Has many things in common with both astronomy and geology, as it discusses the physical condition of the earth and its relations as a member of the solar system; describes its great natural divisions of land and water; and takes account of dynamic forces, such as aerial and oceanic currents, that are constantly causing important changes. The whole exterior structure of the earth, the phenomena of rain and dew, fog, frost, and snow, are geographical questions, to be discussed with special reference to the general laws or principles involved. It shows unity in the midst of diversity, and constancy of phenomena in the midst of apparent changes.
MATHEMATICAL GEOGRAPHY
Treats of the form and size of the earth, of the construction of globes to represent it; determines the latitude and longitude of places on its surface, and all geographical problems pertaining to numbers, distances, and magnitudes.
POLITICAL GEOGRAPHY
Describes, in a general way, the countries and nations of men as they are politically divided, defines their boundaries, and to some extent characterizes their social and civil institutions. A great advance has been made in this branch during the present century. People respecting whom little was known, have come into the family of nations. The maps have been changed, and generally in a way that indicates the rapid progress of civilization. Asia has been so thoroughly explored that our general knowledge of the country may be regarded as nearly complete. No great terra incognita remains in that quarter, though fuller and more precise knowledge respecting the people in some parts is yet much to be desired. The interior of Africa is still but partially known, though the work of discovery has been pushed forward with considerable enterprise, and a host of explorers have struggled to penetrate the mystery that enveloped, for ages, that great division of the globe. The Upper Nile country has been explored far beyond the region assigned on the maps to the “Mountains of the Moon,” and all know the intense anxiety that is to-day felt for the safety of General Gordon and his little garrison, still shut up in Khartoum.
The study of geography, rightly pursued, is remunerative, full of inspiration, and as intensely interesting as any in the whole circle of physical sciences.
BIOLOGY
Is scientific discourse about life and vital forces. We give it a high position in the circle, since vitality is superior to either chemical or mechanical laws, suspending or modifying them for the production of organized structures of plants and animals. Even vegetable biology confronts us with that mystery of mysteries, life, which is quite inexplicable. We can only say it is a peculiar, indefinable something, necessary to the existence of such organisms, and without which they soon sink in ruinous decay.
The living germ is the determining power that shapes the organic body, and every germ will have its own body. Under no possible culture can the acorn develop into an animal. It will produce an oak, a tree of its own species, and nothing else can grow from it. So also of the animal germ. The form or kind is as determinate while the embryo is yet in the egg, as it will ever be. The life once begun in everything that lives and grows, there is a power that takes hold of the elements nature has in store for it, and, by a most wonderful transformation, works them up into its own body; and this power of assimilation must forever distinguish it from all lifeless inorganic matter.
The mystery deepens when we notice that living things exist in generations. The plant has seed in itself for the production of another plant. It has life in itself, and power to vitalize its successors. The products of the field and the forest grow and mature, then wither and decay; but they have successors of the same kind.