THE PLANET EARTH

Articles first published in the Scientific American which deal with earth as a series of concentric spheres, treat of the successive sections -- the lithosphere (articles on the earth's interior, crust, heat)- the hydrosphere, (circulation of the oceans, glacier masses, etc.) -- and the atmosphere (its circulation, the ionosphere). Addressed to the layman, this should add to the average reader's knowledge of our identity in the galaxy.