10 



ART. 7.— Y. HOMM.A 



-1°.9 îit 3005 m.; -2\2 :it 3105 m.; ~2\l at oO(i() m. Again on the 

 occasion of tlie international Italloon ascents on .Ian. 10, 11)01,'^ a 

 balloon from Menna recorded tlie following temperatures : -4°.G at 



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500 m.; VrJ at 1000 m.; 0°.2 at 2000 m. Another from Berlin 

 recorded ; -8°.6 at the starting ; 0°.0 at 790 m.; 5°.0 at 14(]0 m.; 0°.2 

 at 2825 m. 



Of course these will differ somewhat from the minimum tem- 

 peratures of the day at the respective altitudes. But the difference, 

 I believe, will be at most onlv a deijree or two ; for accordino- to 

 Hergesell, -^ the diurnal variatioris of the temperature at higher 

 altitudes are very small, am(3unting, for instance, to o° or -1° at 800 m., 

 when the sky is clear, and much less wdien it is overcast. Also the 

 days on wdiich the above mentioned ascensions were made may be 

 regarded as typical winter days with liigli pressure and severe frost on 

 the ground, so that we may believe that the atmospheric conditions 

 then observed are normal, and not exceptional. The meteorological 



1) Xiitur." LXIII. p. 353. 1901. 



2) Herj^esell, l\'termann"s Geographische Mitteilungen Pt. V. 1900. 



