The fundamental terms of a system of Nomenclature may be conveniently borrowed from casual or arbitrary circumstances.
For instance, the names of plants, of minerals, and of geological strata, may be taken from the places where they occur conspicuously or in a distinct form; as Parietaria, Parnassia, Chalcedony, Arragonite, Silurian system, Purbeck limestone. These names may be considered as at first supplying standards of reference; for in order to ascertain whether any rock be Purbeck limestone, we might compare it with the rocks in the Isle of Purbeck. But this reference to a local standard is of authority only till the place of the object in the system, and its distinctive marks, are ascertained. It would not vitiate the above names, if it were found that the Parnassia does not grow on Parnassus; that Chalcedony is not found in Chalcedon; or even that Arragonite no longer occurs in Arragon; for it is now firmly established as a mineral species. Even in geology such a reference is arbitrary, and may be superseded, or at least modified, by a more systematic determination. Alpine limestone is no longer accepted as a satisfactory designation of a rock, now that we know the limestone of the Alps to be of various ages.
Again, names of persons, either casually connected with the object, or arbitrarily applied to it, may be employed as designations. This has been done most copiously in botany, as for example, Nicotiana, Dahlia, Fuchsia, Jungermannia, Lonicera. And Linnæus has laid down rules for restricting this mode of perpetuating the memory of men, in the names of plants. Those generic names, he says[38], which have been constructed to preserve the memory of persons who have deserved well of botany, are to be religiously retained. This, he adds, is the sole and supreme reward of the botanist’s labours, and must be carefully guarded and 305 scrupulously bestowed, as an encouragement and an honour. Still more arbitrary are the terms borrowed from the names of the gods and goddesses, heroes and heroines of antiquity, to designate new genera in those departments of natural history in which so many have been discovered in recent times as to weary out all attempts at descriptive nomenclature. Cuvier has countenanced this method. ‘I have had to frame many new names of genera and sub-genera,’ he says[39], ‘for the sub-genera which I have established were so numerous and various, that the memory is not satisfied with numerical indications. These I have chosen either so as to indicate some character, or among the usual denominations, which I have latinized, or finally, after the example of Linnæus, among the names of mythology, which are in general agreeable to the ear, and which are far from being exhausted.’
[38] Phil. Bot. 241.
[39] Règne An. p. 16.
This mode of framing names from the names of persons to whom it was intended to do honour, has been employed also in the mathematical and chemical sciences; but such names have rarely obtained any permanence, except when they recorded an inventor or discoverer. Some of the constellations, indeed, have retained such appellations, as Berenice’s Hair; and the new star which shone out in the time of Cæsar, would probably have retained the name given to it, of the Julian Star, if it had not disappeared again soon after. In the map of the Moon, almost all the parts have had such names imposed upon them by those who have constructed such maps, and these names have very properly been retained. But the names of new planets and satellites thus suggested have not been generally accepted; as the Medicean stars, the name employed by Galileo for the satellites of Jupiter; the Georgium Sidus, the appellation proposed by Herschel for Uranus when first discovered[40]; Ceres Ferdinandea, 306 the name which Piazzi wished to impose on the small planet Ceres. The names given to astronomical Tables by the astronomers who constructed them have been most steadily adhered to, being indeed names of books, and not of natural objects. Thus there were the Ilchanic, the Alphonsine, the Rudolphine, the Carolinian Tables. Comets which have been ascertained to be periodical, have very properly had assigned to them the name of the person who established this point; and of these we have thus, Halley’s, Encke’s Comet, and Biela’s or Gambart’s Comet.
[40] In this case, the name Uranus, selected with a view to symmetry according to the mythological order of descent of the persons (Uranus, Saturn, Jupiter, Mars) was adopted by astronomers in general, though not proposed or sanctioned by the discoverer of the new planet. In the cases of the smaller planets, Ceres, Pallas, Juno, and Vesta, the names were given either by the discoverer, or with his sanction. Following this rule, Bessel gave the name of Astræa to a new planet discovered in the same region by Mr. Hencke, as mentioned in the additions to book vii. of the History (2nd Ed.). Following the same rule, and adhering as much as possible to mythological connexion, the astronomers of Europe have with the sanction of M. Le Verrier, given the name of Neptune to the planet revolving beyond Uranus, and discovered in consequence of his announcement of its probable existence, which had been inferred by Mr. Adams and him (calculating in ignorance of each other’s purpose) from the perturbations of Uranus; as I have stated in the Additions to the Third Edition of the History.
In the case of discoveries in science or inventions of apparatus, the name of the inventor is very properly employed as the designation. Thus we have the Torricellian Vacuum, the Voltaic Pile, Fahrenheit’s Thermometer. And in the same manner with regard to laws of nature, we have Kepler’s Laws, Boyle or Mariotte’s law of the elasticity of air, Huyghens’s law of double refraction, Newton’s scale of colours. Descartes’ law of refraction is an unjust appellation; for the discovery of the law of sines was made by Snell. In deductive mathematics, where the invention of a theorem is generally a more definite step than an induction, this mode of designation is more common, as Demoivre’s Theorem, Maclaurin’s Theorem, Lagrange’s Theorem, Eulerian Integrals.
In the History of Science[41] I have remarked that in the discovery of what is termed galvanism, Volta’s 307 office was of a higher and more philosophical kind than that of Galvani; and I have, on this account, urged the propriety of employing the term voltaic, rather than galvanic electricity. I may add that the electricity of the common machine is often placed in contrast with this, and appears to require an express name. Mr. Faraday calls it common or machine electricity; but I think that franklinic electricity would form a more natural correspondence with voltaic, and would be well justified by Franklin’s place in the history of that part of the subject.
[41] b. xiii. c. 1.