which are chiefly important in their relation to the condition of
the Indian tribes. The Older Period of barbarism, which commences
with the introduction of the art of pottery, and the Middle Period,
which commences with the use of adobe brick in the construction of
houses, and with the cultivation of maize and plants by irrigation,
mark two very different and very dissimilar conditions of life. The
larger portion of the Indian tribes fall within one or the other of
these periods. A small portion were in the Older Period of savagery,
and none had reached the Later Period of barbarism, which
immediately precedes civilization. In treating of the condition of
the several tribes they will be assigned to the particular period to
which they severally belong under this classification.

I regret to add that I have not been able, from failing health, to
give to this manuscript the continuous thought which a work of any
kind should receive from its author. But I could not resist the
invitation of my friend Major J. W. Powell, the Director of the
Bureau of Ethnology, to put these chapters together as well as I
might be able, that they might be published by that Bureau. As it
will undoubtedly be my last work, I part with it under some
solicitude for the reason named; but submit it cheerfully to the
indulgence of my readers.

I am greatly indebted to my friend Mr. J. C. Pilling, of the same
Bureau, for his friendly labor and care in correcting the proof
sheets, and for supervising the illustrations. Such favors are very
imperfectly repaid by an author's thanks.

The late William W. Ely, M. D., LL. D., was, for a period of more
than twenty-five years, my cherished friend and literary adviser,