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Natural History of Volcanos and Earthquakes. 75 
mean temperatute is 50°.6 F, and exceeds the mean temperature — 
of the soil by about 1°.7, present already a uniform degree of 
heat. Thus, on the 21st May, 1834, I found the temperature of 
the Alme at Brenken, 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 51°. The miller there, whose mill is turned 
by one of these springs (what is called the Vé/meder 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 
Perceptibly 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 issue from high 
Situated channels, which contained 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 Alme 
came mudy, and the Vélmeder 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 Pader springs. This circumstance 1s 
also a Satisfactory proof of the great extent of the subterraneous 
Teservoir, because, notwithstanding the fact, that the sinking 
Miers aud 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- 
Wently which rise from a greater depth, run out clear. 
T 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 
Hvers of our latitude, and when from it is discharged an equal 
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