The following pages have been written in the intervals between arduous professional engagements. Begun on the Atlantic during my voyage home from Central America, the first half relieved the tedium of a long and slow recovery from the effects of an accident occurring on board ship. The middle of the manuscript found me traversing the high passes of the snow-clad Caucasus, where I made acquaintance with the Abkassians, in whose language Mr. Hyde Clark finds analogies with those of my old friends the Brazilian Indians. I now write this brief preface and the last chapter of my book (with Bradshaw's "Continental Guide" as my only book of reference), on my way across the continent to the Urals, and beyond, to the country of the nomad Kirghizes and the far Altai mountains on the borders of Tibet; and when readers receive my work I shall probably have turned my face homewards again, and for weeks be speeding across the frozen Siberian steppes, wrapped in furs, listening to the sleigh bells, and wondering how my book has sped. It is full of theories--I trust not unsupported by facts: some thought out on the plains of Southern Australia; some during many a solitary sleigh drive over frozen lakes in North America; some in the great forests of Central and South America; some on the wide ocean, with the firmament above and below blending together on the horizon; and some, again, in the bowels of the earth when seeking for her hidden riches. The thoughts are those of a lifetime compressed into a little book; and, like the genie of the Arabian tale, imprisoned in an urn, they may, when it is opened, grow and magnify, or, on the contrary, be kicked back into the sea of oblivion. This much is necessary; not to disarm criticism, but to excuse myself to those authors whose labours on some of the subjects I have treated of I may not have mentioned. I have, during my sojourns in England, worked hard to read up the literature of the various questions discussed, but I know there must be many oversights and omissions in referring to what others have done; especially with regard to continental writers, for I know no language but my mother-tongue; and their works, excepting where I have had access to translations, have been sealed books to me.