The lectures which the author delivered last winter, at King's College, and which were published in the Medical Times and Gazette in the Spring, and his paper in the last volume of the Philosophical Transactions form the basis of the present memoir.
It need hardly be said, that the great expense of illustrating his researches in the usual way would have precluded the author from bringing them forward in a separate form ; moreover, the sale of a work lie the present must necessarily be very small, as the subject can only be interesting to a limited number of readers. Feeling the necessity of illustrations, he determined, to attempt, although against the advice of some, to take photographs of his drawings. For the success which has attended this effort he is mainly indebted to the asistance and encouragement he has received from several friends who are interested in photography.
The author sees great reason to hope that the plan which has been adopted will be found of great practical utility in illustrating scientific treatises, of which only a few copies are required. In those cases, however, where a considerable number is wanted, the expense of photographs would be much greater than that of engravings, and the length of time required to print them forms a considerable obstacle to their use on a large scale.
For the illustration of scientific subjects the necessary exactness of photographs offers great advantages, and some anatomical structures may be delineated far more like nature in this manner than by engraving. The illustrations in the present volume must not be regarded, by any means, as the most perfect which can be obtained ; indeed, several which have since been made have caused the author to become very dissatisfied with those published, many of which were taken directly from the original drawings of specimens of diseased livers in every respect far superior to any in the present volume. Some copies have also been obtained from the objects themselves, which the author hopes to publish at some future time.
In spite of the help and valuable instructions he has received from many kind friends, especially from Mr. Hardwich and from his friend and pupil, Mr. Julius Pollock, the author can only look upon himself as a most indifferent photographer, with a very few months' experience ; and he feels that some apology is due from him to those more skilful and experienced than himself, for the wrong he has done their beautiful art, in bringing forward some decidedly bad pictures in a photographic point of view. These delineations may, nevertheless, be sufficiently good to render his views upon the structure of the liver intelligible ; for without illustrations, he fears it would be almost impossible for any one to understand his meaning.
Several of the best negatives were kindly taken by Mr. Pollock.
The prints have been worked off in the author's private laboratory.
It may be interesting here to give an account of the cost of producing these prints. The paper employed was double-crown, at twenty shillings per ream of 26lbs., and was obtained of Messrs. Richards, of St. Martin's Lane.
Cost per 100 copies of each single page : —
|Nitrate of Silver||1||6|
|Hyposulphite of Soda||0||2|
|Solution of Chloride of Gold||0||3|
One person can finish from 100 to 150 per day, and if the image were brought out by development many more might be obtained in the same time.
The author feels deeply indebted to his friend and colleague, Mr. Bowman, for much valuable advice and for many suggestions when he was prosecuting his researches, which have rendered the labour not only lighter but far more pleasurable than it could otherwise have been.
27 Carey Street,
September 20th, 1856.