PREFACE.

That there was need of a book on the subject of which this treats, will be evidenced to those who examine its contents. Whether this book meets the need, it is for those to decide who are its readers.

The circumstances of its writing are recited in its opening chapter. I was urged to the undertaking by valued friends. At every step in its progress I have been helped by those friends, and others. For much of that which is valuable in it, they deserve credit. For its imperfections and lack, I alone am at fault.