ELEMENTS 



OF 



NATURAL PHILOSOPHY, 



A TEXT-BOOK 



FOR HIGH SCHOOLS AND ACADEMIES, 



BY 



ELROY M. AVERY, Pn.M., 



PRINCIPAL OF THE EAS T HI G I! SCHOOL, CLEVELAND, OHIO 



ILLUSTRATED BY NEARLY 400 WOOD ENGRAVINGS. 



NEW YORK-. 



SHELDON & COMPANY, 



No. 8 MURRAY STREET. 



1881. 



