Entered, according to Act of Congress, in the year 1856.

BY BLANCHARD AND LEA,

In the Clerk's Office of the District Court for the Eastern District of Pennsylvania.

C. SHERMAN & SON, PRINTERS,

19 St. James Street.

PREFACE TO THE AMERICAN EDITION.

THE American Edition of Dr. Carpenter's Work has been reprinted with the Author's sanction, from advance sheets furnished by him to the American publishers. In assuming the supervision of the press, the Editor has been careful to leave the work as it came from the Author's hands. Such additions as seemed most required by the Students of this country have been made in the form of an Appendix. The reader will find Dr. Carpenter's reasons for omitting the Clinical Applications of the Microscope, fully detailed in his Preface; but as the various works on this subject are not readily accessible on this side of the Atlantic, it was thought that a selection from them, in a compendious form, might enhance the usefulness of the work. Free use has been made, therefore, of the excellent manuals of Beale and Bennett; and the various kindred treatises and journals have also been drawn upon. All that this portion of the work claims is to present a general view of those subjects which seem to be most required by the student of the Microscope. The growing interest in this important field of inquiry will, it is hoped, afford sufficient apology for its introduction.

A short account of American Microscopes, their modifications and accessories, has also been added, and the whole Appendix has been fully illustrated, through the liberality of the Publishers, by the addition of upwards of one hundred woodengravings.

428 WALNUT STREET,

June, 1856.

FRANCIS GURNEY SMITH, M.D.

PREFACE.

THE rapid increase which has recently taken place in the use of the Microscope,-both as an instrument of scientific research, and as a means of gratifying a laudable curiosity and of obtaining a healthful recreation,-has naturally led to a demand for information, both as to the mode of employing the instrument and its appurtenances, and as to the objects for whose minute. examination it is most appropriate. And as none of the existing Treatises, either British or Foreign, on the Microscope and its Uses, have seemed to the Author fully adapted to meet this demand (some of them being almost exclusively concerned with the Microscope itself, and others with some special branch or branches of Microscopic study), he has felt encouraged to carry out a plan which he had formed several years since; by endeavoring to combine, within a moderate compass, that information in regard to the use of his "tools" which is most essential to the working Microscopist, with such an account of the objects best fitted for his study, as might qualify him to comprehend what he observes, and might thus prepare him to benefit science, whilst expanding and refreshing his own mind.

In his account of the various forms of Microscopes and Accessory Apparatus, the Author has not attempted to describe everything which is in use in this country; still less, to go into details respecting the construction of foreign instruments. He is satisfied that in all which relates both to the mechanical and the optical arrangements of their instruments, the chief English Microscope-makers are decidedly in advance of their Continental rivals; and on this point he speaks not only from his own conviction, but from the authority of a highly accomplished German Microscopist, who has recently visited London for the

express purpose of making the comparison. Even among the products of English skill, it was necessary for him to make a selection; and he trusts that he will be found to have done adequate justice to all those who have most claim to an honorable mention.

The great objection to English Microscopes, especially on the western side of the Atlantic, seems to be their costliness; and as it can be affirmed with truth, that the instruments of Nachet, Oberhauser, and other Continental makers, are adequate for all essential purposes, a general preference is given to the latter (as the Author understands) among the Microscopists of the United States. He feels sure, however, that no one who has ever been accustomed to work with a well-constructed English Microscope will ever give the preference to a foreign instrument; and he is glad to be able to announce that one of the best London firms is now prepared to supply a Microscope of excellent quality at a price very little exceeding that paid for Continental instruments, of far superior capabilities. (See p. 103, note.)

In treating of the Applications of the Microscope, the Author has constantly endeavored to meet the wants of those who come to the study of the minute forms of Animal and Vegetable life with little or no previous scientific preparation, but who desire to gain something more than a mere sight of the objects to which their observation may be directed. Some of these may perhaps object to the general tone of his work as too highly pitched, and may think that he might have rendered his descriptions simpler by employing fewer scientific terms. But he would reply to such, that he has had much opportunity of observing, among the votaries of the Microscope, a desire for such information as he has attempted to convey (of the extent of which desire, the success of the "Quarterly Journal of Microscopical Science" is a very gratifying evidence); and that the use of scientific terms cannot be dispensed with, since there are no others in which the facts can be expressed. As he has made a point of explaining these, in the places where they are first introduced, he cannot think that any of his readers need find much difficulty in apprehending their meaning.

The proportion of space allotted to the various departments, has been determined, not so much by their Physiological importance, as by their special interest to the Microscopist; and the remembrance of this consideration will serve to account for