The purpose of this book is to assist in the discovery and proof of the facts in any investigation, or legal inquiry, involving the genuineness of a document. Definite instructions are given regarding the investigation of the several classes of questioned documents. Since the first edition of this book was issued eighteen years ago there has been a revolution in many American courts in the methods and procedure relating to the proof of the facts in disputed document cases. It can hardly be believed now that less than fifteen years ago no standard of comparison, no genuine writing whatever, could be introduced, either to prove genuineness or forgery, in the United States federal courts, or in the state courts of many states. In the great majority of courts, however, there is now a helpful and receptive attitude that tends to make a trial at law involving a disputed document, as it should be, a legally supervised scientific investigation. Courts are more and more distinguishing between mere opinions and clear, demonstrative evidence; between honest and competent witnesses and dishonest and incompetent fakirs and pretenders. A hope is again expressed that this new and enlarged work will aid in promoting justice.