Chapter XXV: Introduction (1)

IT has been shown in the _History of the Sciences_, and has further appeared in the course of the _History of Ideas_, that almost every step in the progress of science is marked by the formation or appropriation of a technical term. Common language has, in most cases, a certain degree of looseness and ambiguity; as common knowledge has usually something of vagueness and indistinctness. In common cases too, knowledge usually does not occupy the intellect alone, but more or less interests some affection, or puts in action the fancy; and common language, accommodating itself to the office of expressing such knowledge, contains, in every sentence, a tinge of emotion or of imagination. But when our knowledge becomes perfectly exact and purely intellectual, we require a language which shall also be exact and intellectual;--which shall exclude alike vagueness and fancy, imperfection and superfluity;--in which each term shall convey a meaning steadily fixed and rigorously limited. Such a language that of science becomes, through the use of Technical Terms. And we must now endeavour to lay down some maxims and suggestions, by attention to which Technical Terms may be better fitted to answer their purpose. In order to do this, we shall in {258} the first place take a rapid survey of the manner in which Technical Terms have been employed from the earliest periods of scientific history.

The progress of the use of technical scientific language offers to our notice two different and successive periods; in the first of which, technical terms were formed casually, as convenience in each case prompted; while in the second period, technical language was constructed intentionally, with set purpose, with a regard to its connexion, and with a view of constructing a system. Though the casual and the systematic formation of technical terms cannot be separated by any precise date of time, (for at all periods some terms in some sciences have been framed unsystematically,) we may, as a general description, call the former the _Ancient_ and the latter the _Modern_ Period. In illustrating the two following Aphorisms, I will give examples of the course followed in each of these periods.

APHORISM I.

_In the Ancient Period of Sciences, Technical Terms were formed in three different ways:--by appropriating common words and fixing their meaning;--by constructing terms containing a description;--by constructing terms containing reference to a theory._

THE earliest sciences offer the earliest examples of technical terms. These are Geometry, Arithmetic, and Astronomy; to which we have soon after to add Harmonics, Mechanics, and Optics. In these sciences, we may notice the above-mentioned three different modes in which technical terms were formed.

I. The simplest and first mode of acquiring technical terms, is to take words current in common usage, and by rigorously defining or otherwise fixing their meaning, to fit them for the expression of scientific truths. In this manner almost all the fundamental technical terms of Geometry were formed. A _sphere_, a _cone_, a _cylinder_, had among the Greeks, at first, {259} meanings less precise than those which geometers gave to these words, and besides the mere designation of form, implied some use or application. A _sphere_ (σφαῖρα) was a hand-ball used in games; a _cone_ (κῶνος) was a boy's spinning-top, or the crest of a helmet; a _cylinder_ (κύλινδρος) was a roller; a _cube_ (κύβος) was a die: till these words were adopted by the geometers, and made to signify among them pure modifications of space. So an _angle_ (γωνία) was only a corner; a _point_ (σημεῖον) was a signal; a _line_ (γραμμὴ) was a mark; a _straight_ line (εὐθεῖα) was marked by an adjective which at first meant only _direct_. A _plane_ (ἐπίπεδον) is the neuter form of an adjective, which by its derivation means _on the ground_, and hence _flat_. In all these cases, the word adopted as a term of science has its sense rigorously fixed; and where the common use of the term is in any degree vague, its meaning may be modified at the same time that it is thus limited. Thus a _rhombus_ (ῥόμβος) by its derivation, might mean any figure which is _twisted_ out of a regular form; but it is confined by geometers to that figure which has four equal sides, its angles being oblique. In like manner, a _trapezium_ (τραπέζιον) originally signifies a _table_, and thus might denote any form; but as the tables of the Greeks had one side shorter than the opposite one, such a figure was at first called a _trapezium_. Afterwards the term was made to signify any figure with four unequal sides; a name being more needful in geometry for this kind of figure than for the original form.

This class of technical terms, namely, words adopted from common language, but rendered precise and determinate for purposes of science, may also be exemplified in other sciences. Thus, as was observed in the early portion of the history of astronomy[1\4], a _day_, a _month_, a _year_, described at first portions of time marked by familiar changes, but afterwards portions determined by rigorous mathematical definitions. The conception of the heavens as a revolving sphere, is so obvious, {260} that we may consider the terms which involve this conception as parts of common language; as the _pole_ (πόλος); the _arctic circle_, which includes the stars that never set[2\4]; the _horizon_ (ὁρίζων) a boundary, applied technically to the circle bounding the visible earth and sky. The _turnings of the sun_ (τροπαὶ ἠελίοιο), which are mentioned by Hesiod, gave occasion to the term _tropics_, the circles at which the sun in his annual motion turns back from his northward or southward advance. The _zones_ of the earth, (the _torrid_, _temperate_, and _frigid_;) the _gnomon_ of a dial; the _limb_ (or border) of the moon, or of a circular instrument, are terms of the same class. An _eclipse_ (ἔκλειψις) is originally a deficiency or disappearance, and joined with the name of the luminary, an _eclipse of the sun_ or _of the moon_, described the phenomenon; but when the term became technical, it sufficed, without addition, to designate the phenomenon.

[Note 1\4: _Hist. Ind. Sci._ b. iii. c. i.]

[Note 2\4: _Hist. Ast._ b. iii. c. i. sect. 8.]

In Mechanics, the Greeks gave a scientific precision to very few words: we may mention _weights_ (βάρεα), the _arms of a lever_ (μήχεα), its _fulcrum_ (ὑπομόχλιον), and the verb _to balance_ (ἰσσοῤῥοπεῖν). Other terms which they used, as _momentum_ (ῥοπὴ) and _force_ (δύναμις), did not acquire a distinct and definite meaning till the time of Galileo, or later. We may observe that all abstract terms, though in their scientific application expressing mere conceptions, were probably at first derived from some word describing external objects. Thus the Latin word for force, _vis_, seems to be connected with a Greek word, ἲς, or ϝὶς, which often has nearly the same meaning; but originally, as it would seem, signified a sinew or muscle, the obvious seat of animal strength.

In later times, the limitation imposed upon a word by its appropriation to scientific purposes, is often more marked than in the cases above described. Thus the _variation_ is made to mean, in astronomy, the second inequality of the moon's motion; in magnetism, the _variation_ signifies the angular deviation of the {261} compass-needle from the north; in pure mathematics, the _variation_ of a quantity is the formula which expresses the result of any small change of the most general kind. In like manner, _parallax_ (παράλλαξις) denotes a _change_ in general, but is used by astronomers to signify the change produced by the spectator's being removed from the center of the earth, his theoretical place, to the surface. _Alkali_ at first denoted the ashes of a particular plant, but afterwards, all bodies having a certain class of chemical properties; and, in like manner, _acid_, the class opposed to alkali, was modified in signification by chemists, so as to refer no longer to the taste.

Words thus borrowed from common language, and converted by scientific writers into technical terms, have some advantages and some disadvantages. They possess this great convenience, that they are understood after a very short explanation, and retained in the memory without effort. On the other hand, they lead to some inconvenience; for since they have a meaning in common language, a careless reader is prone to disregard the technical limitation of this meaning, and to attempt to collect their import in scientific books, in the same vague and conjectural manner in which he collects the purpose of words in common cases. Hence the language of science, when thus resembling common language, is liable to be employed with an absence of that scientific precision which alone gives it value. Popular writers and talkers, when they speak of _force_, _momentum_, _action and reaction_, and the like, often afford examples of the inaccuracy thus arising from the scientific appropriation of common terms.

II. Another class of technical terms, which we find occurring as soon as speculative science assumes a distinct shape, consists of those which are intentionally constructed by speculators, and which contain some description or indication distinctive of the conception to which they are applied. Such are a _parallelogram_ (παραλληλόγραμμον), which denotes a plane figure bounded by two pairs of parallel lines; a _parallelopiped_ {262} (παραλληλοπίπεδον), which signifies a solid figure bounded by three pairs of parallel planes. A _triangle_ (τρίγωνος, _trigon_) and a _quadrangle_ (τετράγωνος, _tetragon_) were perhaps words invented independently of the mathematicians: but such words extended to other cases, _pentagon_, _decagon_, _heccædecagon_, _polygon_, are inventions of scientific men. Such also are _tetrahedron_, _hexahedron_, _dodecahedron_, _tesseracontaoctohedron_, _polyhedron_, and the like. These words being constructed by speculative writers, explain themselves, or at least require only some conventional limitation, easily adopted. Thus _parallelogram_, might mean a figure bounded by any number of sets of parallel lines, but it is conventionally restricted to a figure of _four_ sides. So a _great circle_ in a sphere means one which passes through the center of the sphere; and a _small circle_ is any other. So in trigonometry, we have the hypotenuse (ὑποτενοῦσα), or _subtending_ line, to designate the line subtending an angle, and especially a right angle. In this branch of mathematics we have many invented technical terms; as _complement_, _supplement_, _cosine_, _cotangent_, a _spherical angle_, the _pole of a circle_, or of a sphere. The word _sine_ itself appears to belong to the class of terms already described as scientific appropriations of common terms, although its origin is somewhat obscure.

Mathematicians were naturally led to construct these and many other terms by the progress of their speculations. In like manner, when astronomy took the form of a speculative science, words were invented to denote distinctly the conceptions thus introduced. Thus the sun's annual path among the stars, in which not only solar, but also all lunar eclipses occur, was termed the _ecliptic_. The circle which the sun describes in his diurnal motion, when the days and nights are equal, the Greeks called the _equidiurnal_ (ἰσημερινὸς,) the Latin astronomers the _equinoctial_, and the corresponding circle on the earth was the _equator_. The ecliptic intersected the equinoctial in the _equinoctial points_. The _solstices_ (in Greek, τροπαὶ) were the times when the sun arrested his motion northwards or {263} southwards; and the _solstitial points_ (τὰ τροπικὰ σημεῖα) were the places, in the ecliptic where he then was. The name of _meridians_ was given to circles passing through the poles of the equator; the _solstitial colure_ (κόλουρος, curtailed), was one of these circles, which passes through the solstitial points, and is intercepted by the horizon.

We have borrowed from the Arabians various astronomical terms, as _Zenith_, _Nadir_, _Azimuth_, _Almacantar_. And these words, which among the Arabians probably belonged to the first class, of appropriated scientific terms, are for us examples of the second class, invented scientific terms; although they differ from most that we have mentioned, in not containing an etymology corresponding to their meaning in any language with which European cultivators of science are generally familiar. Indeed, the distinction of our two classes, though convenient, is in a great measure, casual. Thus most of the words we formerly mentioned, as _parallax_, _horizon_, _eclipse_, though appropriated technical terms among the Greeks, are to us invented technical terms.

In the construction of such terms as we are now considering, those languages have a great advantage which possess a power of forming words by composition. This was eminently the case with the Greek language; and hence most of the ancient terms of science in that language, when their origin is once explained, are clearly understood and easily retained. Of modern European languages, the German possesses the greatest facility of composition; and hence scientific authors in that language are able to invent terms which it is impossible to imitate in the other languages of Europe. Thus Weiss distinguishes his various systems of crystals as _zwei-und-zwei-gliedrig_, _ein-und-zwei-gliedrig_, _drey-und-drey-gliedrig,_ _&c._, (two-and-two-membered, one-and-two-membered, &c.) And Hessel, also a writer on crystallography, speaks of _doubly-one-membered edges_, _four-and-three spaced rays_, and the like.

How far the composition of words, in such cases, may be practised in the English language, and the general question, what are the best rules and artifices {264} in such cases, I shall afterwards consider. In the mean time, I may observe that this list of invented technical terms might easily be much enlarged. Thus in harmonics we have the various intervals, as a _Fourth_, a _Fifth_, an _Octave_, (_Diatessaron_, _Diapente_, _Diapason_,) a _Comma_, which is the difference of a _Major_ and _Minor Tone_; we have the various _Moods_ or _Keys_, and the notes of various lengths, as _Minims_, _Breves_, _Semibreves_, _Quavers_. In chemistry, _Gas_ was at first a technical term invented by Van Helmont, though it has now been almost adopted into common language. I omit many words which will perhaps suggest themselves to the reader, because they belong rather to the next class, which I now proceed to notice.

III. The third class of technical terms consists of such as are constructed by men of science, and involve some theoretical idea in the meaning which their derivation implies. They do not merely describe, like the class last spoken of, but describe with reference to some doctrine or hypothesis which is accepted as a portion of science. Thus _latitude_ and _longitude_, according to their origin, signify breadth and length; they are used, however, to denote measures of the distance of a place on the earth's surface from the equator, and from the first meridian, of which distances, one cannot be called _length_ more properly than the other. But this appropriation of these words may be explained by recollecting that the earth, as known to the ancient geographers, was much further extended from east to west than from north to south. The _Precession_ of the equinoxes is a term which implies that the stars are fixed, while the point which is the origin of the measure of celestial longitude moves backward. The _Right Ascension_ of a star is a measure of its position corresponding to terrestrial longitude; this quantity is identical with the angular ascent of the equinoctial point, when the star is in the horizon in a _right_ sphere; that is, a sphere which supposes the spectator to be at the equator. The _Oblique Ascension_ (a term now little used), is derived in like manner from an oblique sphere. The motion of a planet is _direct_ or _retrograde_, _in_ {265} _consequentia_ (_signa_), or _in antecedentia_, in reference to a certain assumed standard direction for celestial motions, namely, the direction opposite to that of the sun's daily motion, and agreeing with his annual motion among the stars; or with what is much more evident, the moon's monthly motion. The _equation of time_ is the quantity which must be added to or subtracted from the time marked by the sun, in order to reduce it to a theoretical condition of equable progress. In like manner the _equation of the center_ of the sun or of the moon is the angle which must be added to, or subtracted from, the actual advance of the luminary in the heavens, in order to make its motion equable. Besides the equation of the center of the moon, which represents the first and greatest of her deviations from equable motion, there are many other _equations_, by the application of which her motion is brought nearer and nearer to perfect uniformity. The second of these equations is called the _evection_, the third the _variation_, the fourth the _annual equation_, The motion of the sun as affected by its inequalities is called his _anomaly_, which term denotes inequality. In the History of Astronomy, we find that the inequable motions of the sun, moon, and planets were, in a great measure, reduced to rule and system by the Greeks, by the aid of an hypothesis of circles, revolving, and carrying in their motion other circles which also revolved. This hypothesis introduced many technical terms, as _deferent_, _epicycle_, _eccentric_. In like manner, the theories which have more recently taken the place of the theory of epicycles have introduced other technical terms, as the _elliptical orbit_, the _radius vector_, and the _equable description of areas_ by this radius, which phrases express the true laws of the planetary motions.

There is no subject on which theoretical views have been so long and so extensively prevalent as astronomy, and therefore no other science in which there are so many technical terms of the kind we are now considering. But in other subjects also, so far as theories have been established, they have been accompanied by the introduction or fixation of technical terms. Thus, as {266} we have seen in the examination of the foundations of mechanics, the terms _force_ and _inertia_ derive their precise meaning from a recognition of the first law of motion; _accelerating force_ and _composition of motion_ involve the second law; _moving force_, _momentum_, _action_ and _reaction_, are expressions which imply the third law. The term _vis viva_ was introduced to express a general property of moving bodies; and other terms have been introduced for like purposes, as _impetus_ by Smeaton, and _work done_, by other engineers. In the recent writings of several French engineers, the term _travail_ is much employed, to express the work done and the force which does it: this term has been rendered by _labouring force_. The proposition which was termed the _hydrostatic paradox_ had this name in reference to its violating a supposed law of the action of forces. The verb to _gravitate_, and the abstract term _gravitation_, sealed the establishment of Newton's theory of the solar system.

In some of the sciences, opinions, either false, or disguised in very fantastical imagery, have prevailed; and the terms which have been introduced during the reign of such opinions, bear the impress of the time. Thus in the days of alchemy, the substances with which the operator dealt were personified; and a metal when exhibited pure and free from all admixture was considered as a little king, and was hence called a _regulus_, a term not yet quite obsolete. In like manner, a substance from which nothing more of any value could be extracted, was dead, and was called a _caput mortuum_. Quick silver, that is, live silver (_argentum vivum_), was killed by certain admixtures, and was _revived_ when restored to its pure state.

We find a great number of medical terms which bear the mark of opinions formerly prevalent among physicians; and though these opinions hardly form a part of the progress of science, and were not presented in our History, we may notice some of these terms as examples of the mode in which words involve in their derivation obsolete opinions. Such words as _hysterics_, _hypochondriac_, _melancholy_, _cholera_, _colic_, _quinsey_ {267} (_squinantia_, συνάγχη, a suffocation), _megrim_, _migrane_ (_hemicranium_, the middle of the skull), _rickets_, (_rachitis_, from ῥάχις, the backbone), _palsy_, (_paralysis_, παράλυσις,) _apoplexy_ (ἀποπληξία, a stroke), _emrods_, (αἱμοῤῥοΐδες, _hemorrhoids_, a flux of blood), _imposthume_, (corrupted from _aposteme_, ἀπόστημα, an abscess), _phthisis_ (φθίσις, consumption), _tympanum_ (τυμπανία, swelling), _dropsy_ (_hydropsy_, ὕδρωψ,) _sciatica_, isciatica (ἰσκιαδικὴ, from ἰσκίον, the hip), _catarrh_ (κατάῤῥους, a flowing down), _diarrhœa_ (διαῤῥοία, a flowing through), _diabetes_ (διαβήτης, a passing through), _dysentery_ (δυσεντερία, a disorder of the entrails), _arthritic_ pains (from ἄρθρα, the joints), are names derived from the supposed or real seat and circumstances of the diseases. The word from which the first of the above names is derived (ὑστέρα, the last place,) signifies the womb, according to its order in a certain systematic enumeration of parts. The second word, _hypochondriac_, means something affecting the viscera below the cartilage of the breastbone, which cartilage is called χόνδρος; _melancholy_ and _cholera_ derive their names from supposed affections of χολὴ, the bile. _Colic_ is that which affects the _colon_ (κῶλον), the largest member of the bowels. A disorder of the eye is called _gutta serena_ (the 'drop serene' of Milton), in contradistinction to _gutta turbida_, in which the impediment to vision is perceptibly opake. Other terms also record the opinions of the ancient anatomists, as _duodenum_, a certain portion of the intestines, which they estimated as twelve inches long. We might add other allusions, as the _tendon of Achilles_.

Astrology also supplied a number of words founded upon fanciful opinions; but this study having been expelled from the list of sciences, such words now survive, only so far as they have found a place in common language. Thus men were termed _mercurial_, _martial_, _jovial_, or _saturnine_, accordingly as their characters were supposed to be determined by the influence of the planets, Mercury, Mars, Jupiter, or Saturn. Other expressions, such as _disastrous_, _ill-starred_, _exorbitant_, _lord of the ascendant_, and hence _ascendancy_, _influence_, {268} a _sphere of action_, and the like, may serve to show how extensively astrological opinions have affected language, though the doctrine is no longer a recognized science.

The preceding examples will make it manifest that opinions, even of a recondite and complex kind, are often implied in the derivation of words; and thus will show how scientific terms, framed by the cultivators of science, may involve received hypotheses and theories. When terms are thus constructed, they serve not only to convey with ease, but to preserve steadily and to diffuse widely, the opinions which they thus assume. Moreover, they enable the speculator to employ these complex conceptions, the creations of science, and the results of much labour and thought, as readily and familiarly as if they were convictions borrowed at once from the senses. They are thus powerful instruments in enabling philosophers to ascend from one step of induction and generalization to another; and hereby contribute powerfully to the advance of knowledge and truth.

It should be noticed, before we proceed, that the names of natural objects, when they come to be considered as the objects of a science, are selected according to the processes already enumerated. For the most part, the natural historian adopts the common names of animals, plants, minerals, gems, and the like, and only endeavours to secure their steady and consistent application. But many of these names imply some peculiar, often fanciful, belief respecting the object.

Various plants derive their names from their supposed virtues, as _herniaria_, _rupture-wort_; or from legends, as _herba Sancti Johannis_, _St. John's wort_. The same is the case with minerals: thus the _topaz_ was asserted to come from an island so shrouded in mists that navigators could only _conjecture_ (τοπάζειν) where it was. In these latter cases, however, the legend is often not the true origin of the name, but is suggested by it.

The privilege of constructing names where they are wanted, belongs to natural historians no less than to {269} the cultivators of physical science; yet in the ancient world, writers of the former class appear rarely to have exercised this privilege, even when they felt the imperfections of the current language. Thus Aristotle repeatedly mentions classes of animals which have no name, as co-ordinate with classes that have names; but he hardly ventures to propose names which may supply these defects[3\4]. The vast importance of nomenclature in natural history was not recognized till the modern period.

[Note 3\4: In his _History of Animals_, (b. i. c. vi.), he says, that the great classes of animals are Quadrupeds, Birds, Fishes, Whales (_Cetaceans_), Oysters (_Testaceans_), animals like crabs which have no general name (_Crustaceans_), soft animals (_Mollusks_ and _Insects_). He does, however, call the Crustaces by a name (_Malacostraca_, soft-shelled) which has since been adopted by Naturalists.]

We have, however, hitherto considered only the formation or appropriation of single terms in science; except so far as several terms may in some instances be connected by reference to a common theory. But when the value of technical terms began to be fully appreciated, philosophers proceeded to introduce them into their sciences more copiously and in a more systematic manner. In this way, the modern history of technical language has some features of a different aspect from the ancient; and must give rise to a separate Aphorism.

APHORISM II.

_In the Modern Period of Science, besides the three processes anciently employed in the formation of technical terms, there have been introduced Systematic Nomenclature, Systematic Terminology, and the Systematic Modification of Terms to express theoretical relations_[4\4].

[Note 4\4: On the subject of Terminology and Nomenclature, see also Aphorisms LXXXVIII and XCVIII concerning Ideas, and b. viii. c. ii. of the _History of Scientific Ideas_. In those places I have spoken of the distinction of _Terminology_ and _Nomenclature_.]

WRITERS upon science have gone on up to modern times forming such technical terms as they had occasion for, by the three processes above {270} described;--namely, appropriating and limiting words in common use;--constructing for themselves words descriptive of the conception which they wished to convey;--or framing terms which by their signification imply the adoption of a theory. Thus among the terms introduced by the study of the connexion between magnetism and electricity, the word _pole_ is an example of the first kind; the name of the subject, _electro-magnetism_, of the second; and the term _current_, involving an hypothesis of the motion of a fluid, is an instance of the third class. In chemistry, the term _salt_ was adopted from common language, and its meaning extended to denote any compound of a certain kind; the term _neutral_ salt implied the notion of a balanced opposition in the two elements of the compound; and such words as _subacid_ and _superacid_, invented on purpose, were introduced to indicate the cases in which this balance was not attained. Again, when the phlogistic theory of chemistry was established, the term _phlogiston_ was introduced to express the theory, and from this such terms as _phlogisticated_ and _dephlogisticated_ were derived, exclusively words of science. But in such instances as have just been given, we approach towards a systematic modification of terms, which is a peculiar process of modern times. Of this, modern chemistry forms a prominent example, which we shall soon consider, but we shall first notice the other processes mentioned in the Aphorism.

I. In ancient times, no attempt was made to invent or select a Nomenclature of the objects of Natural History which should be precise and permanent. The omission of this step by the ancient naturalists gave rise to enormous difficulty and loss of time when the sciences resumed their activity. We have seen in the history of the sciences of classification, and of botany in especial[5\4], that the early cultivators of that study in modern times endeavoured to identify all the plants described by Greek and Roman writers with those which grow in the north of Europe; and were involved {271} in endless confusion[6\4], by the multiplication of names of plants, at the same time superfluous and ambiguous. The _Synonymies_ which botanists (Bauhin and others) found it necessary to publish, were the evidences of these inconveniences. In consequence of the defectiveness of the ancient botanical nomenclature, we are even yet uncertain with respect to the identification of some of the most common trees mentioned by classical writers[7\4]. The ignorance of botanists respecting the importance of nomenclature operated in another manner to impede the progress of science. As a good nomenclature presupposes a good system of classification, so, on the other hand, a system of classification cannot become permanent without a corresponding nomenclature. Cæsalpinus, in the sixteenth century[8\4], published an excellent system of arrangement for plants; but this, not being connected with any system of names, was never extensively accepted, and soon fell into oblivion. The business of framing a scientific botanical classification was in this way delayed for about a century. In the same manner, Willoughby's classification of fishes, though, as Cuvier says, far better than any which preceded it, was never extensively adopted, in consequence of having no nomenclature connected with it.

[Note 5\4: _Hist. Ind. Sc._ b. xvi. c. ii.]

[Note 6\4: _Hist. Ind. Sc._ b. xvi. c. iii. sect. 3.]

[Note 7\4: For instance, whether the _fagus_ of the Latins be the beech or the chestnut.]

[Note 8\4: _Ib._ b. xvi. c. iii. sect. 2.]

II. Probably one main cause which so long retarded the work of fixing at the same time the arrangement and the names of plants, was the great number of minute and diversified particulars in the structure of each plant which such a process implied. The stalks, leaves, flowers, and fruits of vegetables, with their appendages, may vary in so many ways, that common language is quite insufficient to express clearly and precisely their resemblances and differences. Hence botany required not only a fixed system of _names_ of plants, but also an artificial system of phrases fitted to _describe_ their parts: not only a _Nomenclature_, but also {272} a _Terminology_. The Terminology was, in fact, an instrument indispensably requisite in giving fixity to the Nomenclature. The recognition of the kinds of plants must depend upon the exact comparison of their resemblances and differences; and to become a part of permanent science, this comparison must be recorded in words.

The formation of an exact descriptive language for botany was thus the first step in that systematic construction of the technical language of science, which is one of the main features in the intellectual history of modern times. The ancient botanists, as De Candolle[9\4] says, did not make any attempt to select terms of which the sense was rigorously determined; and each of them employed in his descriptions the words, metaphors, or periphrases which his own genius suggested. In the History of Botany[10\4], I have noticed some of the persons who contributed to this improvement. 'Clusius,' it is there stated, 'first taught botanists to describe well. He introduced exactitude, precision, neatness, elegance, method: he says nothing superfluous; he omits nothing necessary.' This task was further carried on by Jung and Ray[11\4]. In these authors we see the importance which began to be attached to the exact definition of descriptive terms; for example, Ray quotes Jung's definition of _Caulis_, a stalk.

[Note 9\4: _Theor. Elem. de Bot._ p. 327.]

[Note 10\4: _Hist. Ind. Sc._ b. xvi. c. iii. sect. 3.]

[Note 11\4: _Hist. Ind. Sc._ b. xvi. c. iii. sect. 3 (about A.D. 1660).]

The improvement of descriptive language, and the formation of schemes of classification of plants, went on gradually for some time, and was much advanced by Tournefort. But at last Linnæus embodied and followed out the convictions which had gradually been accumulating in the breasts of botanists; and by remodelling throughout both the terminology and the nomenclature of botany, produced one of the greatest reforms which ever took place in any science. He thus supplied a conspicuous example of such a reform, and a most admirable model of a language, from which {273} other sciences may gather great instruction. I shall not here give any account of the terms and words introduced by Linnæus. They have been exemplified in the _History of Science_[12\4]; and the principles which they involve I shall consider separately hereafter. I will only remind the reader that the great simplification in _nomenclature_ which was the result of his labours, consisted in designating each kind of plant by a _binary_ term consisting of the name of the _genus_ combined with that of the _species_: an artifice seemingly obvious, but more convenient in its results than could possibly have been anticipated.

[Note 12\4: _Ib._ c. iv. sect. 1-3.]

Since Linnæus, the progress of Botanical Anatomy and of Descriptive Botany have led to the rejection of several inexact expressions, and to the adoption of several new terms, especially in describing the structure of the fruit and the parts of cryptogamous plants. Hedwig, Medikus, Necker, Desvaux, Mirbel, and especially Gærtner, Link, and Richard, have proposed several useful innovations, in these as in other parts of the subject; but the general mass of the words now current consists still, and will probably continue to consist, of the terms established by the Swedish Botanist[13\4].

[Note 13\4: De Candolle, _Th. Elem._ p. 307.]

When it was seen that botany derived so great advantages from a systematic improvement of its language, it was natural that other sciences, and especially classificatory sciences, should endeavour to follow its example. This attempt was made in Mineralogy by Werner, and afterwards further pursued by Mohs. Werner's innovations in the descriptive language of Mineralogy were the result of great acuteness, an intimate acquaintance with minerals, and a most methodical spirit: and were in most respects great improvements upon previous practices. Yet the introduction of them into Mineralogy was far from regenerating that science, as Botany had been regenerated by the Linnæan reform. It would seem that the perpetual {274} scrupulous attention to most minute differences, (as of lustre, colour, fracture,) the greater part of which are not really important, fetters the mind, rather than disciplines it or arms it for generalization. Cuvier has remarked[14\4] that Werner, after his first _Essay on the Characters of Minerals_, wrote little; as if he had been afraid of using the system which he had created, and desirous of escaping from the chains which he had imposed upon others. And he justly adds, that Werner dwelt least, in his descriptions, upon that which is really the most important feature of all, the crystalline structure. This, which is truly a definite character, like those of Botany, does, when it can be clearly discerned, determine the place of the mineral in a system. This, therefore, is the character which, of all others, ought to be most carefully expressed by an appropriate language. This task, hardly begun by Werner, has since been fully executed by others, especially by Romé de l'Isle, Haüy, and Mohs. All the forms of crystals can be described in the most precise manner by the aid of the labours of these writers and their successors. But there is one circumstance well worthy our notice in these descriptions. It is found that the language in which they can best be conveyed is not that of words, but of _symbols_. The relations of space which are involved in the forms of crystalline bodies, though perfectly definite, are so complex and numerous, that they cannot be expressed, except in the language of mathematics: and thus we have an extensive and recondite branch of mathematical science, which is, in fact, only a part of the Terminology of the mineralogist.

[Note 14\4: _Éloges_, ii. 134.]

The Terminology of Mineralogy being thus reformed, an attempt was made to improve its Nomenclature also, by following the example of Botany. Professor Mohs was the proposer of this innovation. The names framed by him were, however, not composed of two but of three elements, designating respectively the Species, the Genus, and the Order[15\4]: thus he has such species as {275} _Rhombohedral Lime Haloide_, _Octahedral Fluor Haloide_, _Prismatic Hal Baryte_. These names have not been generally adopted; nor is it likely that any names constructed on such a scheme will find acceptance among mineralogists, till the higher divisions of the system are found to have some definite character. We see no real mineralogical significance in Mohs's Genera and Orders, and hence we do not expect them to retain a permanent place in the science.

[Note 15\4: _Hist. Ind. Sc._ b. xv. c. ix.]

The only systematic names which have hitherto been generally admitted in Mineralogy, are those expressing the chemical constitution of the substance; and these belong to a system of technical terms different from any we have yet spoken of, namely to terms formed by systematic modification.

III. The language of Chemistry was already, as we have seen, tending to assume a systematic character, even under the reign of the phlogiston theory. But when oxygen succeeded to the throne, it very fortunately happened that its supporters had the courage and the foresight to undertake a completely new and systematic recoinage of the terms belonging to the science. The new nomenclature was constructed upon a principle hitherto hardly applied in science, but eminently commodious and fertile; namely, the principle of indicating a modification of relations of elements, by a change in the termination of the word. Thus the new chemical school spoke of sulph_uric_ and sulph_urous_ acids; of sulph_ates_ and sulph_ites_ of bases; and of sulph_urets_ of metals; and in like manner, of phos_phoric_ and phos_phorous_ acids, of phos_phates_, phos_phites_, phos_phurets_. In this manner a nomenclature was produced, in which the very name of a substance indicated at once its constitution and place in the system.

The introduction of this chemical language can never cease to be considered one of the most important steps ever made in the improvement of technical terms; and as a signal instance of the advantages which may result from artifices apparently trivial, if employed in a manner conformable to the laws of phenomena, and systematically pursued. It was, however, proved that {276} this language, with all its merits, had some defects. The relations of elements in composition were discovered to be more numerous than the modes of expression which the terminations supplied. Besides the sulphurous and sulphuric acids, it appeared there were others; these were called the _hyposulphurous_ and _hyposulphuric_: but these names, though convenient, no longer implied, by their form, any definite relation. The compounds of Nitrogen and Oxygen are, in order, the _Protoxide_, the _Deutoxide_ or _Binoxide_; _Hyponitrous_ Acid, _Nitrous_ Acid, and _Nitric_ Acid. The nomenclature here ceases to be systematic. We have three oxides of Iron, of which we may call the first the _Protoxide_, but we cannot call the others the _Deutoxide_ and _Trioxide_, for by doing so we should convey a perfectly erroneous notion of the proportions of the elements. They are called the _Protoxide_, the _Black_ Oxide, and the _Peroxide_. We are here thrown back upon terms quite unconnected with the system.

Other defects in the nomenclature arose from errours in the theory; as for example the names of the muriatic, oxymuriatic, and hyperoxymuriatic acids; which, after the establishment of the new theory of chlorine, were changed to _hydrochloric_ acid, _chlorine_, and _chloric_ acid.

Thus the chemical system of nomenclature, founded upon the oxygen theory, while it shows how much may be effected by a good and consistent scheme of terms, framed according to the real relations of objects, proves also that such a scheme can hardly be permanent in its original form, but will almost inevitably become imperfect and anomalous, in consequence of the accumulation of new facts, and the introduction of new generalizations. Still, we may venture to say that such a scheme does not, on this account, become worthless; for it not only answers its purpose in the stage of scientific progress to which it belongs:--so far as it is not erroneous, or merely conventional, but really systematic and significant of truth, its terms can be translated at once into the language of any higher generalization which is afterwards arrived at. If terms express {277} relations really ascertained to be true, they can never lose their value by any change of the received theory. They are like coins of pure metal, which, even when carried into a country which does not recognize the sovereign whose impress they bear, are still gladly received, and may, by the addition of an explanatory mark, continue part of the common currency of the country.

These two great instances of the reform of scientific language, in Botany and in Chemistry, are much the most important and instructive events of this kind which the history of science offers. It is not necessary to pursue our historical survey further. Our remaining Aphorisms respecting the Language of Science will be collected and illustrated indiscriminately, from the precepts and the examples of preceding philosophers of all periods[16\4].

[Note 16\4: See at the end of these Aphorisms, further illustrations of them from the recent history of Comparative Anatomy and Chemistry.]

We may, however, remark that Aphorisms III., IV., V., VI., VII., respect peculiarly the Formation of Technical Terms by the Appropriation of Common Words, while the remaining ones apply to the Formation of New Terms.

It does not appear possible to lay down a system of rules which may determine and regulate the construction of all technical terms, on all the occasions on which the progress of science makes them necessary or convenient. But if we can collect a few maxims such as have already offered themselves to the minds of philosophers, or such as may be justified by the instances by which we shall illustrate them, these maxims may avail to guide us in doubtful cases, and to prevent our aiming at advantages which are unattainable, or being disturbed by seeming imperfections which are really no evils. I shall therefore state such maxims of this kind as seem most sound and useful. {278}

APHORISM III.

_In framing scientific terms, the appropriation of old words is preferable to the invention of new ones._

THIS maxim is stated by Bacon in his usual striking manner. After mentioning _Metaphysic_, as one of the divisions of Natural Philosophy, he adds[17\4]: 'Wherein I desire it may be conceived that I use the word _metaphysic_ in a different sense from that that is received: and in like manner I doubt not but it will easily appear to men of judgment that in this and other particulars, wheresoever my conception and notion may differ from the ancient, yet I am studious to keep the ancient terms. For, hoping well to deliver myself from mistaking by the order and perspicuous expressing of that I do propound; I am otherwise zealous and affectionate to recede as little from antiquity, either in terms or opinions, as may stand with truth, and the proficience of knowledge, . . . To me, that do desire, as much as lieth in my pen, to ground a sociable intercourse between antiquity and proficience, it seemeth best to keep a way with antiquity _usque ad aras_; and therefore to retain the ancient terms, though I sometimes alter the uses and definitions; according to the moderate proceeding in civil governments, when, although there be some alteration, yet that holdeth which Tacitus wisely noteth, _eadem magistratuum vocabula_.'

[Note 17\4: _De Augm._ lib. iii. c. iv.]

We have had before us a sufficient number of examples of scientific terms thus framed; for they formed the first of three classes which we described in the First Aphorism. And we may again remark, that science, when she thus adopts terms which are in common use, always limits and fixes their meaning in a technical manner. We may also repeat here the warning already given respecting terms of this kind, that they are peculiarly liable to mislead readers who {279} do not take care to understand them in their technical instead of their common signification. _Force_, _momentum_, _inertia_, _impetus_, _vis viva_, are terms which are very useful, if we rigorously bear in mind the import which belongs to each of them in the best treatises on Mechanics; but if the reader content himself with conjecturing their meaning from the context, his knowledge will be confused and worthless.

In the application of this Third Aphorism, other rules are to be attended to, which I add.

APHORISM IV.

_When common words are appropriated as technical terms, their meaning and relations in common use should be retained as far as can conveniently be done._

I WILL state an example in which this rule seems to be applicable. Mr Davies Gilbert[18\4] has recently proposed the term _efficiency_ to designate the work which a machine, according to the force exerted upon it, is capable of doing; the work being measured by the weight raised, and the space through which it is raised, jointly. The usual term employed among engineers for the work which a machine actually does, measured in the way just stated, is _duty_. But as there appears to be a little incongruity in calling that work _efficiency_ which the machine _ought_ to do, when we call that work _duty_ which it really does, I have proposed to term these two quantities _theoretical efficiency_ and _practical efficiency_, or _theoretical duty_ and _practical duty_[19\4].

[Note 18\4: _Phil. Trans._ 1827, p. 25.]

[Note 19\4: The term _travail_ is used by French engineers, to express _efficiency_ or _theoretical duty_. This term has been rendered in English by _labouring force_.]

Since common words are often vague in their meaning, I add as a necessary accompaniment to the Third Aphorism the following:-- {280}

APHORISM V.

_When common words are appropriated as technical terms, their meaning may be modified, and must be rigorously fixed._

THIS is stated by Bacon in the above extract: 'to retain the ancient terms, though I sometimes _alter the uses and definitions_.' The scientific use of the term is in all cases much more precise than the common use. The loose notions of _velocity_ and _force_ for instance, which are sufficient for the usual purposes of language, require to be fixed by exact measures when these are made terms in the science of Mechanics.

This scientific fixation of the meaning of words is to be looked upon as a matter of convention, although it is in reality often an inevitable result of the progress of science. _Momentum_ is conventionally defined to be the product of the numbers expressing the weight and the velocity; but then, it could be of no use in expressing the laws of motion if it were defined otherwise.

Hence it is no valid objection to a scientific term that the word in common language does not mean exactly the same as in its common use. It is no sufficient reason against the use of the term _acid_ for a class of bodies, that all the substances belonging to this class are not sour. We have seen that a _trapezium_ is used in geometry for any four-sided figure, though originally it meant a figure with two opposite sides parallel and the two others equal. A certain stratum which lies below the chalk is termed by English geologists _the green sand_. It has sometimes been objected to this denomination that the stratum has very frequently no tinge of green, and that it is often composed of lime with little or no sand. Yet the term is a good technical term in spite of these apparent improprieties; so long as it is carefully applied to that stratum which is geologically equivalent to the greenish sandy bed to which the appellation was originally applied.

When it appeared that _geometry_ would have to be employed as much at least about the heavens as the earth, Plato exclaimed against the folly of calling the {281} science by such a name; since the word signifies 'earth-measuring;' yet the word _geometry_ has retained its place and answered its purpose perfectly well up to the present day.

But though the meaning of the term may be modified or extended, it must be rigorously fixed when it is appropriated to science. This process is most abundantly exemplified by the terminology of Natural History, and especially of Botany, in which each term has a most precise meaning assigned to it. Thus Linnæus established exact distinctions between _fasciculus_, _capitulum_, _racemus_, _thyrsus_, _paniculus_, _spica_, _amentum_, _corymbus_, _umbella_, _cyma_, _verticillus_; or, in the language of English Botanists, _a tuft_, _a head_, _a cluster_, _a bunch_, _a panicle_, _a spike_, _a catkin_, _a corymb_, _an umbel_, _a cyme_, _a whorl_. And it has since been laid down as a rule[20\4], that each organ ought to have a separate and appropriate name; so that the term _leaf_, for instance, shall never be applied to _a leaflet_, _a bractea_, or _a sepal_ of the calyx.

[Note 20\4: De Candolle, _Theor. El._ 328.]

Botanists have not been content with fixing the meaning of their terms by verbal definition, but have also illustrated them by figures, which address the eye. Of these, as excellent modern examples, may be mentioned those which occur in the works of Mirbel[21\4], and Lindley[22\4].

[Note 21\4: _Élémens de Botanique_.]

[Note 22\4: _Elements of Botany_.]

APHORISM VI.

_When common words are appropriated as technical terms, this must be done so that they are not ambiguous in their application._

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\4] 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.

[Note 23\4: _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_.