Hot and Thermal Springs. WfB 



dersdorf. He determined the mean temperature of the surfj^e 

 of the Sauberg at 44°.94. The result of several years' observa- 

 tions in the St Christoph shaft, which lies to the wQ&t^ ,and is 

 the least exposed to the cold, was 42°.22, at thirty-one feet be- 

 low the surface ; the same temperature was found in the jVIor- 

 genrother cross-cut, lying to the east of this shaft, at a depth 

 of 281 feet from the surface. The temperature is, then, consi- 

 derably lower than the mean temperature of the surface, as 

 weU near the surface as at a greater depth. In the Sauberg 

 the ice is seldom found lower than fourteen fathoms ; how- 

 ever, it was once observed in the interstices of the Old Man, ai 

 much as twenty-four fathoms below the surface. Reich found 

 the temperature of the ice to be 31°.982, the air in the im- 

 mediate vicinity 34''.025, and the rock at a little distance 

 32°.765.* 



At many other places, in the Erzgebirge, the temperature of 

 the soil was found, on the contrary, to be higher than that of 

 the air, viz. : — 



At Mark us Rtihling the temperature of the soil, as well as of 

 the air, is remarkably low, in comparison to its elevation abpve 



• For further information on ice-caverns and ice-grottos, see Gehler's 'Neues 

 Ph^^sik Worterbuch, vol. iii. part i. p. 150, and following; and Reich, p. 

 188, and following. It is related of several such ice-grottos, that the ice is 

 only there in summer, and that it thaws away in winter. By referring to 

 the three years' observations on the temperature of the St Christoph shaft, 

 we find that the maximum occurs in November, and the minimum in April ; 

 so that the opinion that the mines are colder in summer than in winter is easily 

 accounted for. If a spot could be found, whose mean temperature was ex- 

 actly 32°, ice would be found to continue to increase there till June or even 

 July ; and, on the other hand, to decrease until December or January. But 

 the one would nevertheless be the effect of the preceding winter, and the 

 other that of" the preceding summer. Also, according to the observations of 

 X)r Oudot (Journ. des Mines, t. iv. No. 21. p. 65), the ice in the celebrated 

 cavern of Besan9on, near La Chaux, increases till April, and decreases till 

 October: in January the tt>niperature falls to 20.°f, in summer it rises to 

 38°. 2. We see, then, that the..e variations correspond very nearly with those 

 observed in springs, which is nothing else than might be expected. 



ft Reich, p. 122. 



Bb2 



