is based on the Italian translation, I have made many further
corrections and changes of arrangement of the original matter; I have
rewritten a considerable portion of the work, and have made, in the text
and in notes, numerous and important additions, founded partly on
observations of my own, partly on those of other students of Physical
Geography, and though my general conclusions remain substantially the
same as those I first announced, yet I think I may claim to have given
greater completeness and a more consequent and logical form to the whole
argument

Since the publication of the original edition, Mr. Elisee Reclus, in the
second volume of his admirable work, La Terre (Paris, 1868), lately made
accessible to English-reading students, has treated, in a general way,
the subject I have undertaken to discuss. He has, however, occupied
himself with the conservative and restorative, rather than with the
destructive, effects of human industry, and he has drawn an attractive
and encouraging picture of the ameliorating influences of the action of
man, and of the compensations by which he, consciously or unconsciously,
makes amends for the deterioration which he has produced in the medium
he inhabits. The labors of Mr. Reclus, therefore, though aiming at a
much higher and wider scope than I have had in view, are, in this
particular point, a complement to my own. I earnestly recommend the work
of this able writer to the attention of my readers.

George P. Marsh

Rome, May 1, 1878.