Читать книгу A Treatise on Mechanics онлайн

11 страница из 91

It may be here, once for all, observed, that the phraseology of causation and hypotheses has become so interwoven with the language of science, that it is impossible to avoid the frequent use of it. Thus, we say, “the magnet attracts iron;” the expression attract intimating the cause of the observed effect. In such cases, however, we must be understood to mean the effect itself, finding it less inconvenient to continue the use of the received phrases, modifying their signification, than to introduce new ones.

Force, when manifested by the mutual approach or cohesion of bodies, is also called attraction, and it is variously denominated, according to the circumstances under which it is observed to act. Thus, the force which holds together the atoms of solid bodies is called cohesive attraction. The force which draws bodies to the surface of the earth, when placed above it, is called the attraction of gravitation. The force which is exhibited by the mutual approach, or adhesion, of the loadstone and iron, is called magnetic attraction, and so on.