Chapter XXVI: Introduction (2)

_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.

The subject of the Tides is, in like manner, destitute of any name which designates the science concerned about it. I have ventured to employ the term _Tidology_, having been much engaged in tidological researches.

Many persons possess a peculiarity of vision, which disables them from distinguishing certain colours. On examining many such cases, we find that in all such persons the peculiarities are the same; all of them confounding scarlet with green, and pink with blue. Hence they form a class, which, for the convenience of physiologists and others, ought to have a fixed designation. Instead of calling them, as has usually been done, 'persons having a peculiarity of vision,' we might take a Greek term implying this meaning, and term them _Idiopts_.

But my business at present is not to speak of the selection of new terms when they are introduced, but to illustrate the maxim that the necessity for their introduction often arises. The construction of new terms will be treated of subsequently. {285}

APHORISM VIII.

_Terms must be constructed and appropriated so as to be fitted to enunciate simply and clearly true general propositions._

THIS Aphorism may be considered as the fundamental principle and supreme rule of all scientific terminology. It is asserted by Cuvier, speaking of a particular case. Thus he says[24\4] of Gmelin, that by placing the lamantin in the genus of morses, and the siren in the genus of eels, he had rendered every general proposition respecting the organization of those genera impossible.

[Note 24\4: _Règne Animal_, Introd. viii.]

The maxim is true of words appropriated as well as invented, and applies equally to the mathematical, chemical, and classificatory sciences. With regard to most of these, and especially the two former classes, it has been abundantly exemplified already, in what has previously been said, and in the _History of the Sciences_. For we have there had to notice many technical terms, with the occasions of their introduction; and all these occasions have involved the intention of expressing in a convenient manner some truth or supposed truth. The terms of Astronomy were adopted for the purpose of stating and reasoning upon the relations of the celestial motions, according to the doctrine of the sphere, and the other laws which were discovered by astronomers. The few technical terms which belong to Mechanics, _force_, _velocity_, _momentum_, _inertia_, &c., were employed from the first with a view to the expression of the laws of motion and of rest; and were, in the end, limited so as truly and simply to express those laws when they were fully ascertained. In Chemistry, the term _phlogiston_ was useful, as has been shown in the _History_, in classing together processes which really are of the same nature; and the nomenclature of the _oxygen_ theory was still preferable, because it enabled the chemist to express a still greater number of general truths. {286}

To the connexion here asserted, of theory and nomenclature, we have the testimony of the author of the oxygen theory. In the Preface to his _Chemistry_, Lavoisier says:--'Thus while I thought myself employed only in forming a Nomenclature, and while I proposed to myself nothing more than to improve the chemical language, my work transformed itself by degrees, without my being able to prevent it, into a Treatise on the Elements of Chemistry.' And he then proceeds to show how this happened.

It is, however, mainly through the progress of Natural History in modern times, that philosophers have been led to see the importance and necessity of new terms in expressing new truths. Thus Harvey, in the Preface to his work on Generation, says:--'Be not offended if in setting out the History of the Egg I make use of a new method, and sometimes of unusual terms. For as they which find out a new plantation and new shores call them by names of their own coining, which posterity afterwards accepts and receives, so those that find out new secrets have good title to their compellation. And here, methinks, I hear Galen advising: If we consent in the things, contend not about the words.'

The Nomenclature which answers the purposes of Natural History is a Systematic Nomenclature, and will be further considered under the next Aphorism. But we may remark, that the Aphorism now before us governs the use of words, not in science only, but in common language also. Are we to apply the name _fish_ to animals of the whale kind? The answer is determined by our present rule: we are to do so, or not, accordingly as we can best express true propositions. If we are speaking of the internal structure and physiology of the animal, we must not call them _fish_; for in these respects they deviate widely from fishes: they have warm blood, and produce and suckle their young as land quadrupeds do. But this would not prevent our speaking of the _whale-fishery_, and calling such animals _fish_ on all occasions connected with this employment; for the relations thus arising depend upon the animal's living in the water, and being caught in a {287} manner similar to other fishes. A plea that human laws which mention fish do not apply to whales, would be rejected at once by an intelligent judge.

[A bituminiferous deposit which occurs amongst the coal measures in the neighbourhood of Edinburgh was used as coal, and called 'Boghead Cannel Coal.' But a lawsuit arose upon the question whether this, which geologically was not _the coal_, should be regarded in law as _coal_. The opinions of chemists and geologists, as well as of lawyers, were discrepant, and a direct decision of the case was evaded.[25\4]]

[Note 25\4: Miller's _Chemistry_, iii. 98.]

APHORISM IX.

_In the Classificatory Sciences, a Systematic Nomenclature is necessary; and the System and the Nomenclature are each essential to the utility of the other._

THE inconveniences arising from the want of a good Nomenclature were long felt in Botany, and are still felt in Mineralogy. The attempts to remedy them by _Synonymies_ are very ineffective, for such comparisons of synonyms do not supply a systematic nomenclature; and such a one alone can enable us to state general truths respecting the objects of which the classificatory sciences treat. The _System_ and the _Names_ ought to be introduced together; for the former is a collection of asserted analogies and resemblances, for which the latter provide simple and permanent expressions. Hence it has repeatedly occurred in the progress of Natural History, that good Systems did not take root, or produce any lasting effect among naturalists, because they were not accompanied by a corresponding Nomenclature. In this way, as we have already noticed, the excellent botanical System of Cæsalpinus was without immediate effect upon the science. The work of Willoughby, as Cuvier says[26\4], forms an epoch, and {288} a happy epoch in Ichthyology; yet because Willoughby had no Nomenclature of his own, and no fixed names for his genera, his immediate influence was not great. Again, in speaking of Schlotheim's work containing representations of fossil vegetables, M. Adolphe Brongniart observes[27\4] that the figures and descriptions are so good, that if the author had established a nomenclature for the objects he describes, his work would have become the basis of all succeeding labours on the subject.

[Note 26\4: _Hist. des Poissons_, Pref.]

[Note 27\4: _Prodrom. Veg. Foss._ p. 3.]

As additional examples of cases in which the improvement of classification, in recent times, has led philosophers to propose new names, I may mention the term _Pœcilite_, proposed by Mr. Conybeare to designate the group of strata which lies below the oolites and lias, including the new red or variegated sandstone, with the keuper above, and the magnesian limestone below it. Again, the transition districts of our island have recently been reduced to system by Professor Sedgwick and Mr. Murchison; and this step has been marked by the terms _Cambrian_ system, and _Silurian_ system, applied to the two great groups of formations which they have respectively examined, and by several other names of the subordinate members of these formations.

Thus System and Nomenclature are each essential to the other. Without Nomenclature, the system is not permanently incorporated into the general body of knowledge, and made an instrument of future progress. Without System, the names cannot express general truths, and contain no reason why they should be employed in preference to any other names.

This has been generally acknowledged by the most philosophical naturalists of modern times. Thus Linnæus begins that part of his Botanical Philosophy in which names are treated of, by stating that the foundation of botany is twofold, _Disposition_ and _Denomination_; and he adds this Latin line, Nomina si nescis perit et cognitio rerum. {289} And Cuvier, in the Preface to his _Animal Kingdom_, explains, in a very striking manner, how the attempt to connect zoology with anatomy led him, at the same time, to reform the classifications, and to correct the nomenclature of preceding zoologists.

I have stated that in Mineralogy we are still destitute of a good nomenclature generally current. From what has now been said, it will be seen that it may be very far from easy to supply this defect, since we have, as yet, no generally received system of mineralogical classification. Till we know what are really different species of minerals, and in what larger groups these species can be arranged, so as to have common properties, we shall never obtain a permanent mineralogical nomenclature. Thus _Leucocyclite_ and _Tesselite_ are minerals previously confounded with Apophyllite, which Sir John Herschel and Sir David Brewster distinguished by those names, in consequence of certain optical properties which they exhibit. But are these properties definite distinctions? and are there any external differences corresponding to them? If not, can we consider them as separate species? and if not separate species, ought they to have separate names? In like manner, we might ask if _Augite_ and _Hornblende_ are really the same species, as Gustavus Rose has maintained? if _Diallage_ and _Hypersthene_ are not definitely distinguished, which has been asserted by Kobell? Till such questions are settled, we cannot have a fixed nomenclature in mineralogy. What appears the best course to follow in the present state of the science, I shall consider when we come to speak of the form of technical terms.

I may, however, notice here that the main Forms of systematic nomenclature are two:--terms which are produced by combining words of higher and lower generality, as the binary names, consisting of the name of the genus and the species, generally employed by natural historians since the time of Linnæus;--and terms in which some relation of things is indicated by a change in the form of the word, for example, an alteration of its termination, of which kind of {290} nomenclature we have a conspicuous example in the modern chemistry.

APHORISM X.

_New terms and changes of terms, which are not needed in order to express truth, are to be avoided._

AS the Seventh Aphorism asserted that novelties in language may be and ought to be introduced, when they aid the enunciation of truths, we now declare that they are not admissible in any other case. New terms and new systems of terms are not to be introduced, for example, in virtue of their own neatness or symmetry, or other merits, if there is no occasion for their use.

I may mention, as an old example of a superfluous attempt of this kind, an occurrence in the history of Astronomy. In 1628 John Bayer and Julius Schiller devised a _Cœlum Christianum_, in which the common names of the planets, &c., were replaced by those of Adam, Moses, and the Patriarchs. The twelve Signs became the twelve Apostles, and the constellations became sacred places and things. Peireskius, who had to pronounce upon the value of this proposal, praised the piety of the inventors, but did not approve, he said[28\4], the design of perverting and confounding whatever of celestial information from the period of the earliest memory is found in books.

[Note 28\4: Gassendi, _Vita Peireskii_, 300.]

Nor are slight anomalies in the existing language of science sufficient ground for a change, if they do not seriously interfere with the expression of our knowledge. Thus Linnæus says[29\4] that a fair generic name is not to be exchanged for another though apter one: and[30\4] if we separate an old genus into several, we must try to find names for them among the synonyms which describe the old genus. This maxim excludes the restoration of ancient names long disused, no less than the needless invention of new ones. Linnæus {291} lays down this rule[31\4]; and adds, that the botanists of the sixteenth century well nigh ruined botany by their anxiety to recover the ancient names of plants. In like manner Cuvier[32\4] laments it as a misfortune, that he has had to introduce many new names; and declares earnestly that he has taken great pains to preserve those of his predecessors.

[Note 29\4: _Phil. Bot._ 246.]

[Note 30\4: _Ib._ 247.]

[Note 31\4: _Phil. Bot._ 248.]

[Note 32\4: _Règne Anim._ Pref. xvi.]

The great bulk which the Synonymy of botany and of mineralogy have attained, shows us that this maxim has not been universally attended to. In these cases, however, the multiplication of different names for the same kind of object has arisen in general from ignorance of the identity of it under different circumstances, or from the want of a system which might assign to it its proper place. But there are other instances, in which the multiplication of names has arisen not from defect, but from excess, of the spirit of system. The love which speculative men bear towards symmetry and completeness is constantly at work, to make them create systems of classification more regular and more perfect than can be verified by the facts: and as good systems are closely connected with a good nomenclature, systems thus erroneous and superfluous lead to a nomenclature which is prejudicial to science. For although such a nomenclature is finally expelled, when it is found not to aid us in expressing the true laws of nature, it may obtain some temporary sway, during which, and even afterwards, it may be a source of much confusion.

We have a conspicuous example of such a result in the geological nomenclature of Werner and his school. Thus it was assumed, in Werner's system, that his _First_, _Second_, and _Third Flötz Limestone_, his _Old_ and _New Red Sandstone_, were universal formations; and geologists looked upon it as their business to detect these strata in other countries. Names were thus assigned to the rocks of various parts of Europe, which created immense perplexity before they were again ejected. The geological terms which now prevail, for {292} instance, those of Smith, are for the most part not systematic, but are borrowed from accidents, as localities, or popular names; as _Oxford Clay_ and _Cornbrash_; and hence they are not liable to be thrust out on a change of system. On the other hand we do not find sufficient reason to accept the system of names of strata proposed by Mr. Conybeare in the _Introduction to the Geology of England and Wales_, according to which the _Carboniferous Rocks_ are the _Medial Order_,--having above them the _Supermedial Order_ (_New Red Sand_, _Oolites_ and _Chalk_), and above these the _Superior Order_ (_Tertiary Rocks_); and again,--having below, the _Submedial Order_ (the _Transition Rocks_), and the _Inferior Order_ (_Mica Slate_, _Gneiss_, _Granite_). For though these names have long been proposed, it does not appear that they are useful in enunciating geological truths. We may, it would seem, pronounce the same judgment respecting the system of geological names proposed by M. Alexander Brongniart, in his _Tableau des Terrains qui composent l'écorce du Globe_. He divides these strata into nine classes, which he terms _Terrains Alluviens_, _Lysiens_, _Pyrogenes_, _Clysmiens_, _Yzemiens_, _Hemilysiens_, _Agalysiens_, _Plutoniques_, _Vulcaniques_. These classes are again variously subdivided: thus the Terrains Yzemiens are _Thalassiques_, _Pelagiques_, and _Abyssiques_; and the Abyssiques are subdivided into _Lias_, _Keuper_, _Conchiliens_, _Pœciliens_, _Peneens_, _Rudimentaires_, _Entritiques_, _Houillers_, _Carbonifers_ and _Gres Rouge Ancien_. Scarcely any amount of new truths would induce geologists to burthen themselves at once with this enormous system of new names: but in fact, it is evident that any portion of truth, which any author can have brought to light, may be conveyed by means of a much simpler apparatus. Such a nomenclature carries its condemnation on its own face.

Nearly the same may be said of the systematic nomenclature proposed for mineralogy by Professor Mohs. Even if all his Genera be really natural groups, (a doctrine which we can have no confidence in till they are confirmed by the evidence of chemistry,) there is no {293} necessity to make so great a change in the received names of minerals. His proceeding in this respect, so different from the temperance of Linnæus and Cuvier, has probably ensured a speedy oblivion to this part of his system. In crystallography, on the other hand, in which Mohs's improvements have been very valuable, there are several terms introduced by him, as _rhombohedron_, _scalenohedron_, _hemihedral_, _systems_ of crystallization, which will probably be a permanent portion of the language of science.

I may remark, in general, that the only persons who succeed in making great alterations in the language of science, are not those who make names arbitrarily and as an exercise of ingenuity, but those who have much new knowledge to communicate; so that the vehicle is commended to general reception by the value of what it contains. It is only eminent discoverers to whom the authority is conceded of introducing a new system of names; just as it is only the highest authority in the state which has the power of putting a new coinage in circulation.

I will here quote some judicious remarks of Mr. Howard, which fall partly under this Aphorism, and partly under some which follow. He had proposed, as names for the kinds of clouds, the following: _Cirrus_, _Cirrocumulus_, _Cirrostratus_, _Cumulostratus_, _Cumulus_, _Nimbus_, _Stratus_. In an abridgment of his views, given in the Supplement to the _Encyclopædia Britannica_, English names were proposed as the equivalents of these; _Curlcloud_, _Sondercloud_, _Wanecloud_, _Twaincloud_, _Stackencloud_, _Raincloud_, _Fallcloud_. Upon these Mr. Howard observes: 'I mention these, in order to have the opportunity of saying that I do not adopt them. The names for the clouds which I deduced from the Latin, are but seven in number, and very easy to remember. They were intended as _arbitrary terms_ for the _structure_ of clouds, and the meaning of them was carefully fixed by a definition. The observer having once made himself master of this, was able to apply the term with correctness, after a little experience, to the subject under all its varieties of form, colour, or position. The {294} new names, if meant to be another set of arbitrary terms, are superfluous; if intended to convey in themselves an explanation in English, they fail in this, by applying to some part or circumstance only of the definition; the _whole_ of which must be kept in view to study the subject with success. To take for an example the first of the modifications. The term _cirrus_ very readily takes an abstract meaning, equally applicable to the rectilinear as to the flexuous forms of the subject. But the name of _curl-cloud_ will not, without some violence to its _obvious sense_, acquire this more extensive one: and will therefore be apt to mislead the reader rather than further his progress. Others of these names are as devoid of a meaning obvious to the English reader, as the Latin terms themselves. But the principal objection to English or any other local terms, remains to be stated. They take away from the nomenclature its general advantage of constituting, as far as it goes, an universal language, by means of which the intelligent of every country may convey to each other their ideas without the necessity of translation.'

I here adduce these as examples of the arguments against changing an established nomenclature. As grounds of selecting a new one, they may be taken into account hereafter.

APHORISM XI.

_Terms which imply theoretical views are admissible, as far as the theory is proved._

IT is not unfrequently stated that the circumstances from which the names employed in science borrow their meaning, ought to be facts and not theories. But such a recommendation implies a belief that facts are rigorously distinguished from theories and directly opposed to them; which belief, we have repeatedly seen, is unfounded. When theories are firmly established, they become facts; and names founded on such theoretical views are unexceptionable. If we speak of the _minor_ {295} _axis_ of Jupiter's _orbit_, or of his _density_, or of _the angle of refraction_, or _the length of an undulation_ of red light, we assume certain theories; but inasmuch as the theories are now the inevitable interpretation of ascertained facts, we can have no better terms to designate the conceptions thus referred to. And hence the rule which we must follow is, not that our terms must involve no theory, but that they imply the theory only in that sense in which it is the interpretation of the facts.

For example, the term _polarization_ of light was objected to, as involving a theory. Perhaps the term was at first suggested by conceiving light to consist of particles having poles turned in a particular manner. But among intelligent speculators, the notion of polarization soon reduced itself to the simple conception of opposite properties in opposite positions, which is a bare statement of the fact: and the term being understood to have this meaning, is a perfectly good term, and indeed the best which we can imagine for designating what is intended.

I need hardly add the caution, that names involving theoretical views not in accordance with facts are to be rejected. The following instances exemplify both the positive and the negative application of this maxim.

The distinction of _primary_ and _secondary_ rocks in geology was founded upon a theory; namely, that those which do not contain any organic remains were first deposited, and afterwards, those which contain plants and animals. But this theory was insecure from the first. The difficulty of making the separation which it implied, led to the introduction of a class of _transition_ rocks. And the recent researches of geologists lead them to the conclusion, that those rocks which are termed _primary_, may be the newest, not the oldest, productions of nature.

In order to avoid this incongruity, other terms have been proposed as substitutes for these. Sir C. Lyell remarks[33\4], that granite, gneiss, and the like, form a class {296} which should be designated by a common name; which name should not be of chronological import. He proposes _hypogene_, signifying 'nether-formed;' and thus he adopts the theory that they have not assumed their present form and structure at the surface, but determines nothing of the period when they were produced.

[Note 33\4: _Princ. Geol._ iv. 386.]

These hypogene rocks, again, he divides into unstratified or _plutonic_, and altered stratified, or _metamorphic_; the latter term implying the hypothesis that the stratified rocks to which it is applied have been altered, by the effect of fire or otherwise, since they were deposited. That fossiliferous strata, in some cases at least, have undergone such a change, is demonstrable from facts[34\4].

[Note 34\4: _Elem. Geol._ p. 17.]

The modern nomenclature of chemistry implies the oxygen theory of chemistry. Hence it has sometimes been objected to. Thus Davy, in speaking of the Lavoisierian nomenclature, makes the following remarks, which, however plausible they may sound, will be found to be utterly erroneous[35\4]. 'Simplicity and precision ought to be the characteristics of a scientific nomenclature: words should signify _things_, or the _analogies_ of things, and not _opinions_. . . . A substance in one age supposed to be simple, in another is proved to be compound, and _vice versâ_. A theoretical nomenclature is liable to continual alterations: _oxygenated muriatic acid_ is as improper a term as _dephlogisticated marine acid_. Every school believes itself to be in the right: and if every school assumes to itself the liberty of altering the names of chemical substances in consequence of _new ideas_ of their composition, there can be no permanency in the language of the science; it must always be confused and uncertain. Bodies which are _similar_ to each other should always be classed together; and there is a presumption that their composition is _analogous_. _Metals_, _earths_, _alkalis_, are appropriate names for the bodies they represent, and independent of all speculation: whereas _oxides_, _sulphurets_, and _muriates_ are terms founded upon opinions of the composition of bodies, some of which have been already found erroneous. {297} The least dangerous mode of giving a systematic form to a language seems to be to signify the analogies of substances by some common sign affixed to the beginning or the termination of the word. Thus as the metals have been distinguished by a termination in _um_, as _aurum_, so their calciform or oxidated state might have been denoted by a termination in _a_, as _aura_: and no progress, however great, in the science could render it necessary that such a mode of appellation should be changed.'

[Note 35\4: _Elements of Chem. Phil._ p. 46.]

These remarks are founded upon distinctions which have no real existence. We cannot separate _things_ from their _properties_, nor can we consider their properties and analogies in any other way than by having _opinions_ about them. By contrasting _analogies_ with _opinions_, it might appear as if the author maintained that there were certain analogies about which there was no room for erroneous opinions. Yet the analogies of chemical compounds, are, in fact, those points which have been most the subject of difference of opinion, and on which the revolutions of theories have most changed men's views. As an example of analogies which are still recognized under alterations of theory, the writer gives the relation of a metal to its oxide or calciform state. But this analogy of metallic oxides, as Red Copper or Iron Ore, to Calx, or burnt lime, is very far from being self-evident;--so far indeed, that the recognition of the analogy was a great step in chemical _theory_. The terms which he quotes, _oxygenated muriatic acid_ (and the same may be said of _dephlogisticated marine acid_,) if improper, are so not because they involve theory, but because they involve false theory;--not because those who framed them did not endeavour to express analogies, but because they expressed analogies about which they were mistaken. Unconnected names, as _metals_, _earths_, _alkalis_, are good as the _basis_ of a systematic nomenclature, but they are not substitutes for such a nomenclature. A systematic nomenclature is an instrument of great utility and power, as the modern history of chemistry has shown. It would be highly unphilosophical to reject {298} the use of such an instrument, because, in the course of the revolutions of science, we may have to modify, or even to remodel it altogether. Its utility is not by that means destroyed. It has retained, transmitted, and enabled us to reason upon, the doctrines of the earlier theory, so far as they are true; and when this theory is absorbed into a more comprehensive one, (for this, and not its refutation, is the end of a theory _so far as_ it is true,) the nomenclature is easily translated into that which the new theory introduces. We have seen, in the history of astronomy, how valuable the theory of _epicycles_ was, in its time: the nomenclature of the relations of a planet's orbit, which that theory introduced, was one of Kepler's resources in discovering the _elliptical_ theory; and, though now superseded, is still readily intelligible to astronomers.

This is not the place to discuss the reasons for the _form_ of scientific terms; otherwise we might ask, in reference to the objections to the Lavoisierian nomenclature, if such forms as _aurum_ and _aura_ are good to represent the absence or presence of oxygen, why such forms as _sulphite_ and _sulphate_ are not equally good to represent the presence of what we may call a smaller or larger dose of oxygen, so long as the oxygen theory is admitted in its present form; and to indicate still the difference of the same substances, if under any change of theory it should come to be interpreted in a new manner.

But I do not now dwell upon such arguments, my object in this place being to show that terms involving theory are not only allowable, if understood so far as the theory is proved, but of great value, and indeed of indispensable use, in science. The objection to them is inconsistent with the objects of science. If, after all that has been done in chemistry or any other science, we have arrived at no solid knowledge, no permanent truth;--if all that we believe now may be proved to be false to-morrow;--then indeed our opinions and theories are corruptible elements, on which it would be unwise to rest any thing important, and which we might wish to exclude, even from our names. But if {299} our knowledge has no more security than this, we can find no reason why we should wish at all to have names of things, since the names are needed mainly that we may reason upon and increase our knowledge such as it is. If we are condemned to endless alternations of varying opinions, then, no doubt, our theoretical terms may be a source of confusion; but then, where would be the advantage of their being otherwise? what would be the value of words which should express in a more precise manner opinions equally fleeting? It will perhaps be said, our terms must express facts, not theories: but of this distinction so applied we have repeatedly shown the futility. Theories firmly established are facts. Is it not a fact that the rusting of iron arises from the metal combining with the oxygen of the atmosphere? Is it not a fact that a combination of oxygen and hydrogen produces water? That our terms should express _such_ facts, is precisely what we are here inculcating.

Our examination of the history of science has led us to a view very different from that which represents it as consisting in the succession of hostile opinions. It is, on the contrary, a progress, in which each step is recognized and employed in the succeeding one. Every theory, so far as it is true, (and all that have prevailed extensively and long, contain a large portion of truth,) is taken up into the theory which succeeds and seems to expel it. All the narrower inductions of the first are included in the more comprehensive generalizations of the second. And this is performed mainly by means of such terms as we are now considering;--terms involving the previous theory. It is by means of such terms, that the truths at first ascertained become so familiar and manageable, that they can be employed as elementary facts in the formation of higher inductions.

These principles must be applied also, though with great caution, and in a temperate manner, even to descriptive language. Thus the mode of describing the forms of crystals adopted by Werner and Romé de l'Isle was to consider an original form, from which other forms are derived by _truncations_ of the edges and the {300} angles. Haüy's method of describing the same forms, was to consider them as built up of rows of small solids, the angles being determined by the _decrements_ of these rows. Both these methods of description involve hypothetical views; and the last was intended to rest on a true physical theory of the constitution of crystals. Both hypotheses are doubtful or false: yet both these methods are good as modes of description: nor is Haüy's terminology vitiated, if we suppose (as in fact we must suppose in many instances,) that crystalline bodies are not really made up of such small solids. The mode of describing an octahedron of fluor spar, as derived from the cube, by decrements of one row on all the edges, would still be proper and useful as a description, whatever judgment we should form of the material structure of the body. But then, we must consider the solids which are thus introduced into the description as merely hypothetical geometrical forms, serving to determine the angles of the faces. It is in this way alone that Haüy's nomenclature can now be retained.

In like manner we may admit theoretical views into the descriptive phraseology of other parts of Natural History: and the theoretical terms will replace the obvious images, in proportion as the theory is generally accepted and familiarly applied. For example, in speaking of the Honeysuckle, we may say that the upper leaves are _perfoliate_, meaning that a single round leaf is perforated by the stalk, or threaded upon it. Here is an image which sufficiently conveys the notion of the form. But it is now generally recognized that this apparent single leaf is, in fact, two opposite leaves joined together at their bases. If this were doubted, it may be proved by comparing the upper leaves with the lower, which are really separate and opposite. Hence the term _connate_ is applied to these conjoined opposite leaves, implying that they grow together; or they are called _connato-perfoliate_. Again; formerly the corolla was called _monopetalous_ or _polypetalous_, as it consisted of one part or of several: but it is now agreed among botanists that those corollas which {301} appear to consist of a single part, are, in fact, composed of several soldered together; hence the term _gamopetalous_ is now employed (by De Candolle and his followers) instead of monopetalous[36\4].

[Note 36\4: On this subject, see Illiger, _Versuch einer Systematischen Vollständigen Terminologie für das Thierreich und Pflanzenreich_ (1810). De Candolle, _Théorie Élémentaire de la Botanique_.]

In this way the language of Natural History not only expresses, but inevitably implies, general laws of nature; and words are thus fitted to aid the progress of knowledge in this, as in other provinces of science.

APHORISM XII.

_If terms are systematically good, they are not to be rejected because they are etymologically inaccurate._

TERMS belonging to a system are defined, not by the meaning of their radical words, but by their place in the system. That they should be appropriate in their signification, aids the processes of introducing and remembering them, and should therefore be carefully attended to by those who invent and establish them; but this once done, no objections founded upon their etymological import are of any material weight. We find no inconvenience in the circumstance that _geometry_ means the measuring of the earth, that the name _porphyry_ is applied to many rocks which have no fiery spots, as the word implies, and _oolite_ to strata which have no roelike structure. In like manner, if the term _pœcilite_ were already generally received, as the name of a certain group of strata, it would be no valid ground for quarrelling with it, that this group was not always variegated in colour, or that other groups were equally variegated: although undoubtedly in _introducing_ such a term, care should be taken to make it as distinctive as possible. It often happens, as we have seen, that by the natural progress of changes in language, a word is steadily confirmed in a sense quite different from its etymological import. But though {302} we may accept such instances, we must not wantonly attempt to imitate them. I say, not wantonly: for if the progress of scientific identification compel us to follow any class of objects into circumstances where the derivation of the term is inapplicable, we may still consider the term as an unmeaning sound, or rather an historical symbol, expressing a certain member of our system. Thus if, in following the course of the _mountain_ or _carboniferous_ limestone, we find that in Ireland it does not form mountains nor contain coal, we should act unwisely in breaking down the nomenclature in which our systematic relations are already expressed, in order to gain, in a particular case, a propriety of language which has no scientific value.

All attempts to act upon the maxim opposite to this, and to make our scientific names properly descriptive of the objects, have failed and must fail. For the marks which really distinguish the natural classes of objects, are by no means obvious. The discovery of them is one of the most important steps in science; and when they are discovered, they are constantly liable to exceptions, because they do not contain the essential differences of the classes. The natural order _Umbellatæ_, in order to be a natural order, must contain some plants which have not umbels, as _Eryngium_[37\4]. 'In such cases,' said Linnæus, 'it is of small import what you call the order, if you take a proper series of plants, and give it some name which is clearly understood to apply to the plants you have associated.' 'I have,' he adds, 'followed the rule of borrowing the name _à fortiori_, from the principal feature.'

[Note 37\4: See _Hist. Ind. Sc._ b. xvi. c. iv. sect. 5.]

The distinction of crystals into systems according to the degree of symmetry which obtains in them, has been explained elsewhere. Two of these systems, of which the relation as to symmetry might be expressed by saying that one is _square pyramidal_ and the other _oblong pyramidal_, or the first _square prismatic_ and the second _oblong prismatic_, are termed by Mohs, the first, _Pyramidal_, and the second _Prismatic_. And it may {303} be doubted whether it is worth while to invent other terms, though these are thus defective in characteristic significance. As an example of a needless rejection of old terms in virtue of a supposed impropriety in their meaning, I may mention the attempt made in the last edition of Haüy's _Mineralogy_, to substitute _autopside_ and _heteropside_ for _metallic_ and _unmetallic_. It was supposed to be proved that all bodies have a metal for their basis; and hence it was wished to avoid the term _unmetallic_. But the words _metallic_ and _unmetallic_ may mean that minerals _seem_ metallic and unmetallic, just as well as if they contained the element _opside_ to imply this seeming. The old names express all that the new express, and with more simplicity, and therefore should not be disturbed.

The maxim on which we are now insisting, that we are not to be too scrupulous about the etymology of scientific terms, may, at first sight, appear to be at variance with our Fourth Aphorism, that words used technically are to retain their common meaning as far as possible. But it must be recollected, that in the Fourth Aphorism we spoke of _common_ words _appropriated_ as technical terms; we here speak of words _constructed_ for scientific purposes. And although it is, perhaps, impossible to draw a broad line between these two classes of terms, still the rule of propriety may be stated thus: In technical terms, deviations from the usual meaning of words are bad in proportion as the words are more familiar in our own language. Thus we may apply the term _Cirrus_ to a cloud composed of filaments, even if these filaments are straight; but to call such a cloud a _Curl cloud_ would be much more harsh.

Since the names of things, and of classes of things, when constructed so as to involve a description, are constantly liable to become bad, the natural classes shifting away from the descriptive marks thus prematurely and casually adopted, I venture to lay down the following maxim. {304}

APHORISM XIII.

_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\4], 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\4], '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.'

[Note 38\4: _Phil. Bot._ 241.]

[Note 39\4: _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\4]; 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_.

[Note 40\4: 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\4] 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.

[Note 41\4: b. xiii. c. 1.]

APHORISM XIV.

_The Binary Method of Nomenclature_ (_Names by Genus and Species_) _is the most convenient hitherto employed in Classification._

THE number of species in every province of Natural History is so vast that we cannot distinguish them and record the distinctions without some artifice. The known species of plants, for instance, were 10,000 in the time of Linnæus, and are now probably 60,000. It would be useless to endeavour to frame and employ separate names for each of these species.

The division of the objects into a subordinated system of classification enables us to introduce a Nomenclature which does not require this enormous number of names. The artifice employed is, to name a specimen by means of two (or it might be more) steps of the successive division. Thus in Botany, each of the Genera has its name, and the species are marked by the addition of some epithet to the name of the genus. In this manner about 1,700 Generic Names, with a moderate number of Specific Names, were found by Linnæus sufficient to designate with precision all the species of vegetables known at his time. And this _Binary Method_ of Nomenclature has been found so convenient, that it has been universally adopted in every other department of the Natural History of organized beings. {308}

Many other modes of Nomenclature have been tried, but no other has at all taken root. Linnæus himself appears at first to have intended marking each species by the Generic Name, accompanied by a characteristic Descriptive Phrase; and to have proposed the employment of a _Trivial_ Specific Name, as he termed it, only as a method of occasional convenience. The use of these trivial names, however, has become universal, as we have said; and is by many persons considered the greatest improvement introduced at the Linnæan reform.

APHORISM XV.

_The Maxims of Linnæus concerning the Names to be used in Botany_, (Philosophia Botanica, Nomina. Sections 210 to 255) _are good examples of Aphorisms on this subject._

BOTH Linnæus and other writers (as Adanson) have given many maxims with a view of regulating the selection of generic and specific names. The maxims of Linnæus were intended as much as possible to exclude barbarism and confusion, and have, upon the whole, been generally adopted.

These canons, and the sagacious modesty of great botanists, like Robert Brown, in conforming to them, have kept the majority of good botanists within salutary limits; though many of these canons were objected to by the contemporaries of Linnæus (Adanson and others[42\4]) as capricious and unnecessary restrictions.

[Note 42\4: Pref. cxxix. clxxii.]

Many of the names introduced by Linnæus certainly appear fanciful enough. Thus he gives the name _Bauhinia_ to a plant which has leaves in pairs, because the Bauhins were a pair of brothers. _Banisteria_ is the name of a climbing plant in honour of Banister, who travelled among mountains. But such names once established by adequate authority lose all their inconvenience and easily become permanent, and hence the reasonableness of one of the Linnæan rules[43\4]:-- That as such a perpetuation of the names of persons {309} by the names of plants is the only honour that botanists have to bestow, it ought to be used with care and caution, and religiously respected.

[Note 43\4: _Phil. Bot._ s. 239.]

[3rd ed. It may serve to show how sensitive botanists are to the allusions contained in such names, that it has been charged against Linnæus, as a proof of malignity towards Buffon, that he changed the name of the genus _Buffonia_, established by Sauvages, into _Bufonia_, which suggested a derivation from _Bufo_, a toad. It appears to be proved that the spelling was not Linnæus's doing.]

Another Linnæan maxim is (Art. 219), that the generic name must be fixed before we attempt to form a specific name; 'the latter without the former is like the clapper without the bell.'

The name of the genus being fixed, the species may be marked (Art. 257) by adding to it 'a single word taken at will from any quarter;' that is, it need not involve a description or any essential property of the plant, but may be a casual or arbitrary appellation. Thus the various species of _Hieracium_[44\4] are _Hieracium Alpinum_, _H. Halleri_, _H. Pilosella_, _H. dubium_, _H. murorum_, &c., where we see how different may be the kind of origin of the words.

[Note 44\4: Hooker, _Fl. Scot._ 228.]

Attempts have been made at various times to form the names of species from those of genera in some more symmetrical manner. But these have not been successful, nor are they likely to be so; and we shall venture to propound an axiom in condemnation of such names.

APHORISM XVI.

_Numerical names in Classification are bad; and the same may be said of other names of kinds, depending upon any fixed series of notes of order._

WITH regard to numerical names of kinds, of species for instance, the objections are of this nature. Besides that such names offer nothing for the imagination to take hold of, new discoveries will probably alter the {310} numeration, and make the names erroneous. Thus, if we call the species of a genus 1, 2, 3, a new species intermediate between 1 and 2, 2 and 3, &c. cannot be put in its place without damaging the numbers.

The geological term _Trias_, lately introduced to designate the group consisting of the _three_ members (Bunter Sandstein, Muschelkalk, and Keuper) becomes improper if, as some geologists hold, two of these members cannot be separated.

Objections resembling those which apply to numerical designations of species, apply to other cases of fixed series: for instance, when it has been proposed to mark the species by altering the termination of the genus. Thus Adanson[45\4], denoting a genus by the name _Fonna_ (_Lychnidea_), conceived he might mark five of its species by altering the last syllable, _Fonna_, _Fonna-e_, _Fonna-i_, _Fonna-o_, _Fonna-u_; then others by _Fonna-ba_, _Fonna-ka_, and so on. This would be liable to the same evils which have been noticed as belonging to the numerical method[46\4].

[Note 45\4: Pref. clxxvi.]