[56] Hooker, Brit. Flo. p. 450. Hymenophyllum Wilsoni, Scottish filmy fern, abundant in the highlands of Scotland and about Killarney.
Other characters, as well as form, are conveyed with the like precision: Colour by means of a classified scale of colours, as we have seen in speaking of the [Measures] 317 of Secondary Qualities; to which, however, we must add, that the naturalist employs arbitrary names, (such as we have already quoted,) and not mere numerical exponents, to indicate a certain number of selected colours. This was done with most precision by Werner, and his scale of colours is still the most usual standard of naturalists. Werner also introduced a more exact terminology with regard to other characters which are important in mineralogy, as lustre, hardness. But Mohs improved upon this step by giving a numerical scale of hardness, in which talc is 1, gypsum, 2, calc spar 3, and so on, as we have already explained in the History of Mineralogy. Some properties, as specific gravity, by their definition give at once a numerical measure; and others, as crystalline form, require a very considerable array of mathematical calculation and reasoning, to point out their relations and gradations. In all cases the features of likeness in the objects must be rightly apprehended, in order to their being expressed by a distinct terminology. Thus no terms could describe crystals for any purpose of natural history, till it was discovered that in a class of minerals the proportion of the faces might vary, while the angle remained the same. Nor could crystals be described so as to distinguish species, till it was found that the derived and primitive forms are connected by very simple relations of space and number. The discovery of the mode in which characters must be apprehended so that they may be considered as fixed for a class, is an important step in the progress of each branch of Natural History; and hence we have had, in the History of Mineralogy and Botany, to distinguish as important and eminent persons those who made such discoveries, Romé de Lisle and Haüy, Cæsalpinus and Gesner.
By the continued progress of that knowledge of minerals, plants, and other natural objects, in which such persons made the most distinct and marked steps, but which has been constantly advancing in a more gradual and imperceptible manner, the most important and essential features of similarity and dissimilarity in such objects have been selected, arranged, and fitted with 318 names; and we have thus in such departments, systems of Terminology which fix our attention upon the resemblances which it is proper to consider, and enable us to convey them in words.
The following Aphorisms respect the Form of Technical Terms.
By the Form of terms, I mean their philological conditions; as, for example, from what languages they may be borrowed, by what modes of inflexion they must be compounded, how their derivatives are to be formed, and the like. In this, as in other parts of the subject, I shall not lay down a system of rules, but shall propose a few maxims.
Aphorism XX.
The two main conditions of the Form of technical terms are, that they must be generally intelligible, and susceptible of such grammatical relations as their scientific use requires.
These conditions may at first appear somewhat vague, but it will be found that they are as definite as we could make them, without injuriously restricting ourselves. It will appear, moreover, that they have an important bearing upon most of the questions respecting the form of the words which come before us; and that if we can succeed in any case in reconciling the two conditions, we obtain terms which are practically good, whatever objections may be urged against them from other considerations.
1. The former condition, for instance, bears upon the question whether scientific terms are to be taken from the learned languages, Greek and Latin, or from our own. And the latter condition very materially affects the same question, since in English we have scarcely any power of inflecting our words; and therefore must have recourse to Greek or Latin in order to obtain terms which admit of grammatical modification. If we were content with the term Heat, to express the science of heat, still it would be a bad technical term, for we cannot derive from it an adjective like 319 thermotical. If bed or layer were an equally good term with stratum, we must still retain the latter, in order that we may use the derivative Stratification, for which the English words cannot produce an equivalent substitute. We may retain the words lime and flint, but their adjectives for scientific purposes are not limy and flinty, but calcareous and siliceous; and hence we are able to form a compound, as calcareo-siliceous, which we could not do with indigenous words. We might fix the phrases bent back and broken to mean (of optical rays) that they are reflected and refracted; but then we should have no means of speaking of the angles of Reflection and Refraction, of the Refractive Indices, and the like.
In like manner, so long as anatomists described certain parts of a vertebra as vertebral laminæ, or vertebral plates, they had no adjective whereby to signify the properties of these parts; the term Neurapophysis, given to them by Mr. Owen, supplies the corresponding expression neurapophysial. So again, the term Basisphenoid, employed by the same anatomist, is better than basilar or basial process of the sphenoid, because it gives us the adjective basisphenoidal. And the like remark applies to other changes recently proposed in the names of portions of the skeleton.