Imperial Academy of Sciences of St Petersburg. 107 



of Europe in the thorny, but useful, research into the periodi- 

 city of all the magnetic phenomena. 



If the resolution of the problem which I have just pointed 

 out, is equally important for the physical history of our planet 

 and the improvement of the art of navigation, the second object 

 which I have to lay before you, and for which the extent of the 

 empire presents immense advantages, is more immediately con- 

 nected with general wants, — the cultivation of the soil, the exa- 

 mination of the configuration of the ground, the exact know- 

 ledge of the humidity of the air, which visibly deci'eases with 

 the destruction of the forests and the diminution of the water of 

 lakes and rivers. The first and noblest object of science re- 

 sides undoubtedly in themselves, in the enlargement of the 

 sphere of ideas, and of the intellectual power of man. It is not 

 in the bosom of an academy like yours, under the monarch who 

 regulates the destinies of the empire, that the research of great 

 physical truths requires the support of a material and external 

 interest, of an immediate application to the wants of social 

 life ; but when the sciences, without deviating from their noble 

 primary object, are capable of exercising a direct influence upon 

 agriculture and the arts (which are too exclusively called use- 

 ful), it is the duty of the philosopher to point out these rela- 

 tions between the scientific investigation of countries, and the 

 increase of territorial riches. 



A country which extends over more than 135 degrees of 

 longitude, from the happy zone of the olive to the climates in 

 which the ground is only covered with lichens, is more than any 

 other capable of advancing the study of the atmosphere, the 

 knowledge of the mean temperatures of the year, and, what is 

 much more important for the cycle of vegetation, that of the 

 distribution of the annual heat among the different seasons. 

 Add to these data for obtaining a group of facts intimately 

 connected with each other, the variable pressure of the air, and 

 the relation of this pressure to the predominant winds and the 

 temperature, the extent of the horary variations of the barome- 

 ter (which under the tropics, transform a tube filled with mer- 

 cury into a kind of time-piece of most imperturbable regularity 

 in its progress), the hygrometric state of the air, and the annual 

 quantity of rain, which it is of so much importance to the 

 agriculturist to know. When the varied inflections of the 



