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[1].
- ↑ "Were any further reasoning necessary to overthrow it, (namely, the voltaic theory of contact) a forcible argument might be drawn from the following consideration. If there could exist a power, having the property ascribed to it by the hypothesis, namely, that of giving continual impulse to a fluid in one constant direction, without being exhausted by its own action, it would differ essentially from all the other known powers in nature. All the powers and sources of motion with the operation of which we are acquainted, when producing their peculiar effects, are expended in the same proportion as those effects are produced ; and hence arises the impossibility of obtaining by their agency a perpetual effect, or, in other words, a perpetual motion. But the electro-motive force ascribed by Volta to the metals when in contact, is a force which, as long as a free course is allowed to the electricity it sets in motion, is never expended, and continues to be exerted with undiminished power, in the production of a never-ceasing effect. Against the truth of such a supposition the probabilities are all but infinite." § 113, p. 32.
