106 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Russia, and lias applied to those stations whose altitudes 

 were correctly known by levelings the barometric reduc- 

 tions (as computed by Ruhlmann's formula) necessary in or- 

 der to reduce the observed pressures to the theoretical sea- 

 level. The highest station to which he has applied this proc- 

 ess is Tiflis, whose altitude is about 1500 feet, and at which 

 altitude he states the reduction to sea-level already becomes 

 quite uncertain. The longest series of observations employed 

 by him is, for the Russian stations, that at Warsaw, embrac- 

 ing thirty-three years. Having reduced the annual pressures 

 to sea-level for these stations, he has, by means of prelimi- 

 nary approximate isobars, determined the mean annual press- 

 ure at sea-level for the other stations whose altitudes were 

 not correctly known, and has there computed the altitudes as 

 dependent upon long series of good observations, of five in- 

 terior stations, with a probable accuracy of less than forty feet, 

 and has determined the altitude of eight other stations with 

 an error of less than ten feet. These secondary stations thus 

 became valuable in the formation of the monthly isobars, 

 although, of course, they can not be used on the annual 

 charts. The final charts thus completed by RikatcheiF pre- 

 sent the same phenomena as those given by Buchan, but of 

 not quite so extreme a nature. The change from a very 

 high pressure in the interior of the continent during the win- 

 ter to a low barometer in the summer time is very decided- 

 ly marked (the explanation of this phenomenon given by Ri- 

 katcheflfis too much at variance with mechanical laws to es- 

 cape severe criticism). On the other hand, the annual chart 

 shows a well-marked diminution in the average barometric 

 pressure as we proceed northward. Its depression lie attrib- 

 utes to the numerous cyclones that occur in this region, al- 

 though he states very plainly that the average annual tem- 

 perature, as well as the tension of aqueous vapor, should con- 

 spire to annul this effect. It is probable that at the time of 

 composing his memoir he had not yet become acquainted 

 with the writings of Ferrel, Thomson, Peslin,Colding,Everett, 

 and others, by whom the depression of the barometer in the 

 polar regions of the earth is very accurately explained as due 

 to the rotation of the earth on its axis, combined with the 

 general atmospheric currents. Ferrel has even explained, in 

 a very perspicuous manner, the reason why this depression is 



