PREFACE.
The book here presented to the reader is the legacy to science of Dr. John Snow. The completion of the work was his last act and deed. In editing the book, therefore, all that remained to be done consisted in the construction of the index, and in this a plan suggested by the author himself has been followed.
In contributing the memoir, I have performed a painful and unexpected duty: the fulfilment of a promise given at a moment when two friends who often enjoyed close companionship met at one of their happiest meetings. The promise was given with the idea of fulfilment far distant, or improbable altogether, and, as connected with a more extended biographical survey, reserved for the work of years long in the future; it is called for now hastily and in deep sorrow.
Writing with the fact of my late friend’s death not as yet fully realized; with the sensation still on me at intervals (like one who has lost a part of his own body, and yet at times conceives the lost present), that he cannot possibly be so far away; I may, perchance be pardoned for any deficiencies in style or matter. I have done my best, and leave it so.