-1859] WRITINGS OF JOSEPH HENRY. H 



the general principles of which these facts are the result. 

 All the phenomena of the atmosphere should be studied and 

 traced to the laws on which they depend. The labor be- 

 stowed upon investigations of this kind is not (as the narrow- 

 sighted advocate of immediate utilitarian results would 

 affirm) without practical importance ; on the contrary, it is 

 the basis of the highest improvement of which the art of 

 agriculture is susceptible. On every acre of ground a defi- 

 nite amount of solar force is projected, which may under 

 proper conditions be employed in developing organization ; 

 and the great object of the husbandman is to so arrange the 

 conditions, that the least possible amount of this may be lost 

 in un-economical results. Independently however of the 

 practical value of a knowledge of the principles on which the 

 art of agriculture depends, the mind of the farmer should be 

 cultivated as well as his fields, and after the study of God's 

 moral revelation, what is better fitted to improve the intel- 

 lect than the investigation of the mode by which He pro- 

 duces the changes in the material universe? 



The climate and productiveness of a country are deter- 

 mined, first, by its latitude, or its distance on either side of 

 the equator ; second, by the configuration of the surface as 

 to elevation and depression; third, by its position, whether 

 in the interior of a continent or in proximity to the ocean ; 

 fourth, by the direction and velocity of the prevailing winds; 

 fifth, by the nature of the soil ; and lastly, by the cultiva- 

 tion to which it has been subjected. 



First, in regard to latitude : The productive power of a 

 soil (other things being the same) depends on two circum- 

 stances, — solar radiation and moisture ; and these increase 

 as we approach the equator. 



If the kind of food were a matter of indifference, the same 

 extent of ground which supports one person at the latitude 

 of 60° would support twenty-five at the equator ; but the 

 food necessary to the support of persons in different lati- 

 tudes varies with respect to quality as well as to quantity; 

 and the other conditions mentioned, with regard to climate, 

 should enter largely into the estimate we form in relation 

 to the actual productiveness of different parallels of latitude. 



