FOREWORD
Except for its characters and plot, this book is not a work of the imagination.
The methods which the fictitious Trant—one time assistant in a psychological laboratory, now turned detective—here uses to solve the mysteries which present themselves to him, are real methods; the tests he employs are real tests.
Though little known to the general public, they are precisely such as are being used daily in the psychological laboratories of the great universities—both in America and Europe—by means of which modern men of science are at last disclosing and defining the workings of that oldest of world-mysteries—the human mind.
The facts which Trant uses are in no way debatable facts; nor do they rest on evidence of untrained, imaginative observers. Innumerable experiments in our university laboratories have established beyond question that, for instance, the resistance of the human body to a weak electric current varies when the subject is frightened or undergoes emotion; and the consequent variation in the strength of the current, depending directly upon the amount of emotional disturbance, can be registered by the galvanometer for all to see. The hand resting upon an automatograph will travel toward an object which excites emotion,
