In the following pages I have endeavoured to give some account of the ways in which scientific discovery has been utilised in the struggle between society and the criminal.

I have tried to describe the principles upon which different kinds of scientific evidence are based, and at the same time to bring human interest into what would otherwise tend to be dry detail by giving an outline of trials in which such evidence has been given. It is, perhaps, hardly necessary to mention that in many of these illustrative trials the accused persons were proved innocent of the charges brought against them, and that although their cases were tried in the criminal courts the title of the book in no way applies to them.

For the accounts of the older trials I have drawn freely upon Cobbett’s State Trials, Paris and Fonblanque’s Medical Jurisprudence, and the first edition of Taylor’s Medical Jurisprudence, while I must also acknowledge my indebtedness to the Circumstantial Evidence of Mr. Justice Wills and the recent excellent lectures on Forensic Chemistry, by Mr. Jago.

In the later cases I have mainly relied upon contemporary accounts and upon my own impressions of some of the trials at which I have been present.My best thanks are due to all those who have given me valuable and ungrudging assistance. In particular I would mention Major Richardson, who has kindly given me a photograph of one of his trained bloodhounds and has allowed me to quote the description of an actual man hunt with bloodhounds, from his book, War, Police, and Watch Dogs; and Mademoiselle Arlette Clary (and the Daily Mirror) who have supplied me with a photograph of a Paris police dog.

I am further indebted to the late Sir Francis Galton and his publishers, Messrs. Macmillan & Co., who gave me permission to reproduce illustrations from his book on Finger Prints; and to Mr. Thorne Baker and the Daily Mirror for photographs illustrating the use of telegraphy in transmitting portraits.

The excellent drawings of the hairs of different animals were made by my friend Mr. R. M. Prideaux, and are reproduced here by the kind permission of Messrs. Scott Greenwood & Co.

Finally, I would thank the proprietors of Knowledge and the Editor, Mr. Wilfred Mark Webb, for the loan of various blocks and for permitting me to make use of material from several articles of mine on handwriting, which have appeared in that journal.

C. A. M.

White Cottage,
Amersham Common,
Buckinghamshire.