194 ^^^ POPULAR SCIENCE MONTHLY, 



about the varied conditions characterizing the surface of the planet 

 which we inhabit. 



In its broadest sense science is organized knowledge, and its 

 methods consist of the observation and classification of the phenom- 

 ena of which we become conscious through our senses, and the inves- 

 tigation of the causes of which these are the effects. The first step 

 in geography, as in all other sciences, is the observation and descrip- 

 tion of the phenomena with which it is concerned; the next is to clas- 

 sify and compare this empirical collection of facts, and to investigate 

 their antecedent causes. It is in the first branch of the study that 

 most progress has been made, and to it indeed the notion of geogra- 

 phy is still popularly limited. The other branch is commonly spoken 

 of as phj^sical geography, but it is more correctly the science of 

 geography. 



Tiie progress of geography has thus advanced from first rough 

 ideas of relative distance between neighboring places, to correct views 

 of the earth's form, precise determinations of position, and accurate 

 delineations of the surface. The first impressions of the differences 

 observed between distant countries were at length corrected by the 

 perception of similarities no less real. The characteristics of the 

 great regions of polar cold and equatorial heat, of the sea and land, 

 of the mountains and plains, were appreciated ; and the local varia- 

 tions of season and climate, of wind and rain, were more or less fully 

 ascertained. Later, the distribution of plants and animals, their oc- 

 currence in groups of peculiar structure in various regions, and the 

 circumstances under w^hich such groups vary from place to place, gave 

 rise to fresh conceptions. Along with these facts were observed the 

 peculiarities of the races of men their physical form, languages, cus- 

 toms, and history exhibiting on the one hand striking differences in 

 different countries, but on the other often connected by a strong 

 stamp of similarity over large areas. 



By the gradual accumulation and classification of such knowledge 

 the scientific conception of geographical unity and continuity was at 

 length formed, and the conclusion established that while each differ- 

 ent part of the earth's surface has its special characteristics, all ani- 

 mate and inanimate Nature constitutes one general system, and that 

 the particular featui-es of each region are due to the operation of uni- 

 versal laws acting under varying local conditions. It is upon such a 

 conception that is now brought to bear the doctrine, very generally 

 accepted by the naturalists of our own country, that each successive 

 phase of the earth's history, for an indefinite period of time, has been 

 derived from that which preceded it, under the operation of the forces 

 of Nature as we now find them ; and that, so far as observation justi- 

 fies the adoption of any conclusions on such subjects, no change has 

 ever taken place in those forces, or in the properties of matter. This 

 doctrine is commonly spoken of as the (doctrine of evolution, and 



