Modern history



In the mid-nineteenth century the pursuit of scientific knowledge at last attained true autonomy and independence. Emerging as a consistent discipline with experiment and observation as its sanctions and mathematics as its logic, science extended its province far into space, and brought millions of years within the scope of its pronouncements. Emancipated from the limitations imposed by formal reasoning and dogmatic theology, an unquestionable force of certainty was claimed for scientific truths such as had never before been granted to any products of the intellect; and though only a small part of the swift advance in material civilisation that was made in this period can be directly attributed to contemporary progress in science, vast accretions of potential power were being built up. The formative period of modern science in which its character, its methods and its problems were established may be said to have ended about 1830; the modern age, with the technical ascendancy of science, to have begun about 1870. The interval is both classical, in that it contains the fulfilment of much that had been originated earlier, and transitional, because the beginning of recent science lies within it. Without abrupt discontinuity there was a remodelling of activity, a displacement of some guiding concepts of scientific thought by others. A single individual, like James Clerk Maxwell, might in one investigation add a coping-stone to the fabric of Newtonian celestial mechanics, while in another he helped to lay the foundations of the new theoretical physics. The doctrine of universal gravitation received its fullest vindication in 1845-6 from the discovery of the planet Neptune in accordance with theoretical predictions, when Newton’s optical theories had already been shaken by the newer theory of wave-motion. Even Darwinism, with its revolutionary impact upon biological studies, imposed not less but greater application to the problems which the older naturalists had sought to solve.

The increasing authority of science was reflected in a variety of ways and was not without consequence for the structure of the scientific movement itself. In the more advanced countries of Europe it was demanding more favourable attention within the educational system, above all in the universities. In Italy the academic standing of scientific research had never been wholly lost after the Renaissance; in Germany it was deliberately re-created after the defeat of Napoleon; France and Britain tardily followed the German example of reform. With the increasing ramification and complexity of research the scientific amateur changed insensibly into the professor, as large laboratories, expensive apparatus, and protracted labour became the concomitants of serious work. Laboratory training and instruction in research became normal features of higher scientific teaching. An exemplary institution, such as the chemical laboratory of Justus von Liebig at Giessen, was cited as a model by those who protested against the academic administration which paid insufficient tribute to the outstanding experimental talent of William Thomson or Claude Bernard. Inevitably the state was called upon to reform education and to provide financial support for a more generous organisation of science. As early as 1809 the Berlin Academy of Science had been incorporated in the university of that city; the new University of London, and the reforms in the older universities of England initiated after the Royal Commission of 1850, gave new scope for the teaching of scientific subjects; and Napoleon III was inspired by Pasteur to recognise the enhanced needs of science. With the state as patron and architect of new institutions the importance of the great national academies, founded in the seventeenth century, was correspondingly diminished. To some extent they were supplanted by another organisation, the scientific association. Of these the earliest were the German Scientific Association, founded by Lorenz Oken in 1822, and the British Association for the Advancement of Science, which met for the first time at York in 1831. The scientific association, besides being a response to the widespread interest in the more practical aspects of scientific knowledge in countries affected by the Industrial Revolution, was also intended to strengthen the scientific movement by placing it upon a broader basis of understanding and goodwill. About 1830, British science suffered from apathy and a sense of inferiority, and when, after the collapse of 1871, the like feeling prevailed in France, there too a National Association was brought into being.

The progress of science was still mainly in the hands of the four great nations of western Europe, each of them associated with one of the great conceptual achievements of the period—the theory of bacteria (France), thermodynamics (Germany), evolution (Britain) and molecular theory (Italy). Notable, but scattered, contributions came from eastern Europe, and the Academy of Science of St Petersburg kept the limited number of Russian savants in touch with the West. But beyond western Europe the most promising seat of scientific endeavour lay in the United States of America, whose universities were being gradually adapted to the German pattern, and were enriched by the growing number of young students who had profited by the experience which could only be obtained in European laboratories. The most celebrated American scientist of the period, Louis Agassiz of Harvard, was a Swiss emigre, but the first experiments on anaesthesia (1844), and Willard Gibbs’ theoretical work on thermodynamics thirty years later, were America’s gifts to Europe.

Here, too, there were changes in the foci of scientific interest. French science, in the time of Lavoisier, Laplace and Cuvier, had held an intellectual ascendancy which was lost after 1830. In the development of physics the empirical genius of Britain reappeared with fresh vigour, but still more remarkable were the consistently high level and fertility of German science. No branch of research was left unimproved by its efforts; German universities attracted men of all nations, and the German language became a major means of scientific communication, while Clausius, Helmholtz, Liebig or Ludwig by their theoretical investigations determined the course of their respective sciences.

Overcoming her initial backwardness, her lack of colonies and mercantile marine, Germany had by 1870 risen to the first rank of manufacturing countries, partly through her achievements in pure science and its technological application. Generally, however, the distance between laboratory and factory and field was still too great to permit effective co-operation between science and production. Since 1830 an increase of population, a greater facility for communication, and a larger volume of commerce had been brought about by many factors of which science was but one. Technical skill, such as the pioneers eulogised by Smiles possessed, had little relation to abstract scientific knowledge. The railway engineers, the ship-builders, and the machine-makers upon whom this new civilisation rested were men trained in the school of empiricism and experience, drawing indefinably from the steady accumulation of scientific knowledge since the seventeenth century. To the practical engineer who was now using accurate methods of survey to lay out a track, hydrodynamical researches to perfect the design of screw propellers, or the Bashforth electric chronograph for the improvement of artillery, science came as an aid rather than as a system. Though science was accelerating the rate of exploitation of inventions, it offered few directly, and even at the close of the period a new type of scientific inventor—Bessemer, Siemens, or Armstrong—was only beginning to impinge upon the basic industries. Precise control of operations by such means as accurate timing, pyrometry, and sampling was still a novelty. Waste from coke-ovens and gasworks, blast-furnaces and acid-towers polluted the neighbourhood of industrial centres and the economy of operation varied widely between one region and another. Conversely the scientific mind turned more naturally to the problems suggested in the logic of its own evolution than to those arising out of economic activity. Faraday’s metallurgical researches offer an unusual instance to the contrary, while later Pasteur’s life-work—the elimination of diseases afflicting the grape-vine, domestic animals, and man—had a directly utilitarian significance. Here there was a field of research in which the area of contact between science and craft was already broad. In others the organisation to enable industry to profit from scientific progress was inadequate, though it already existed in technical colleges, like the great French Ecole Polytechnique, mining schools and many private undertakings. In 1850 Prince Albert, echoing Bacon, could speak of science as discovering the laws of power, motion and transformation, by which the Almighty governs his creation, and of industry as applying them to the abundant raw materials which knowledge alone renders valuable; to a later generation the Great Exhibition of 1851 is conspicuous as the culmination of empirical technology. Science seems as yet to have entered only into the heavy-chemical industry (there were no synthetic manufactures), the preparation of a long list of vegetable products (including rubber and collodion), and the new arts of photography and electric telegraphy, to which the dynamo and arc-lamp may be added as curiosities. The displacement of coal and iron by oil and steel is not even hinted at in the manufactures of 1851.

Yet in a minor degree most aspects of life were revealing the influence of the scientific attitude by 1870. Better hygiene helped to reduce infant mortality and the incidence of epidemic disease; the outbreaks of cholera ravaging Europe from 1831 to as late as 1893 strikingly emphasised the socio-medical importance of clean water supplies and of rational sanitary legislation. Agricultural science had begun to filter into farming as the problem of soil fertility was taken up with some success. A few new ventures in commerce had sprung from scientific discoveries or owed their success directly to the adoption of scientific principles. The traditional chemical industries had been transformed by greater demands for alkalis, mineral acids and dyestuffs which only the use of novel processes and materials enabled them to satisfy. In addition new chemical preparations were gradually coming into use: artificial fertilisers, aniline dyes, nitro-explosives, chloroform, carbolic acid were the fruit of laboratory experiment, showing moreover, in the generally long interval between discovery and its useful application, the isolation in which research was still conducted. The synthetic-chemical industry, in which both Perkin, the discoverer of the first aniline dye, and Hofmann, his master (whom the Prince Consort had brought from Germany to teach the new organic chemistry) were engaged, from the first required scientific management. Disinterested research in organic chemistry had forged the links which bound these new manufactures to the gas-light industry which had been founded in the older empirical fashion at the opening of the century. Between 1830 and 1870 methods were worked out in the laboratory to give the coal-gas its highest luminous value, to remove impurities and utilise these by-products in other industries. Ammonia, with benzol and other ingredients of coaltar, was becoming an important article of commerce, but still, outside Germany, practice lagged far behind theory. The preparation of rubber, gutta-percha and hydraulic cement are other examples of manufactures which were recognised, in the 1851 Exhibition, as being of some importance, as a result of a combination of elementary science and technical skill. The electric-telegraph industry was born of the discoveries of Oersted and Faraday and was developed by scientists of distinction, like Wheatstone, Siemens and Thomson, who also possessed a strong practical talent. High technical ability was needed to overcome the difficulties that increased with the length of the wires, and to design the delicate instruments which, again, only scientific instrument-makers could manufacture. These firms, also, found their business expanding soon after the middle of the century, as the profitable uses for measuring and analytical equipment of all sorts were exploited—perhaps the surest indication of the incipient spread of science into industry. Where there was no strong technological tradition already entrenched, science was serving the needs of entrepreneurs who were far-sighted enough to appreciate its potentialities. Yet the opportunities to carry out the detailed investigations by which scientific principles are made to serve useful ends were still limited, though less severely in Germany than elsewhere.

Rationalisation in industry had begun. Rationalism in philosophy, with a distinct tendency to admire and emulate the works of science, is an older movement that may be traced back to Helvetius, Locke and Descartes. The current was widened and deepened by the nineteenth-century philosophers of the utilitarian school, Jeremy Bentham, the elder and the younger Mill. Rationalists were impressed by the success of mechanistic science in explaining the phenomena of nature (the natural philosophers had not generally been deflected thereby from the accepted canons of religion and morality), which they transmuted into such doctrines as the dependence of ideas upon the nature of sense-perceptions received, and, although most of the facts and illustrations that could usefully be drawn from exact science had already been absorbed before this period, the model of scientific reasoning was still before their eyes. The utilitarian, like the scientist, withdrew his attention from final causes in order to apply himself to immediate concerns—the nature of human behaviour and the derivation of the greatest benefits from social organisation. Bentham’s doctrine of utility, like Helvetius’ hedonism, demanded that the measure of efficiency be applied to the state and the individual. The question: how can society most efficiently ensure general and individual happiness? has a scientific ring. Significantly, the subject which the utilitarians themselves developed, political economy, was becoming known as a ‘science’; the mechanism of society was being subjected to the same type of precise (and, increasingly, mathematical) analysis that had triumphed in physical inquiries. Thus Malthus had stated his famous proposition in an exact numerical form (1798); he was not content merely to declare that populations tend to increase faster than their means of subsistence. And the student of the actual, rather than the ideal, state was naturally led to conclude that his own reflections, as well as the policies of those charged with government, could only be founded surely upon a discussion of a mass of facts concerning population, trade or justice collected with scientific rigour and detachment. The administration of the state was indeed not an art but a science. Of the influence of these doctrines on the business of government during the mid-nineteenth century, when they became a part of the general consciousness and the subject of political dispute, of the standard of efficiency as applied to law, finance and economic policy this is not the place to speak. If the changing structure of society was the deep cause of the changing character of government, political philosophies whose evolution had in turn been moulded by the influence of scientific thought suggested the forms which social pressure assumed.

Admiration for science as a purely intellectual fabric is made explicit in the positive philosophy of Auguste Comte, for whom the scientific was the only type of certain knowledge. For him physical science had risen to the third or positive state of learning, devoid of all theological and metaphysical complexion, in which understanding a phenomenon meant a knowledge of its relations to all other phenomena, under generalised laws. Comte urged the study of the history of science as revealing the progress of the sole true learning in comparison with which the history of philosophy was but a record of man’s dreams and aberrations. His conception, grandly organic, assembled all intellectual achievement into a single corpus of knowledge of an ascending order of complexity, the laws of the more complex sciences resting upon the laws of the less, from the most general and abstract theorems of mathematics to biology and finally the study of human society. His own endeavour was to elevate sociology to the positive state, to educe the laws of human behaviour with their verification in history and psychology, and to make an exact science of the natural history of man by the use of those methods which had been defined in physical science. And for J. S. Mill, as for Comte, the application of this perfected system of thought and investigation to philosophy or ‘moral science’ was not prohibited by the very different character of its problems and ends. ‘The proper study of mankind’ might become positive, propounding universal and demonstrative truth, if ‘the same process through which the laws of many simpler phenomena have by general acknowledgment been placed beyond dispute,... be consciously and deliberately applied to those more difficult enquiries.’ Following Comte in striking out a new course in sociology, parallel to that upon which he believed the physical sciences to be already definitively entered, Mill sought to draw the broad lines of a scientific deductive logic in moral and social thinking.

Within the positivist philosophy, Comte, the author of a religion of humanity in which material benefactors replaced the hierarchy of saints, emphasised the moral element in human life. Other minds looked to a happier future ushered in by technological versatility and mechanical social adjustments. Evolution, in society as in science, was the dominant concept of the latter part of the period. Liberals eagerly sought to accelerate the progress they believed to be inevitable. Socialism also developed an evolutionary interpretation of the broad course of history. In its earliest stages socialism had an idealist adumbration inherited from the French Revolution, but in the hands of Marx and Engels, despite the legacy of Hegel, it became the most extreme of rationalist doctrines. The weight of science (or rather, positivism) in Marxist philosophy is best seen in the particular theses by which the general dialectic was supported. In Das Kapital Marx deduced laws that had determined the development of the existing economic order, and would equally bring about its dissolution. In the economic interpretation of history—very different from the rigorous historiography that another facet of the influence of science was helping to create—similar laws are given a wider range, while Engels utilised recent anthropological findings to buttress the socialist theory of the archaic evolution of society from its primitive institution, the family. In human affairs Marx’s deterministic laws resembled Newton’s laws of motion; if they were correct they admitted no intervention of chance or genius. Laplace had boasted that given the mass and motion of the particles in the universe, its destiny was infinitely calculable; in the same spirit Marx maintained that in the ownership of the means of production the whole history and structure of a society, even to its arts and sciences, was determined. Mechanistic sociology had followed upon mechanistic science.

While philosophers were interpreting the astonishing triumphs of science in their various ways, the organic growth of natural knowledge was continuing, its stages not always confirming the assertions of those who tried to extract the quintessence of scientific thought for use in other disciplines. Fundamental assumptions were called in question, and the tendency was towards less rather than greater determinism. The complexity of nature belied the more dogmatic utterances of an earlier period. The unforeseen importance of an unconsidered dimension—time—began to work upon the structure of both physical and biological theory, giving the latter especially renewed interest and power. The interdependence of the various branches of science (accurately discerned by Comte) became yearly more evident, the effect being to increase rather than lessen the fragmentation of research. Studies on the frontiers between the sciences, in theoretical physics, physical chemistry and biochemistry, were more intensively cultivated, and helped to strengthen the internal consistency of science by causing the same concepts (such as those of thermodynamics, or atomism) to prevail in all or many of its branches.

The further exploitation of mathematical analysis was a prime instance of this process. Pure mathematics developed its modern character in this period. While existing modes of mathematical thought were extended—masters of an earlier age (Cauchy in France, Gauss in Germany) remaining active to the ’fifties—not less importance attaches to profound innovations. Hamilton of Dublin laid the foundations of the theory of operators and vectors; the Russian Lobatchevsky, the two Bolyais in Hungary, and the German Riemann initiated the study of geometries based upon non-Euclidean postulates; Hamilton, Grassmann, and Boole were pioneers of non-commutative algebras. The last-named, in the Laws of Thought (1854), has a claim to be the father of modern symbolic logic. These were all heterodox offshoots from the main stem of mathematics, comparatively little regarded, and apparently of the most highly speculative nature. Yet it was to this type of mathematics that theoretical physics returned at the end of the century. Meanwhile contemporary physics was bringing mathematical analysis from the branches such as mechanics and optics in which it was already established to the study of gases and electricity. A vital movement of research from the macrophysical problems of celestial mechanics to the microphysical problems of the structure of matter required a new type of mathematical equipment which was created by the use of statistical methods put into exact form in Gauss’s work on probability (c. 1800). For instance, in the investigations of Maxwell, Boltzmann and others into the kinetic theory of gases, it was not possible to observe or calculate the motion of a single molecule, but by means of complex statistical calculations it was possible for its probable motion to be inferred from the known properties of the mass. The non-physical sciences partly owed their emergence from a purely descriptive stage to the adoption of similar procedures. Mendel’s interpretation of his experiments on the hybridisation of plants (published in 1869, but ignored till 1900), which established the primary laws of genetics, is of a truly statistical type though the mathematics involved are elementary; and so, less precisely, is Darwin’s hypothesis of natural selection.

Before considering the progress of theoretical physics it is necessary to mention the empirical discoveries. Michael Faraday stands out in the nineteenth century as an experimenter of unsurpassed genius. Following-up Oersted’s observation (1820) of the magnetic field surrounding a conductor, Faraday at last obtained the converse effect in 1831, when he detected the changing electro-motive force in a conductor lying across a changing magnetic field. After this the other leading phenomena of induction were rapidly revealed and his fame was assured. By 1850 the bases of electrical science were secure; new concepts such as potential, dielectric capacity and resistance were firmly defined in spite of the lack of delicate instruments and metrology which continued until long after Faraday’s death in 1867. Much of this painstaking investigation was pursued in Germany, and is immortally linked with the name of Ohm. Of the industrially useful properties of electricity, heating and electrolysis had been known since the beginning of the century. The intraconversion of electrical and mechanical energy had been demonstrated. With this the electric telegraph, long projected, became a practical proposition, taken up rapidly by the railways before 1850, and soon made available for public use. In 1858 the first abortive transatlantic link was attempted. Since an efficient design of electric motor and generator could not spring at once from first principles, the consumption of electric power was still tiny in 1870. The distributive and other technical merits of electricity in industry were not obvious, and to many, including Joule of Manchester, whose experiments (1840-50) gave the quantitative relations between electrical and other forms of energy, heat-engines seemed considerably more economic.

The theoretical interpretation of the empirical work in electricity was of the first importance both in the purest scientific sense and in the applications which in turn flowed from it. Faraday was no great mathematician; instead he framed a vivid imagery of the play of electro-magnetic forces. His picture demanded an ether, an elastic medium of transmission in which the Tines of force’ became lines of strain. Although etherial hypotheses were very old, physicists had tended to gloss over the problem of the action of a force (such as gravity) at a distance across empty space, about which Newton himself had been discreetly silent. It was revived more acutely (about 1820) by the victory of the wave theory of light, for a vacuum could not be supposed to undulate. Faraday’s ether seemed, however, unable to submit to the quantitative treatment that was necessary, or to yield the comprehensive generalisations embracing the phenomena of magnetism, electricity and light that were sought. More conventional mathematical hypotheses also failed. At last, starting from Faraday’s ideas and admitting to the Royal Society that Faraday’s theory was ‘the same in structure as that which I have begun to develop’, Clerk Maxwell demonstrated mathematically in papers published between 1864 and 1868 that as a line of force spreads outwards from a centre of disturbance it travels as an electromagnetic wave, with the electric and magnetic components at right angles as they are in a conductor, having a velocity equal to that of light. Maxwell concluded that light is in fact such an electro-magnetic wave, so that a single ether with a given set of properties could in his equations be used to account for the propagation of all such forces. Certain consequences followed from the theory which could be, and were, experimentally verified; finally in 1887 Herz detected the electro-magnetic waves created by a spark-discharge.

The study of radiations was becoming an established department of physics as the physical similarity of the causes of the physiological sensations of light and heat was worked out. Radiations outside the visible spectrum could be brought under the scope of Maxwell’s theory. Faraday and others were experimenting on discharges within vacuum-tubes at high potentials—the first step to atomic physics. But the main advance in this period was towards the perfection of spectrum analysis. The primary observation that incandescent elements emit characteristic bright lines in their spectra was about a century old when the researches of Bunsen and Kirchhoff (c. 1855) gave to spectroscopy a firm position in analytical technique. Somewhat grander possibilities were disclosed by Foucault’s identification (1849) of some of the bright lines in the spectra of elements with the Fraunhofer dark lines in the spectrum of the sun. The coincidence of these lines was accounted for a decade later by Kirchhoff and others in an hypothesis derived from thermodynamical reasoning (since confirmed by electron theory) showing that light of the appropriate frequencies was absorbed by elements present in the sun’s periphery. As in the laboratory the spectroscope took its place beside the balance, so in the observatory it became an indispensable instrument of precision, second in importance in modem times to the giant reflecting telescope of which the prototype, with a 72-inch metallic mirror, was set up by Lord Rosse at Parsons-town, Ireland, in 1845. Spectroscopy revealed the composition of many stars as well as that of the sun, their temperature and their proper motions. The big telescope and its adjuncts brought in a new astronomy whose exponents became increasingly confident in their own opinions on the past and future of the universe. Astrophysics faced, cosmically, the same questions about the nature and history of matter which were becoming the most important subjects of physical inquiry.

In this, and other ways to be mentioned later, science was led to declare its own universal chronology. Whatever the hypothesis, whether it was assumed that the cosmos had been wound up in some great act of creation, or had evolved mechanistically in accordance with one of the possible variants of the nebula hypothesis, it seemed certain that it was not static, but was undergoing a steady process of equipartition of energy which must end in a motionless state of uniform temperature. Ultimate stagnation was stated by Thomson to be an inevitable consequence of the operation of thermodynamical laws as early as 1852; it was a doctrine that religious beliefs might rather suggest than oppose. The physical time-scale as then calculated (notably, in ignorance of radio-active phenomena) was far too brief to accommodate the vast epochs of slow transformation of species which evolutionary biology required, and which the geologists also were not disposed to deny, and these differences remained in dispute.

But by whatever means the duration of the solar system was computed, the attempt is important for its recognition of a limit in science, the irreversibility of a one-way process. Other limits imposed by the pattern of nature and not by logical or experimental inadequacies were being discovered, the first to be clearly apprehended being absolute zero, the ultimate degree of cold (1848). Of wider significance was the limitation or conservation of energy.

The term ‘energy’ has already been used in contexts where it is strictly anachronistic, since the exactly defined concept was unknown before 1851. At the beginning of the period the physics of heat was in confusion, for conventional opinion, including that of the strong French school, favoured the material theory which considered heat as an impalpable fluid flowing down temperature gradients; the kinetic theory, whose clearest evidence was the unlimited quantity of heat produced by mechanical friction, had failed to command general assent. The issues were hard fought in the decade 1840-50, which saw the complete triumph of thermodynamics. The development of the principle of the conservation of energy must be distinguished from that of the general kinetic theory. In 1824 a French engineer, Sadi Carnot, had examined the efficiency with which motive power could be obtained from a source of heat, taking as his example a perfect heat-engine in which work is done by the expansion and contraction of a gas without loss. By proving that otherwise a finite quantity of heat can be made to do infinite work, Carnot showed that the ‘motive power’ obtainable from heat is independent of all considerations save the difference in temperature of the two bodies between which heat is transferred—for example the boiler and condenser of a steam-engine. Carnot’s principle did not commit him to the kinetic theory, which, however, he expressed in unpublished notes of 1830, and it became better known in a material form. The material theory failed to explain how work was done by an expanding gas; the kinetic theory could not be established till it had been demonstrated that the heat lost by the gas was not latent but had been converted into mechanical energy. The conversion of energy at constant equivalencies was investigated experimentally by Mayer (1842) and Joule (from 1843): after the first complete and satisfactory account of thermodynamics due to Helmholtz (1847), Clausius, Rankine and Thomson elaborated the framework of mathematical equations, which were firmly embodied in physical science. The two so-called Laws of Thermodynamics are really derivable from Carnot’s principle (and indeed from the reductio ad absurdum of perpetual motion): the energy within a closed system is constant and becomes unavailable when the system reaches equilibrium, and it cannot be conserved by any means of reversing the natural flow of heat from a hot body to a cold.

Thermodynamics was partly called into existence by the study of the working steam-engine, but the science had hardly begun to have a return effect upon technology before the end of the period. It is interesting also that despite this link, much was owing to two Germans who were primarily physiologists, Mayer and Helmholtz. A new theory of energy was in the general consciousness, and was necessary to the progress of several departments of science. Even so, the pioneers of thermodynamics were granted but cursory attention before 1847; indifference was probably due partly to logical difficulties arising from the strange general concept of energy (for which no name then existed in the vocabulary of science) and the confusion between the two theories of heat, partly also to the technical delicacy of experiments to demonstrate precise equivalence. But by 1870 physics had been transformed into a unitary science, the study of a single dynamism in nature in which the phenomena of mechanics, electricity, heat and light were parallel manifestations of a single duality, matter and energy. If the universe was a closed system—and such was the assumption—then the general deduction of a single irreversible sequence and of a final state in which the processes of nature would cease through the equipartition of energy was inevitable. Physics seemed able to foretell the doom of creation.

Through thermodynamics (soon applied to the study of chemical reactions), electro-chemistry and other points of contact the physical or kinetic and the chemical or atomistic investigations of nature were brought to meet and gradually amalgamate. The revival of atomic theory by Dalton (1808) in a quantitative form had no immediate influence upon physics and even at the opening of this period many chemists doubted whether it was more than a convenient fiction. The mathematical physicist was gradually induced to take a particulate view of matter in treating (for instance) the properties of a gas in accordance with the empirical laws of Boyle and Charles, and thermodynamical ideas also prompted a return to Bernoulli’s early kinetic theory of gases (1738). In the following decade experimental investigations substantiated it further. Statistical methods in mathematics provided a suitable technique for theoretical study, and predictions based upon the theory were found to be confirmed. By 1862 ‘the theory of gases being little bodies flying about’, as Maxwell described it, had been raised at least to the level of a probable hypothesis by his own labours and those of Helmholtz and Clausius. But a unification of physical and chemical atomic theory, necessary for the full validity of either, was still prevented by the fact that certain constants, which could be determined independently by physical and chemical methods, showed a puzzling discordance. This was removed only when, after 1860, chemists accepted the force of Avogadro’s molecular hypothesis. Since 1845 attempts, little regarded, had been made to calculate the probable velocities and masses of the individual ‘atoms’ (really molecules) of gases. Events between 1860 and 1870 made it certain that during the next period of science the main task of chemistry would be to penetrate the mechanisms by which the fundamental particles are linked into molecules, which are the units of compound substances, while physics would be occupied in an examination of their properties and behaviour.

The consolidation of atomic theory had been the chief concern of inorganic chemists since 1830, by which time the list of common elements was complete. Analytical chemistry was already sufficiently advanced, and being steadily refined, so that it was normally possible to determine the proportions of the elements in a compound; the problem was to discover what these proportions signified in terms of relative numbers of atoms, and this required a knowledge of their relative weights. Moreover it was soon realised that all the atoms of one element in a compound are not necessarily included in a single group, but may be divided among two or more having independent linkages with the other elements in the combination, and therefore the pattern of the linkages became important. As Dalton’s theory conceived of the atom as the normal free unit of matter, experimental results became conflicting when elements were investigated in the gaseous state and in combination, since the particles of most gases are not atoms, but molecules; and Dalton had been unable to suggest any reliable means of ascertaining whether combinations of atoms were simple (one-to-one) or complex (one-to-two; two-to-two, etc.). Amidst these difficulties the work of measuring atomic weights and ascribing atomic formulae resembled a complicated piece of cryptography which could command slight confidence. However, the Swedish chemist Berzelius compiled a table of atomic weights which compares tolerably with those now accepted; he also introduced the symbolism of modern chemistry and derived correctly the formulae of many of the simpler organic compounds. He gave currency to an electro-chemical hypothesis which shows the influence of contemporary physics, supposing that the atoms of each element (and atomic groups, or radicals) were endowed with a characteristic charge, so that their affinities were a result of differences in polarity. But the methods in use were devious and depended largely on making analogies with the simplest compounds. Many chemists regarded the whole matter of atomic weights as speculative, and distrusted the use of numerical formulae which varied according to the opinions of the user. Even towards the middle of the century it was by no means certain that the whole atomic theory would not collapse under the weight of its own inconsistencies.

The confusion was naturally greatest with respect to the more complex organic compounds in which the molecules are composed of many atoms of different elements. Early organic analyses had been made by Lavoisier, and Dalton had attempted some application of his theory to organic substances. It was recognised that they consist very largely of the four elements carbon, hydrogen, nitrogen and oxygen; methods of estimating the proportions of the elements in combination were improved by Berzelius and Liebig, the phenomena of isomorphism and isomerism were known. As the molecules of the three gases are bi-atomic, the atomic weights in use varied by a factor of two (C = 6 or 12; O = 8 or 16). Electrochemical dualism imposed a somewhat arbitrary pattern on the notions of the processes by which more complex compounds are synthesised in the laboratory from the less. While theory was in doubt, empirical work proceeded. The first great triumph was Wohler’s synthesis of urea, an excretory product, in 1828. This seemed a trenchant blow against the vitalist belief that biological substances could never be artificially prepared. More interesting from the point of view of theory were the chains of compounds discovered during the next ten years in which a stable radical served as a peg to which other atoms or groups could be attached. A pattern was emerging; it seemed that ‘in inorganic chemistry the radicals are simple; in organic chemistry they are compounds, that is the sole difference’ (Dumas and Liebig, 1837). The number of preparations synthesised was growing enormously; some were to prove useful.

Within the next twenty years the growing mass of detailed research outgrew the generalisations which chemical theory was capable of framing. Dualism and the simple radical theory proved inadequate; elaborations of the latter, due on the one hand to the French school (Dumas, Gerhardt, Laurent), and to the German (Liebig, Wohler, Wurtz, Hofmann), with which English organic chemistry was closely allied, on the other, were inconclusively argued. Through the perplexing alternations of the theory of combination and the confusion of atomic weights it is possible to see that the problems at issue—the pattern of atomic structure within the molecule, and the reasons why certain arrangements only are possible or stable—were being visualised with greater clearness. The theory of valency, originated by the English chemist Frankland in 1852 and largely perfected by Kekule, a German who worked for a time in London, had by 1865 classified the elements numerically according to their combining-powers, that is, according to the number of hydrogen atoms with which an atom of the element enters into combination. In that year Kekule also gave the famous ring-formula for benzene, showing the multiple bonds between the six carbon and the six hydrogen atoms within the molecule. This first step in ‘molecular architecture’ was soon extended to other so-called ‘aromatic’ compounds.

Valency offered another useful criterion for the determination of atomic weights. At the Karlsruhe Conference (1860), summoned to resolve the doubts still obscuring this fundamental of chemical theory, it had been impossible to reach a satisfactory convention; but the Italian Canizzaro had revived with new force the molecular hypothesis of his countryman Avogadro, which was further promulgated by Meyer in an important work of 1864. With the concept of the molecule, not the atom, as the least free particle of matter discrepancies were removed and atomic theory was placed upon a secure quantitative foundation. The atomic weights derived by inorganic methods could now be reconciled with those that the organic chemist had accepted, and, as already mentioned, chemical atomism was by the same adjustment brought to agree with the kinetic theory of physics.

The first three-dimensional molecular patterns, worked out by Le Bel and van t’Hoff, fall just outside this period, though their history begins in 1848 with Pasteur’s discovery of optical isomers, two substances of identical composition but with different properties and forming crystals which are mirror-images of each other. Pasteur had already attributed this phenomenon to an asymmetry of atomic arrangement. The notion of spatial chemistry was not sympathetically received, and endeavour to discern some logical order in the table of the elements also awaited its full vindication after 1870. Early attempts to correlate properties and atomic weights inspired by some obvious family likenesses, such as that of New-lands in 1865, were treated with contempt. The reasoned and demonstrative statements of the periodic law made by Mendeleef and Meyer (1869-71) subdued scepticism, which was finally overcome through the isolation of the elements whose existence Mendeleef had predicted. Theoretical explanation of the law was awaited for more than a generation, and came from the development of atomic physics. As these last instances suggest, pragmatism was strong among even the chemical theorists of the time. This was only in part due to a healthy reluctance to frame hypotheses, for numerous ‘laws’ and ‘types’ of combination were announced and rejected, arising rather from an excessive preoccupation with the synthetic aspect of chemical technique. Organic chemistry had become the largest and most important branch of the science, but while organic chemists were acquiring greater operative powers for transforming substances and constructing molecules, they were in danger of losing sight of the fundamental study of matter which was the intellectual justification of their work.

The new artifices of organic chemistry were already affecting society in their applications to medicine, manufacture and war. The raw materials of the old chemical industry had been salt, alum, vitriols, and a great variety of vegetables used in the preparation of dyes and drugs. From wood, coal, nitrates and sulphur organic chemistry fabricated a variety of natural and artificial products. Although some large industries such as tanning and pottery-making continued their traditional processes untouched by science, techniques borrowed from chemistry were becoming more usual. Electrolysis, from which the plating industries grew up, had been discovered by Davy in 1807; catalysis, which has effected economies by speeding industrial reactions, by Berzelius in 1836. With the theory of radicals the modem pattern of laboratory synthesis and commercial exploitation begins to emerge, though the earlier workers were comparatively little interested in the useful properties of the many thousands of substances they examined. Delays in application were due less to this factor than to the ignorance and conservatism of those who ought to have cherished improvements. Chloroform was discovered in 1831; its use as an anaesthetic by Simpson in Edinburgh followed sixteen years later. Carbolic acid was discovered in 1834; its power to prevent putrefaction was vaguely known, but its systematic use as an antiseptic waited thirty years. Sodium salicylate was prepared in 1860; the useful medicament aspirin was marketed only in 1899. On the whole the most useful adaptations from science were those which gave scope to an inventor and a patent. Thus the peaceful uses of cellulose began with the mercerisation of cotton (1857) and the invention of celluloid (1869). Gun-cotton had already been discovered in 1846. Through industry, science offered to the lower middle-class, whose purchasing power was becoming enormous in the manufacturing state, substitutes for commodities like silk which nature could never provide in vast quantity: wood-pulp paper (c. 1860) instead of rag, which made the mass newspaper possible, margarine instead of butter (this last becoming a manufacture in the late 1870’s). These were new articles for which the market was open among the poor, and there were others whose sale justified the scientific treatment of manufacture, such as the brewing of beer. There were many more whose methods and products were capable of improvement, had taste or habit not kept demand at a low level. The soap industry, for example, only grew to the factory scale with domestic plumbing and a fresh attitude to hygiene. For the same reason, while Gregory’s powder and the black draught continued as household remedies, there was little change in the pharmaceutical branch of the chemical industry. Pharmacy was coming under the control of a few manufacturing drug-houses which naturally followed the leadership of the medical profession, but the great transformation of the pharmacopoeia, which owes much to the chemical research of this period, took place after it. Yet it was in a futile attempt to synthesise quinine that Perkin accidentally came across the first aniline dye, mauve (1856). In a short time the aniline-dye industry rose to a considerable magnitude, its activity thereafter stimulating renewed investigation. Given the clue, other synthetic dyestuffs were rapidly prepared; alizarin, the pigment of the madder plant, was synthesised in 1869, and indigo in 1870. Vegetable dyes were variable, expensive and restricted, and their cultivation was quickly ruined. The synthetic dyes, combining a wider range of unblended colours with more exact control, offered an opportunity to the textile industry which at first was used with more acumen than taste.

Towards the middle of the period it became possible to extend the empirical revolution in agricultural techniques which had begun in England a century before by applying chemical and physiological knowledge to the cultivation of plants. The nitrogen cycle and the photosynthetic formation of sugar were already partly understood. Pioneers like Wiegmann, Sprengel and Boussingault had already established the necessity for restoring to the soil mineral constituents taken up by the plant, the doctrine which the more popular writings of Liebig on agricultural chemistry disseminated. The first artificial fertilisers to be used were phosphates, manufactured from 1842, but later found in ‘basic slag’ from the phosphoric iron-ores used in the Bessemer and open-hearth steel processes. Ammoniacal liquors from gasworks were also taken to the fields before they were sold to the dye factories, but popular theory paid insufficient attention to the presence of nitrogen in the soil. Nitrates from the Chile beds were not used in quantity until after 1870. Fortunately the burden of supporting a larger population was not to descend wholly on agricultural science, since Europe had for many years consumed grain, and was now consuming other foodstuffs, from the American continent where farming methods were mechanically progressive and scientifically primitive.

Many problems of plant nourishment, especially that of nitrogen fixation from the atmosphere, could be understood only through the progress of microbiology, which began as a science in close association with organic chemistry and chemical industry. Pasteur, whose genius was responsible for nearly all the advance in this direction during the period, passed on from a study of the tartaric acids to the processes of fermentation in general, which could be regarded as a series of chemical reactions now that the composition of sugar, alcohol and acetic acid were known. Wine-makers and brewers were saved much loss by his investigation of ferments and his method of arresting degeneration by a gentle heat (pasteurisation). Pasteur was a strong vitalist in science, indeed his only difference with his friend Claude Bernard was on this point, and his philosophy determined the nature of his work, with its portentous influence. Fermentation occurs only in the presence of yeast, known since 1838 to consist of a mass of minute vegetable cells, and Pasteur vehemently opposed the mechanical or inorganic hypothesis of the ferment’s action put forward by Berzelius and Liebig (a crude version of the theory which has been adopted since the discovery of enzymes); for him the synthesis of alcohol was inseparable from the life-process of the yeast. From this he went on to make a far-reaching analogy between fermentation and putrefaction, which was universally believed to take place spontaneously in dead organic matter. Pasteur asserted that nothing could putrefy unless living agents were introduced into it, an assertion which provoked sharp controversy and was demonstrated (from 1859) by experiments in which putrefiable materials were kept wholesome in heat-sterilised vessels protected from contamination by air-borne dust.

Pasteur’s victory was hastened by his practical success in combating silk-worm disease and the phylloxera of the vineyards about 1865, but the great age of bacteriology in which the name of Koch is joined with that of Pasteur opened after 1870. The germ-theory of disease, justified by Pastern’s experiments on putrefaction, was a magnificent gift to humanity. Philosophically, however, vitalism had been a retarding influence in medical science since at the points where scientific inquiry was most necessary it interjected into orderly notions of cause and effect a mysterious and unanalysable life-force which was supposed to mark an absolute distinction in nature. In the mid-nineteenth century there was a reaction, and of the leaders of experimental physiology only Muller was a vitalist; in Germany Ludwig and Schwann, in France Magendie and Bernard, inclined to the opposite school. With the more forceful means of research offered by chemistry and powerful achromatic microscopes they applied themselves to the detailed examination of mechanisms: the tracing of a stimulus through the nervous system to the consequent muscular contraction or glandular secretion; the rendering available of food for the restoration of tissues and conversion into energy. Some problems demanded a finer technique for uncovering structures and testing their functions, such as Bell’s and Magendie’s work on sensory and motor nerves; empiricism was coming into its own. Others required a wider scientific perspective. Helmholtz’s excellent study of sense-perception, combining physics and anatomy, is an example of this, but more striking still were Bernard’s researches on metabolism which led him to one of the great early achievements of biochemistry. In 1846 he demonstrated the function of the pancreatic juice in splitting neutral fats into fatty acids and glycerine; in 1857 he isolated the carbohydrate glycogen, the form in which sugar is stored in the liver. He was also the first to recognise internal secretions and to examine their control through the nerves.

The discovery of glycogen broke down an old distinction between plant physiology, in which substances such as cellulose are built up from their inorganic constituents, and animal physiology, which was regarded as destructive, by showing that the animal body is also capable of synthesis. Apart from the theoretical and medical significance of these researches, they induced consideration of the body as an integrated organism whose parts are interrelated and their functions balanced. The nervous system could be seen not merely as the means of communication with the environment and of effecting volitions, but as the mechanism by which the temperature, secretions and general working of the body are regulated. The discovery and synthesis of the highly complex substances prepared by the body and on which its activities depend was begun. The old meta-physical problems of the nature of life were thrust farther back by science, as long chains of mechanism, each in itself subject to the normal laws of causality, were revealed.

At an even finer level of detail physiology faced the problems of the growth and viability of living tissue, which were brought within the general compass of cell theory, whose development sprang from the removal of technical limitations. About 1830 the achromatic microscope became a practicable instrument giving high magnification and good resolution; ten years later methods of staining sections, and towards 1870 microtomes for cutting them, were introduced. For centuries particular aspects of these problems had been discussed in embryology, and the egg as a special kind of cell retained its importance in cytology, though as yet the mechanism of inheritance (to which the theory of evolution gave fresh importance) was beyond investigation. Knowledge of cellular structure was more highly developed for plants than for animals when in 1831 the botanist Robert Brown discovered the nuclei of cells, and Schleiden in 1838 represented the plant as a community of cells. Schwann (1839) further generalised the theory and laid down the concept of the cell as the universal unit in the animal and vegetable kingdoms. The observation of cell-division followed soon after, and the distinction of the parts of the cell itself by von Mohl and Nageli. Histology had its own complexities; from work on unicellular organisms and the discovery of many different types of cell it gradually became apparent that no simple theory of these structural units was possible. Virchow, moreover, stressed (1858) the importance of pathological cells in disease, and like Pasteur and others who advocated the theory that micro-organisms were the cause of disease, argued strongly against spontaneous generation. When the classical definition of the cell, and the modem scope of cell theory in physiological thought were given by Schultze in 1861, the difficulties encountered in a biological doctrine of discontinuous structure seemed at least as great as those which faced atomic theory in physical science. And though the cruder notions of vitalism had disappeared by 1870, in cytology and microbiology the mysteries of the living state were still almost as obscure as they had been on the organic scale to the older physiologists.

The progress of experimental biology, standing apart from the main line of development of natural history, took place mainly in France and Germany. The English contribution was a formative concept growing directly out of the study of natural history which deflected and enriched every branch of biology. The memoirs by Darwin and Wallace, read to the Linnean Society in 1858, in which the theory of evolution by natural selection was first expounded, followed by the publication of the Origin of Species, appeared as a cataclysmic break with all sound thinking. It is now obvious that the scientific propositions which mid-Victorian Englishmen greeted with horror and alarm because they reflected upon the unique dignity of man and the literal truth of the Bible as a revelation of divine actions were the counterparts of the idea of progress which filled their thoughts with complacency. The study of history had endowed the concept of change, development, elaboration and specialisation with a central interest and adopted most naturally the metaphor of growth; the historical contrast between the contemporary state of civilisation and that of the past inspired a sense that the growth of arts, sciences and manufactures had been beneficent and would endure. This assumption was rejected only by a minority of romantics who, like Carlyle and Ruskin, distrusted the scientific movement and its fruits. The dynamic view of history impinged upon the cognate study of society, and upon science. It suggested that a static account of things as they are, incomplete because it ignores their coming into being and their passage into futurity, is even more vitally deficient because it ignores the very fact that what is observed is fluid and transitory. The introduction of time as a dimension in physics and astronomy has already been mentioned, and biology demanded a similar reform of its principles.

In one branch indeed, palaeontology, the obstinate retention of the static picture of the universe in deference to biological theory subjected the evidence to such violence of interpretation that geologists seem to have followed Darwin’s lead almost with relief. The hypothesis that fossils were relics of the flood or tests of man’s credulity was already threadbare in 1830, and geology was in any case assigning to the earth an age of the order of 100,000,000 years. The main techniques of the science had been worked out, the succession of strata and formations determined, and many parts of the world surveyed. Lyell, whose Principles of Geology (1830-3) was the authoritative treatise of the time, adopted the empirical principle that in renouncing early catastrophic theories of the formation of the earth’s crust its configuration should be attributed solely to the same slow processes of elevation and depression, deposition and erosion, that operate still. Yet, following Cuvier, the father of palaeontology, who had ascribed the disappearance of extinct species to successive catastrophes, he controverted all theories that living ones had originated from those found only in fossilised remains, directing his arguments particularly against Lamarck. The earth had a history of evolution, but each species was an immediate creation.

The doctrine of the orthodox naturalist was simple. At the creation there were an original pair of each distinct species, which by breeding in pure lines had populated the earth with its extant flora and fauna. The grounds for this belief were not solely theological, but rested upon the concept of species which it had been a main task of the previous century to define. The members of a species formed a homogeneous group, distinguished according to precisely selected characteristics which, in the perfected system of the Swedish naturalist Linnaeus, mainly referred to the reproductive mechanism; the species again were grouped in genera, orders and higher classes. Linnaeus had recognised the necessary artificiality of any taxonomy, and thought that possibly the orders represented only created pairs, the species having diverged within them. But these cautions were lost upon many of his successors who ignored the vagueness of specific distinctions and exaggerated the criterion of interfertility as the touchstone of common specific descent. As Wallace remarked, the concept of species had become circular when it was founded on principles which were themselves justified as corresponding to the natural idea of species. That the principles were convenient, but indefensible as determinants of the whole logic of botany was not widely appreciated in 1859, and the obvious scientific argument against any theory of evolution was that plants or animals having a common ancestor, though evolving along diverging paths, must be interfertile: since distinct species were not, by definition, interfertile they could not share a common descent.

The concept of biological evolution was older than Darwin. To Linnaeus varieties, and possibly species, which always breed true, had evolved from a common stock. Erasmus Darwin in 1794, the French zoologist Lamarck in 1802, had emphasised the dynamic aspect of nature but, in finding the cause of divergent change in a plastic power of the organism to pass on to its posterity its own adaptations—the inheritance of acquired characteristics—they overstrained credulity. Herbert Spencer, preferring Lamarck to Lyell, was already developing the philosophy of evolution before 1859. In the intervening half-century the accumulation of the geological evidence with its enormous extension of the period of time in which evolutionary processes could be supposed to have been effective and the ascendancy of the historical outlook helped to prepare the way for Darwin; even more influential, however, was the mechanism of evolution which he developed. This postulated that organisms do not inherit parental modifications acquired in life, but found that the individuals of each generation do differ slightly among themselves: minute and random variations occur (which Darwin assumed to be of a genetical, that is, inheritable character), assisting or impeding the individual in the normal activities and functions of its species. Darwin adopted Malthus’ law that populations increase faster than the means of their subsistence, inevitably causing a high mortality in each generation which only the fittest survive. The mid-nineteenth-century community well understood competition and the destruction of the feeble. Those individuals and their progeny that are best adapted to fill a given place in nature become specialised and diverge in type from their fellows, who either become extinct or are likewise adapted to some other manner of life. The operation of natural selection is frequently compared by Darwin to the artificial selection carried out by the breeder who allows only those individuals in each generation to reproduce which most nearly conform to the ideal type he has in mind, and who has by this means produced races of domestic animals of distinctive characteristics none of which closely resemble the wild species. Thus it was difficult for him to escape altogether the implications of teleology, though consciously he struggled against them, for it seems to be postulated that nature must purposefully adapt organisms to suit most efficiently each niche in the creation.

Darwin conceived his hypothesis of evolution early in his career as a naturalist, the long gestation of the Origin of Species being spent in the amassing of the detailed evidence upon which it could be represented as a plausible and consistent theory. He was well aware of the temerity of his thought and the strength of the opposition it would encounter. The marshalling of materials continued in successive volumes of which The Descent of Man (1871) was the most famous. The survey of the whole of natural history for this new purpose was a tremendous undertaking, and Darwin’s genius is most surely revealed in the skill with which he handled a subject in which almost every word had been written from a point of view diametrically opposed to his own. To an astonishing extent he was forced to rely upon his own observations and experiments to provide him with the answers to the novel questions he proposed. He had to re-create the method of biological inquiry before he could expect a reform to follow from his theory. The comparative development of single structures; the sexual physiology of plants; behaviour in animals; the geographical distribution of species; the selective mechanism of inheritance; ecology and palaeontology in many of their aspects—all these were branches of science which Darwin originated in their modem form almost de novo, and welded into a harmonious synthesis. In particular he paid great attention to artificial selection, a subject which science had neglected in spite of its considerable economic importance in agriculture, learning the secrets of London pigeon-fanciers and comparing these morphologically very distinct races with the almost indistinguishable separate species of the naturalist. The study of genetics, however, was in such a primitive state that no conclusive argument could be offered against the orthodox criticism, and Darwin’s somewhat loose reasoning on these problems has been unfavourably contrasted with Mendel’s precise experiments on inheritance ten years later. On the whole perhaps the state of ignorance was more propitious for the theory of evolution than otherwise. Darwin anticipated many other objections raised by his critics, such as the preservation of the purity of incipient species in the natural state, or the problematic usefulness of a rudimentary and imperfect organ. These were among the least compelling portions of the Origin of Species, whose strength lay rather in the broad generalising power of the theory, for a great deal of work remained to be done in comparative and developmental studies before the course of evolution of the higher animals and plants could be adequately traced. Evolutionary modification of the cells of which the organism is composed is, of course, the necessary foundation for any sound doctrine of evolution, but though this might have been realised in 1860, the progress of cytology is in fact scarcely reflected in the early literature of Darwinism.

The furious tide of criticism and the scornful ridicule which greeted the Origin of Species are well known. The conflict was bitter, yet short in relation to the momentous issues involved, penetrating as they did to the roots of Christian civilisation. Among naturalists Hooker and Huxley were immediately converted to Darwin’s view, and Lyell brought the geologists. Scientists generally had accepted Darwinism before the close of the period, but the initial criticism by such men as Agassiz, Owen and Sedgwick was by no means wholly occasioned by prejudice. There was enough weakness in parts of Darwin’s argument for scientific scepticism to be reasonable, some of the early rejoinders being based upon the same type of argument that in more recent times has given rise to the declaration that Darwinism is outmoded. If the older sceptics clung to the more romantic philosophy of nature of which vitalism was also a manifestation, others like Kolliker in Germany attacked Darwin’s theory not because it was evolutionary—various hypotheses of evolution, it was declared, were conceivable—but on account of its teleology, the lack of evidence of transitional forms, and the weak substantiation of its assumptions concerning inheritance. The palaeontological testimony for evolution had indeed hardly been declared in 1870, and the anthropological history of man was almost entirely unexplored. For the mass of Darwin’s opponents who followed the leadership of Bishop Wilberforce it was the light which was reflected by his ideas upon the literal interpretation of scripture and the intricate metaphysical problems of the human soul which was most obnoxious. The hostility to science aroused in the Papacy by discussion of the Copernican cosmology had long been dormant and among Protestant peoples faith in science and religion had framed a single philosophy in which the inspiration to a deeper veneration of the Creator was constantly urged as an incentive to the study of nature. This harmony was now disrupted. In 1864 Pius IX plainly announced in the Syllabus of modern errors the firm opposition of the Roman Catholic faith to the modern trend of civilisation, condemning liberalism, rationalism, and the influence of science (cf. ch. IV, pp. 90-3). From this position there was no retreat, but the Protestant Churches, having generally accepted and developed the scientific study of scriptural language and history that was already beginning in Germany before 1859, gradually came to terms with Darwinism. The shock of the conflict between science and religion was profound, and it was the authority of religion, rather than science, that emerged weakened from it. Darwin himself was an agnostic; the simple piety of Faraday was to become increasingly uncommon in men of science.

The medicine of the mid-nineteenth century was still far removed from experimental and theoretical biology, though towards the end of the period it was being suggested that it should rise from being an art to the status of a science. General practice altered little; the stethoscope and clinical the, rmometer were invented but the physician continued to prefer the old art of diagnosis to the use of instruments. Many of the most nauseous and useless concotions were banished from the pharmacopoeia, and some vegetable drugs of real effect, such as opium and digitalis, chemistry prepared in purer forms. As remedies from which a confident action against a specific disease could be expected were few (they included the administration of quinine against ague or malaria, and of mercury against syphilis), the patient had most to hope from a strong constitution aided by restoratives, with some attention to the relief of painful symptoms. Probably the training of medical men was more thorough in 1870 than in 1830, and they were certainly required to learn more general science. Hospitals were appalling places of death where the chances of the poor for surviving disease and childbirth were much less than those of richer people who could be treated at home. The rebuilding of these almost medieval institutions largely took place after this period. The care of the sick among Roman Catholic peoples remained, as always, in the hands of nursing orders. In Protestant states it had fallen to an abysmally low level. The first attempts to train respectable nurses were made in Germany and France; Florence Nightingale had studied the new methods before reorganising British military medicine during the Crimean War. What was needed here was not so much science as common sense and hygiene, but the administration of few hospitals had been reformed by 1870. The same statement is true of urban life, which at the best was unclean and at the worst was unimaginably squalid, though the state began to assume some responsibility after the first British Public Health Act of 1848. Very little science, in the intellectual sense, entered into the movement to provide towns with pure water, sewage disposal, public baths and decent workmen’s dwellings, which was inspired rather by the false theory that bad smells cause disease, charitable disgust at the animal lives of the lowest stratum, and experience that the better districts could not hope to escape the epidemics of the slums. Plague had gone with the black rat; in cleaner towns typhus and cholera accounted for fewer fives, though the origins and means of transmission of these diseases were unknown.

Operative surgery, on the other hand, benefited more directly by advances in organic chemistry. Its worst horrors were removed by the introduction of ether as an anaesthetic by Morton and Wells in the U.S.A. (1844), and of chloroform by Simpson in 1847. These pioneers had to withstand much professional and religious obscurantism and the early methods were very imperfect. The instruments and techniques employed in obstetrics and the small number of possible operations such as amputation and lithotomy were already highly developed, and the need for speed had made the best surgeons skilful. Little improvement was possible in this respect even with the aid of anaesthetics, for a limit to the surgeon’s action was still fixed by the very strong probability that the wound would become infected by gangrene or a septic condition. As mortality in surgical cases was normally of the order of 50 per cent, surgery was a last resort until Lister introduced his antiseptic system at Glasgow in 1865. Lister had been converted to the germ-theory of disease, and himself repeated a number of Pasteur’s experiments on putrefaction, devoting his leisure for the remainder of his life to the study of micro-organisms. His practice was designed to eliminate them from every possible source of infection by the use of carbolic acid on instruments, the patient, the operators’ hands, the dressings, and even the air itself, by means of a spray. Immediate success attended his experiments, gradually forcing his colleagues to follow the same procedures, and after 1870 giving surgery a scope and security hitherto inconceivable.

Lister’s discovery is a fine example of the process of scientific invention by one who was not himself a creative scientist. Disturbed in his early medical experience by the sepsis which was then the inescapable accompaniment of surgery, he made a comparison between suppuration of tissues and putrefaction of dead matter. In Pasteur’s researches he found a theory to account for the latter and in organic chemistry a powerful agent to hinder it. By experiment the details of his method were brought to perfection. The stages by which a reasoned application was effected in chemical industry or electrical engineering were not dissimilar, and whereas before 1830 technological and medical improvements were the result of accident or trial-and-error experimentation, since 1870 they have been largely the fruit of design. Perhaps the most decisive years of change in this respect were those between 1855 and 1865. Science, aware of its material as well as its philosophic purpose since the seventeenth century, only came within reach of making the former real in the mid-nineteenth. This did not involve any great modification in the nature of pure research because discovery and application were normally separated by a long interval, but it did mean that the function of the inventor was most important if material progress was to be advanced by science, and it was the lack of this scientifically experienced intermediary which had caused industrial progress to remain mainly in the hands of sheer empiricists up to about 1855. The early inventors, stealing a little primitive science (such as the principle of the steam-engine) and imitating in automatic machinery the actions of human weavers and spinners, had created the ugly society of the Industrial Revolution. Their clumsy genius was still strong—by 1851 they were using cast-iron for every suitable and unsuitable purpose—but as it had lost contact with science it was receiving no new inspiration. Its vision was limited to coal, iron and steam until the intervention of the scientific inventor between 1855 and 1870 brought in fresh materials and methods. The deflection at first was slight, and it cannot be supposed that conditions in, for example, an alkali works or a phosphorus-match shop were better than in a textile mill. The credit for alleviating the lot of labour must go to the humanitarian movement and the social legislation which it championed with increasing success from 1833 onwards. Moreover, improvements in the standard of living of the peoples owed less to science than to cheap bread and tariff reform. In England, for example, between 1830 and 1850 wages remained fairly stationary, while the cost of living showed a general tendency to fall. From 1850 to 1870 real wages were rising in trend, once prices ceased to mount steeply following the collapse of the 1857 boom (ch. n, pp. 47-8). The worst tenements, the longest hours, the sharpest starvation were gone or going. The crude death-rate did not show much sign of decreasing, however, being stable at slightly over 22 per thousand, though this was always less than the mortality in France or Belgium in spite of the large French peasant population. The colder and less densely peopled Scandinavian countries were far healthier, the death-rate in Denmark falling from 20-3 in 1840 to 19 in 1870—a little less, perhaps, than the level in the English countryside at the same date. Significant improvements in health as in manufacturing techniques were achieved by science only after 1870.

The part of the inventor in techniques was played in the history of thought by such men as Comte and Spencer; and their function was not merely to elucidate the intellectual and philosophical implications of scientific knowledge, for just as an invention may provoke a fundamental investigation in science, so Spencer (for instance) stimulated biologists to examine the principles of their studies more carefully. Such men have not been highly esteemed by historians of either science or philosophy, but their ideas, in spite of some deficiency of fact and logic, have passed into the general consciousness. The Positivist school was never dominant; nevertheless, the acceptance of science as embracing a type of knowledge peculiarly exact, rigorous and practical has passed into language. As men adopted the idea of progress, as at last they began to see their own world as richer and more learned than that of Rome, they also became convinced that it was the scientific mind especially which had brought this happy state to be, and trusted increasingly to its benevolent powers for the future. Popular interest in science turned from descriptive natural history, astronomy and drawing-room marvels to the constructive sciences of electricity and chemistry. Positively, science meant knowledge and power. Nothing is more formidable than the doctrine which was already being taught that life is plastic and that science does not submit to disease, labour and humility as pillars of creation. Negatively, that which did not fall within the province of science was not knowledge and was therefore arbitrary or conventional. Against this thesis the Roman Catholic Church had set itself firmly by 1870, defining the limits which scientific pronouncements might not transgress; the Protestant Churches, though not yet routed by Darwinism, were less successful in maintaining that moral laws are as certain and clear as those of science. It is often supposed by those who overlook the import of the development of toleration, rationalism and free-thinking, that the theory of evolution came as an abrupt and single shock to traditional religion, whereas in fact the denial of other authority, though a deduction which many early scientists personally refused to draw, is intrinsic in the scientific method. Darwin did not invent the doctrine that science follows the simplest hypothesis, and the crude argument from Providence which he expelled from natural history had long been rejected in physical science and serious philosophy. Materialism, in the strictest sense the belief that all the phenomena of the universe, including man, are reducible to the physicist’s reality of matter and energy; perception of the inconsistency between a literal reading of Old Testament chronology and the considered verdicts of science; critical examination, in the Leben Jesu of D. F. Strauss (1836) and the works of the Tubingen school, of the historical authenticity of the Gospels; all this was building the mid-nineteenth-century crisis of religion long before 1859 (cf. ch. IV, pp. 101-2). If in England and America free speculation, which had formerly been cautious, broke forth suddenly in the reviews during the ’sixties and ’seventies, anti-clerical scepticism had been a touchstone of liberalism in Catholic Europe since the time of Voltaire. Yet Darwinism acted as a catalytic concept in the conflict of loyalties which it aroused, and which was all the greater because Protestant theology had tended to assert that its dogmas were defensible by reason alone and did not rest upon blind faith. It was the last blow to the final authority of Scripture, but it by no means filled the last loop-hole in the scientific claim to omniscience, for there were many more subtle refuges to which the plea for the necessity of Design might retire. Science was increasingly demonstrating that the operation of chance, as conceived by a statistician, does not produce sheer confusion, and that at least the existing universe with its existing species was not the immediate, immutable product of creation. Similarly, in formal philosophy the influence of Darwin extended far beyond that of Herbert Spencer in making biology stand in relation to nineteenth-century thought as mechanics had to that of the late seventeenth. But the adjustment of the moral and ethical image of man as a being not degenerate, but progressively evolving from Pithecanthropus erectus through primitive society to civilisation, had scarcely begun in 1870. In this the new sciences of psychology and anthropology have played a vital part.

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