to allude to on 

 another account. We shall now return to it in order to describe 

 its tepid and hot springs, which we cannot possibly do more cor. 

 rectly than in the following extract from a paper of Mr. Francb 

 Masson, inserted iu the Journal of the Royal Society. 



