NOTES. Ixv 



must depend on the distribution of the fall of rain within the annual period, has 

 been found perfectly correct by Hallmann, so far at least as his own station of 

 Marienberg, in the Rhenish greywacke, is concerned. It is only " purely meteo- 

 rological springs of undisfigured means " that are of value for scientific clima- 

 tology; such springs ought, therefore, to be sought for everywhere for this 

 object, in contradistinction from " purely meteorological springs of approxi- 

 mate means " on the one hand, and from " meteorolo-geological springs " on the 

 other. 



2) Meteorolo-geological springs are such as have temperatures demonstrably 

 raised by the earth's heat. In these, whatever may be the distribution of the 

 fall of rain in the year, the mean is always higher than the atmospheric mean 

 (the variations which they show in the course of the year are imparted to them 

 by the ground through which they flow). The amount of their excess of mean 

 temperature over that of the air depends on the depth to which the meteoric 

 waters sink before reappearing as a spring, and has, therefore, no climatological 

 interest. The climatologist ought to know them, that he may not mistake them 

 for purely meteorological springs ; they may also, of course, present more or less 

 approximation to the atmospheric mean, by reason of any channel through which 

 their waters may be conducted to the point where their temperature is observed. 

 The springs were observed on fixed days, four or five times a month. The 

 height above the sea of the place of observation for atmospheric temperature, as 

 well as that of each of the different springs, was also noted. 



Dr. Hallmann, after completing and reducing his Marienberg observations, 

 spent the winter of 1852 1853 in Italy; and found in the Apennines, besides 

 ordinary springs, some " abnormally cold springs." He gives this name to "springs 

 which can be shown to bring with them a lower degree of temperature from 

 heights. They are to be regarded as subterranean outlets, either from open lakes 

 situated high in the mountains; or from subterranean reservoirs, from which the 

 water descends in mass, and very rapidly, through cracks and fissures, and comes 

 out, at the foot of the hills, as a spring. The idea of an abnormally cold 

 spring is therefore, that it is too cold for the height at which it issues forth, or 

 rather that it issues forth at a part of the mountain too low down for its low 

 temperature." These views, given by Dr. Hallmann in the first volume of his 

 " Temperatur-Verhaltnisse der Quellen," are somewhat modified in the second 

 volume, S. 181 183, where he allows that all springs, even the most super- 

 ficial, contain some portion of warmth derived from the earth. 



( 285 ) p. 207. Humboldt, Asie Centrale, t. ii. p. 58. Respecting the reasons 

 which render it more than probable that the Caucasus, which at f of its length, 

 between Kasbegk and Elburuz,in the mean parallel of 42 50', runs E.S.E. 

 VOL. IV e 



