Allan Pinkerton 
The Spiritualists and the Detectives [EPUB ebook] 

I WISH to anticipate any adverse criticism that may be made upon the following pages, by being as frank with the public as I trust the critics will be fair with me.
Therefore I must say at the beginning that I expect many well-meaning people to differ with me as to the propriety of giving this book to the public; but I am exceedingly hopeful that that difference will not amount to a serious condemnation. Nor can I think it will when I earnestly assert that I have caused its publication out of as honest a motive as I ever possessed; and I am sure that whatever the American people have come to think of me in other respects, they are pretty certain of my honesty.