OF NATURAL PHILOSOPHY; IN WHICH THE PRINCIPLES OF MECHANICS, HYDROSTATICS, HYDRAULICS, PNEUMATICS, ACOUSTICS, OPTICS, ARE FAMILIARLY EXPLAINED, AND ILLUSTRATED BY MORE THAN TWO HUNDRED ENGRAVINGS. TO WHICH ARE ADDED, QUESTIONS FOR THE EXAMINATION OF THE PUPILS DESIGNED FOR THE USE OF SCHOOLS AND ACADEMIES. Third (Stereotype) Edition. BY J. L. COMSTOCK, M. D. Mem. Con. M. S.; Hon. Mem. R. I. M. S.; Author of Notes to Conv. on Chemistry; Hartford: PUBLISHED BY D. F. ROBINSON & CO. SOLD BY COLLINS & HANNAY, J. LEAVITT, AND R. LOCKWOOD, NEW-YORK; TOWAR, STEREOTYPED BY JAMES CONNER, NEW-YORK. Edurt 218.32.300 HARVARD COLLEGE LIBRARY GIFT OF GEORGE ARTHUR PLIMPTON DISTRICT OF CONNECTICUT, ss. BE IT REMEMBERED, That on the twenty-fourth day of May, m the fifty-fifth year of the Independence of the United States of America, J. L. COMSTOCK, of the said District, hath deposited in this office the title of a Book, the right whereof he claims as author and proprietor, in the words following, to wit; "A System of Natural Philosophy; in which the principles of Mechanics, Hydrostatics, Hydraulics, Pneumatics, Acoustics, Optics, Astronomy, Electricity, and Magnetism, are familiarly explained, and illustrated by more than two hundred engravings. To which are added, Questions for the examination of the Pupils. Designed for the use of Schools and Academies. By J. L. Comstock, M. D.; Mem. Con. Med. Soc.; Hon. Mem. R. I. M. S.; Author of Notes to Conv. on Chem.; Author of Gram. Chem.; of Elem. Mineralogy; of Nat. Hist. of Quadr. and Birds, &c." In conformity to the act of Congress of the United States, entitled, "an act for the encouragement of learning, by securing the copies of Maps, Charts, and Books, to the authors and proprietors of such copies, during the times therein mentioned."-And also to the act, entitled, "an act supplementary to an act, entitled, 'an act for the encouragement of learning, by securing the copies of Maps, Charts, and Books, to the authors and proprietors of such copies, during the times therein mentioned,' and extending the benefits thereof to the arts of designing, engraving, and etching historical and other prints." CHARLES A. INGERSOLL, Clk. of the Dis. of Connecticut. A true copy of Record, examined and sealed by me, CHARLES A. INGERSOLL, Clk. of the Dis. of Connecticut. PREFACE. WHILE We have recent and improved systems of Geography, of Arithmetic, and of Grammar, in ample variety,--and Reading and Spelling Books in corresponding abundance, many of which show our advancement in the science of education, no one has offered to the public, for the use of our schools, any new or improved system of Natural Philosophy. And yet this is a branch of education very extensively studied at the present time, and probably would be much more so, were some of its parts so explained and illustrated as to make them more easily understood. The author therefore undertook the following work at the suggestion of several eminent teachers, who for years have regretted the want of a book on this subject, more familiar in its explanations, and more ample in its details, than any now in common use. The Conversations on Natural Philosophy, a foreign work now exten sively used in schools, though beautifully written, and often highly interesting, is, on the whole, considered by most instructors as exceedingly deficient particularly in wanting such a method in its explanations, as to convey to the mind of the pupil precise and definite ideas; and also in the omission of many subjects, in themselves most useful to the student, and at the same time most easily taught. It is also doubted by many instructors, whether Conversations is the best form for a book of instruction, and particularly on the several subjects embraced in a system of Natural Philosophy. Indeed, those who have had most experience as teachers, are decidedly of the opinion that it is not; and hence we learn, that in those parts of Europe where the subject of education has received the most attention, and consequently where the best methods of conveying instruction are supposed to have been adopted, school books in the form of conversations are at present entirely out of use. The author of the following system hopes to have illustrated and explained most subjects treated of, in a manner so familiar as to be understood by the pupil, without requiring additional diagrams, or new modes of explanations from the teacher. Every one who has attempted to make himself master of a difficult proposition by means of diagrams, knows that the great number of letters |