IxiV NOTES. 



Eduard Hallmann, at his former residence at Marienberg, near Boppard, on the 

 Rhine, observed during five years (from December 1, 1845, to November 30, 

 1850), the temperature of the air, the quantity of rain, and the temperature of 

 seven different springs; and founded, on these observations, a new and revised 

 examination of the question of the " Temperatur-Verhaltnisse der Quellen." He 

 excluded springs of thoroughly constant temperature (geological springs), in- 

 cluding only such as undergo a variation of temperature in the course of the 

 year. These " variable springs " fall under two natural groups : 



I) Purely meteorological springs, . e., whose mean temperature is demon- 

 strably not heightened by terrestrial heat. In these, the amount of deviation 

 from the mean atmospheric temperature of the place is dependent on the distri- 

 bution of the fall of rain in the different seasons. Such springs are, on the 

 mean, colder than the air, when the quantity of rain falling in the four cold 

 months, from December to March inclusive, is more than a third of the whole 

 quantity falling in the entire year; and they are, on the mean, warmer than the 

 air, when the rain falling in the four warm months, July to October, exceeds 

 one third of the whole. The negative or positive departure from the atmospheric 

 mean is the greater, the greater the excess of rain in either the cold or the warm 

 season. Those springs, in which the deviation from the atmospheric mean is the 

 greatest and most accordant with the actual distribution of rain in the year, are 

 regarded as giving "undisfigured means;" while those, in which the deviation 

 from the atmospheric mean has been diminished by the disturbing influence of 

 the temperature of the air when no rain falls, are classed as giving " approximate 

 means " (both, however, coming under the general head of " purely meteorological 

 springs "). The too near approximation of the mean to the atmospheric mean 

 is a consequence either of the mode of obtaining the result such as the 

 temperature being measured at the lower end of a channel or pipe coming from 

 the spring, or of the spring itself having a superficial course, and of the 

 poverty of supply. Of the Marienberg springs, four belong to the group of 

 " purely meteorological springs," and of these four, one has an undisfigured 

 mean, and the other three, in different degrees, approximate means. In the 

 first observation-jear, the fall of rain was in excess in the cold third of the 

 year, and all the four springs were, in their means, colder than the air; in each 

 of the four following years, more than a third of the year's rain fell in the 

 wanner four months, and all the springs were, in their means, warmer than the 

 air, and the deviation was, in each year, proportionate to the amount of the 

 excess of warm rain. 



Thus the view put forward by Von Buch in 1825, that the amount of devia- 

 tion of the mean temperature of springs from the mean atmospheric temperature 



