2784 OR, THE PLAIN WHY AND BECAUSE. FAMILIARIZING SUBJECTS OF USEFUL CURIOSITY AND BY JOHN TIMBS, Editor of Laconics:' 'Arcana of Science and Art,' &c. "Its beginning is pleasure, its progress knowledge, and its objects truth Zoological Series. BOSTON: LILLY & WAIT, AND CARTER & HENDEE. NEW-YORK, E. BLISS; PHILADELPHIA, CAREY AND HART; Gist Tappan Presb, Ass 12-31-1931 KNOWLEDGE FOR THE PEOPLE: OR THE PLAIN WHY AND BECAUSE. PART VII.-MECHANICS. B MECHANICS. INTRODUCTORY. Why are certain truths termed physical? Because they explain the greater part of the phenomena of nature, the term physical being derived from the Greek word signifying nature; an appellation distinguishing them from chemical truths, which regard particular substances, and from vital truths, which have relation only to living bodies.—Arnott. Why is an atom so called? Because of its origin from a Greek word signifying that which cannot be farther divided; or, an exceedingly minute resisting particle. Why is the term attraction used? Because the atoms of which the visible universe is built up, whether separate, or already joined into masses, tend towards all other masses, with force proportioned to their proximity: as, when any body presses or falls towards the great mass of the earth, or when the tides on the earth rise towards the moon. Why is the term repulsion used? Because, under certain known circumstances, as of heat diffused among the particles, their mutual attraction is countervailed or resisted, and they tend to separate with force proportioned to their proximity : as, when heated water bursts into steam, or when gunpowder explodes. |