Natural History of Volcanos and Earthquakes. 75 



mean temperatute is 50^.6 F, and exceeds the mean temperature 

 of the soil by about l^.Tj present ah'eady a uniform degree of 

 heat. Thus, on the 21st May, 1834, I found the temperature of 

 the Abne at Brenkeii^ where considerable masses of the water 

 of this river flow down through the clefts of the chalk, to be 63^, 

 while the springs at Geseke, at the distance of 22^000 feet, which 

 doubtless receive their supply from this river, were of the tem- 

 perature of 49"^ to Sl*^. The miller there, whose mill is turned 

 by one of these springs (what is called the Volmeder spring,) 



told me he had often opened the holes found on the banks 

 of the Alme, and let in as much water as would have been alone 

 sufficient to turn his mill, but that he never perceived the slight- 

 est increase of the streams. This also proves the great extent of 

 the subterraneous reservoir of water, whose discharges are not 

 perce])tibly increased by an addition of water. If, indeed, these 

 additions are continued by continued wet weather, and the level 

 of the subterraneous reservoir rises, then, not only will those 

 springs become more copious, but water will also issne from high 

 situated channels, which contaizied no water during the dry sea- 

 son. .Lastly, the same miller assured me that the muddiness of 

 his mill streams by no means depended on that of the Alme, 

 since they always become so after rain. Opinions were, how- 

 ever, divided on this point, as other inhabitants of Geseke main- 

 tained, that, within twelve or sixteen hours after rain, the Alrne 

 became mudy, and the Volmeder springs became so too, while 

 this had no influence on the springs in the town. Be this as it 

 will, thus much is certain, that all the springs there do not be- 

 come muddy after rain, but that many always remain clear, as 

 the warmer among the Fader springs. This circumstance is 

 also a satisfactory proof of the great extent of the subterraneous 

 reservoir, because, notwithstanding the fact, that the sinking 

 rivers and brooks, as well as the rain-water and snow-water, 

 which penetrate into the fissures of the fissured rock, are all 

 muddy in rainy weather, yet the warmer springs, those conse- 

 quently which rise from a greater depth, run out clear. 



I have instituted some experiments in order to ascertain what 

 must be the extent of a single mass of water, which retains a 

 uniform temperature, when a given quantity of water is added to 

 it, whose temperature varies with the variable temperature of the 



rivers of our latitude, and when from it is discharged an equal 



