Hot and Thermal Springs. S59 



where volcanic fire also shews itself, as, for example, in Iceland,* 

 on the Lipari Islands,f and Las Trincheras near Puerto Cabello^ 

 in the Corderillas.| But some sprinojs would certainly reach the 

 surface with a higher temperature, did they not meet on their way 

 with colder ones ; and springs running in narrow channels must 

 cool more rapidly than in larger ones. 



Chap. V. — The Temperature of Springs being a function of that 

 of the Meteoric Waters^ and of the strata of the earth through 

 which theyjlowy it is required to determine whether the Variations 

 of the Temperature of the Meteoric Waters also shew themselves 

 in Thermal Springs, 



Springs which only pass through those strata which partici- 

 pate in the variations of the external temperature, must them- 

 selves have a variable temperature. The table at the end of the 

 next chapter, which contains my own observations on the tem- 

 perature of springs, as well as all those of others which have 

 come to my knowledge, affords many examples of such variable 

 springs. 



As in our latitude the yearly mean temperature of the air oc- 

 curs about April and October, its maximum in July, and its 

 minimum in January, it will be seen by the Table, that the 

 variations of temperature of some few springs keep an equal 

 pace with those of the air. In mo^t cases they follow one, two, 

 or even three months later.g Th; depends on the depth below 

 the surface in which the course of ihose springs lie, the quanti- 

 ty of water they yield, and the power of conducting heat pos- 

 sessed by the soil. The deeper springs flow, the less abundant 

 their waters ; and the less the degree of conductibility of heat of 

 the soil, the later will the seasons of their temperature follow those 

 of the air. The differences between the annual maximum and 

 minimum temperature of springs are, in general, greater the 



• Gilbert's Annalen. vol. xliiL p. 54. 



-|- PoggendorfTs Annal. voL xxvL p. 67. 



X Annales de Cbimie et Phys. vol. lii. p. 181. 



5 In the Journ. de Phys. vol. IxviiL p. 224, it is asserted that the minimum 

 temperature of springs happens at the time of the maximum temperature^ 

 the air, and vice versa ; for a thermometer, which was suspended in a well of 

 34 feet deep at Geneva from 179G to 1805, gave a maximum of 54.275 ia 

 December 1804, &nd a minimum of 48°.425 in June 1798. 



Aa2 



