414 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



where C m and C n indicate the quantities of heat that are required 

 at Munich and Nukuss respectively to warm up the unit volume of 

 the respective soils by i°C. 



Unfortunately we are not able to say anything as to the values 

 of these quantities except that they can scarcely be smaller than 

 300 or greater than 600. 18 



However, the numbers 35 and 48 as just given for Munich and 

 Nukuss are still affected with great uncertainty since the data for 

 Munich begins first at 1.29 meters depth whilst those for Nukuss 

 end at 4 meters, so that in one case we must extrapolate upward, 

 in the other case downward. In fact this extrapolation downward 

 is necessary in both cases although to a less extent in the series for 

 Munich. 



As values of the diurnal exchange we obtained for Nukuss 0.56 C n 

 in January and 1.5 C n in July, but again of course only a crude 

 approximation. 



However, these numbers suffice to show the general magnitude 

 of the part that the solid ground plays as a reservoir of heat or a 

 regulator of temperature. 



Thus, in order to deal with round numbers assume briefly that 

 C n = C m = 500, then would the quantity of heat exchanged within 

 the annual period suffice to evaporate a layer of water 30 milli- 

 meters deep at Munich and 40 millimeters deep at Nukuss. 



Therefore, compared with the depth of the total rainfall which 

 amounts to 8oo mm in Munich but only 85™"* in Nukuss, the 

 result is that the quantity of heat absorbed into the ground during 

 the warm season at Munich but given out again during the cold 

 season is scarcely i/26th part of that required to re-evaporate the 

 annual precipitation, and even in Nukuss, the driest region of the 

 whole Euro-Asian continent, it is not one-half. 



On the other hand, the quantity of heat exchanged at Nukuss 

 within the diurnal period is much larger than required for the evap- 

 oration of the average daily rainfall at that place. 



Of course it must not be forgotten that the heat used in evapora- 

 tion goes partly to maintain the temperature of the upper strata, 

 so that the quantities of heat exchanged within the ground must 

 on this account appear somewhat smaller than they really are. 



18 See von Liebenberg: Ueber den gegenwartigen Stand der Bodenphysik. 

 Wollny, Forschungen., Vol. I, 187S, p. 3. And further C. Lang: Warme- 

 kapazitat der Boden-konstituanten. Forschungen I, p. 109. Compare 

 also' Ad. Schmidt fSchriften'd. physik-oekonomische Gesellschaft zur K&nigs- 

 berg in Preussen, XXXII, 1891, p. 123. 



