An example will explain this maxim. The conditions of a body, as a solid, a liquid, and an air, have been distinguished as different forms of the body. But the word form, as applied to bodies, has other meanings; so that if we were to inquire in what form water exists in a snow-cloud, it might be doubted whether the forms of crystallization were meant, or 282 the different forms of ice, water, and vapour. Hence I have proposed[23] to reject the term form in such cases, and to speak of the different consistence of a body in these conditions. The term consistence is usually applied to conditions between solid and fluid; and may without effort be extended to those limiting conditions. And though it may appear more harsh to extend the term consistence to the state of air, it may be justified by what has been said in speaking of Aphorism V.
[23] Hist. Ind. Sc. b. x. c. ii. sect. 2.
I may notice another example of the necessity of avoiding ambiguous words. A philosopher who makes method his study, would naturally be termed a methodist; but unluckily this word is already appropriated to a religious sect: and hence we could hardly venture to speak of Cæsalpinus, Ray, Morison, Rivinus, Tournefort, Linnæus, and their successors, as botanical methodists. Again, by this maxim, we are almost debarred from using the term physician for a cultivator of the science of physics, because it already signifies a practiser of physic. We might, perhaps, still use physician as the equivalent of the French physicien, in virtue of Aphorism V.; but probably it would be better to form a new word. Thus we may say, that while the Naturalist employs principally the ideas of resemblance and life, the Physicist proceeds upon the ideas of force, matter, and the properties of matter.
Whatever may be thought of this proposal, the maxim which it implies is frequently useful. It is this.
Aphorism VII.
It is better to form new words as technical terms, than to employ old ones in which the last three Aphorisms cannot be complied with.
The principal inconvenience attending the employment of new words constructed expressly for the use of science, is the difficulty of effectually introducing them. Readers will not readily take the trouble to learn the meaning of a word, in which the memory is 283 not assisted by some obvious suggestion connected with the common use of language. When this difficulty is overcome, the new word is better than one merely appropriated; since it is more secure from vagueness and confusion. And in cases where the inconveniences belonging to a scientific use of common words become great and inevitable, a new word must be framed and introduced.
The Maxims which belong to the construction of such words will be stated hereafter; but I may notice an instance or two tending to show the necessity of the Maxim now before us.
The word Force has been appropriated in the science of Mechanics in two senses: as indicating the cause of motion; and again, as expressing certain measures of the effects of this cause, in the phrases accelerating force and moving force. Hence we might have occasion to speak of the accelerating or moving force of a certain force; for instance, if we were to say that the force which governs the motions of the planets resides in the sun; and that the accelerating force of this force varies only with the distance, but its moving force varies as the product of the mass of the sun and the planet. This is a harsh and incongruous mode of expression; and might have been avoided, if, instead of accelerating force and moving force, single abstract terms had been introduced by Newton: if, for instance, he had said that the velocity generated in a second measures the accelerativity of the force which produces it, and the momentum produced in a second measures the motivity of the force.
The science which treats of heat has hitherto had no special designation: treatises upon it have generally been termed treatises On Heat. But this practice of employing the same term to denote the property and the science which treats of it, is awkward, and often ambiguous. And it is further attended with this inconvenience, that we have no adjective derived from the name of the science, as we have in other cases, when we speak of acoustical experiments and optical theories. This inconvenience has led various persons to suggest names for the Science of Heat. M. Comte 284 terms it Thermology. In the History of the Sciences, I have named it Thermotics, which appears to me to agree better with the analogy of the names of other corresponding sciences, Acoustics and Optics. Electricity is in the same condition as Heat; having only one word to express the property and the science. M. Le Comte proposes Electrology: for the same reason as before, I should conceive Electrics more agreeable to analogy. The coincidence of the word with the plural of Electric would not give rise to ambiguity; for Electrics, taken as the name of a science, would be singular, like Optics and Mechanics. But a term offers itself to express common or machine Electrics, which appears worthy of admission, though involving a theoretical view. The received doctrine of the difference between Voltaic and Common Electricity is, that in the former case the fluid must be considered as in motion, in the latter as at rest. The science which treats of the former class of subjects is commonly termed Electrodynamics, which obviously suggests the name Electrostatics for the latter.