— 16 — 



The table is prepared from the annual volumes (1897 — 

 1906) of «Annales de I'Observatoii-e physique central de St. 

 Petersbourg», especially from «Resumes mensuels et annuels». 

 The observations were made every day at 7 a. m., 1 p. m. 

 and 9 p. m. The maximum averages given are the mean of 

 the highest readings at 1 p. m., and are therefore too low be- 

 cause that hour is not the hottest part of the day. The mi- 

 nimum averages on the contrary are the mean of real minima; 

 they are not given for Petro Alexandrowsk. 



The figures on the whole correspond with those given 

 by FiCKER for another decade. 



Brackets round a figure indicate that it is not the mean 

 of 10 j^ears' observations, but only of 7 — 9 years' on account 

 of gaps in the series of observations. 



Within a territory of the size of Transcaspia there are 

 of course meteorological differences, the extent of which may 

 be seen by reference to the great «Atlas climatologique*, 

 wher ethey are charted. We need only point out here that the 

 area south of the Aral Sea has Ihe least precipitation and 

 that from this centre there is an increase on all sides. As 

 defined by Koppen this area has a true rain-less climate, the 

 rain-probability being under 0,3o. Petro-Alexandrowsk has 0,i3, 

 Askhahad 0,83, Tashkent 0,36. 



Further details are unnecessary as I do not know the ve- 

 getative conditions intimately enough to be able to correlate 

 the climatic differences with them. 



The «light- climate » of Aralocaspia is characterized by 

 the large number of cloudless days. Wiesner mentions (quo- 

 ting from Hann) that in the Kirghiz Steppe there are 170 cloudless 

 days per annum. The foliage of the plants is here aphoto- 

 metric, that is it has no fixed position in relation to the light; 

 or it is only in the lowest degree photometric, having a fixed 

 position to the light (Wiesner p. 62). This is in the main 

 correct, yet plants occur which turn their leaves in accor- 

 dance with the light, for example Glycyrrhiza and Smirnowia. 



