University of Virginia Library

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xxvi

PREFACE TO THE SECOND EDITION

In this new edition some slight corrections have been
made in the text; and a supplemental list, containing additions
and corrections, has been subjoined to the Directory
of the Names of Underground Operators in the Appendix.

The author will be under obligations to those who call his
attention to any other points requiring change. It is more
than pleasant to be able to thank the reviewers and the
public for the kindly reception accorded this book.