METEOROLOGY IN EUSSIA. 



281 



was observed west of the plateaus, on the upper Irtyscli and east of 

 them at Pekin. The following table shows the distribution of pressure 

 in different months : 



TVcMcrn Europe. 



Eeikia vig, (Iceland) j 29. 47 



.70 

 .51 

 .(13 



.38 



Greenwich 



Hammerpest, Xorway 

 Hdine, North Italy ... 

 Vienna 



NortJi and West Russia. 



Archangel 



St. Peter.sbui'g 



Kostrom.a . ...; 



Warsaw 



Kiev 



Eastern Asia. 



Irkutsk 



Nertichinsk 

 Pekin 



28.78 

 27.96 

 30.24 



20. G9 

 .81 

 .73 

 .58 

 .30 



.70 

 .78 

 .15 

 .44 

 .67 



28.19 

 27. 56 

 29.67 



South and East Russia. 



Odessa 



Lxigan 



Samara 



Orenburg 



Astracau 



Caucasus. 



Eedut Kale. 



Tiflis 



Baku 



West Siberia and Central 

 Abia. 



Bogoslovsk .... 

 Catherinburg . . 



Barnaul 



JTovo Petrovsk 



.SO 



.87 



.09 

 28. 55 

 30.21 



29.28 



29.13 



.81 



30.08 



29. 67 

 .48 

 .43 

 .44 



29. 88 



.84 

 28.29 

 29.81 



29.05 

 28.78 

 29.10 



The monthly differences of pressure have only lately attracted general 

 attention. The cause of this is that in Western Europe, Eastern North 

 America, and the tropics, these differences are very small. It was only 

 after the observations in Siberia, China, and India were known, that the 

 barometrical depression of the summer was noticed, and the summer 

 monsoon of India and China was explained by the rarefaction of the 

 air in the middle of the continent, and the consequent drawing in of the 

 air of the surrounding seas. 



Now that the relations of the pressure to the winds are better known, 

 much more attention is given to barometrical observations, and espe- 

 cially those of the A.siatic continent attract the attention of all me- 

 teorologists. There are two problems which remain to be solved here 

 in regard to this matter : (1) Barometrical observations in the interior of 

 Asia, to ascertain the true amount of summer depression at a distauce 

 from the influence of the ocean, and (2) a line of levels from the Baltic 

 to the Pacific Ocean. So long as the true height of Siberian points of 

 observation is not known, and the ado]>ted heights may be wrong from 

 300 to 500 feet, we can know very little of the pressure of the air in this 

 region. It is a circulus vitiosus, as the heights are measured by the 

 barometer, and afterwards the observed barometrical readings are reduced 

 to sea-level, on the supposition that the obtained height is true. The 

 isobars drawn in Buchan's excellent work on the mean pressure are not 

 free from this reproach, as any isobars must be so long as the actual 

 height is not accurately known. The plan of a line of levels from the 



