Page:Proceedings of the Royal Society of London Vol 4.djvu/242

Rh fects would be, he thinks, to deny that action and reaction are equal. The contact theory, according to him, assumes that a force which is able to overcome powerful resistance, both chemical and mechanical, can arise out of nothing : that, without any change in the acting matter, or the consumption of any other force, an electric current can be produced, which shall go on for ever against a con- stant resistance, or only be stopped, as in the voltaic trough, by the ruins which its exertion has heaped in its own course ; — this, the author thinks, would be a creation of power, such as there is no example of in nature ; and, as there is no difficulty in converting electrical into mechanical force through the agency of magnetism, it would, if truBy supply us at once with a per[3etual motion. Such a conclusion he considers as a strong and sufficient proof that the theory of contact is founded in error.

In a postscript, the author states that he has since found a passage in Dr. Roget's treatise on Galvanism, in the Library of Useful Knowledge, published in January 1829, in which the same argument respecting the unphilosophical nature of the contact-theory is strongly urged.