Spectacles and Eyeglasses/Preface
Since the publication of the first edition the author has frequently had the pleasure of hearing from students of ophthalmology that they had found in it information of which they had often experienced the need, but which is not usually supplied by works on their special subject. In preparing the present edition the aim has been to add an account of such real and lasting improvements in spectacles as have been introduced since the first edition was published.
The portions relating to prisms have been revised and rewritten in accordance with the now well established reform in the numeration of prisms. Several new tables and a few new cuts have been added. Simplicity of diction has been kept in view, to the end that the book might present its subject, not only fresh, but in a form readily intelligible to the elementary student.
August, 1895.
This little work is the outgrowth of the instruction on the subject of prescribing spectacle frames which has been given to successive classes at the Philadelphia Polyclinic and College for Graduates in Medicine. The book, like the teaching referred to, is intended to supplement studies in refraction, and to give the student that knowledge of the correct placing of the glasses before the eyes without which the most painstaking measurement of the refraction will frequently fail of practical result. With the popularization, as one may call it, of ophthalmology in the profession, many physicians who prescribe glasses are compelled, by the lack of skilled opticians in their neighborhood, to themselves furnish the spectacles to the patient. To these, it is believed, the knowledge which I have endeavored to impart in these pages will prove especially useful.
Of late years much advance has been made in the art of making efficient, comfortable, and handsome contrivances for holding glasses before the eyes, and the increased use of prismatic and cylindrical lenses has given the fitting of the frames increased importance. Text-books of refraction remain, however, almost devoid of reference to the subject, the scant literature of which is scattered through opticians' trade publications and a few medical periodicals. Free application has been made to such sources, and the indebtedness incurred duly acknowledged in the text.
My thanks are due to my friend and instructor, Dr. Edward Jackson, for many valuable suggestions in writing this treatise, and, indeed, for directing my attention to the need of a book on spectacles.
Dr. George M. Gould kindly furnished me with some references used in the introduction, and I am indebted to Messrs. Wall & Ochs, Bonschur & Holmes, and J. W. Queen & Co. for a number of cuts.
March, 1892.