The knowledge of the Natural Sciences among the Greeks and Romans was derived principally from the Egyptians and Babylonians. The Phœnicians in their voyages, also, necessarily paid considerable attention to Astronomy. Their Cynosura consisted of the tail of the Little Bear, by which they steered. The great names in Greek Astronomy are Aratus, Hipparchus, and Ptolemy.
From the fancies of Astrology, in which the early Arabs largely indulged, and which, though discountenanced by Mahomet himself, have never been wholly abandoned by their descendants, a not unnatural transition, led to the study of Astronomy. Under the patronage of the AbbasideCaliph Al-Mamun(813-833A. D.) this science made rapid progress.
Astronomy was zealously studied in the famous schools of Bagdad and Cordova.
TheAlmagest, or System of Astronomy, by Ptolemy, was translated into Arabic by Alhazi and Sergius as early as 812. In the Tenth Century, Albaten observed the advance of the line of the apsides in the earth’s orbit; Mohammed-ben-Jeber-al-Batani, the obliquity of the ecliptic; Alpetragius wrote a theory of the planets; and Abul-Hassan-Ali, on astronomical instruments. The obliquity of the ecliptic, the diameter of the earth, and even the precession of the equinoxes, were then calculated with commendable accuracy; and shortly after, Abul-Mezar’sIntroduction to Astronomyand hisTreatise on the Conjunction of the Planets, with theElementsof Al-Furjanee (though this last author was largely indebted to the Egyptian labors of Ptolemy), proved that the caliph’s liberality had been well bestowed.But Al-Batinee, a native of Syria (879-920A. D.), surpassed all his predecessors in the nicety alike of his observations and computations. Geber, at Seville, constructed (1196A. D.) the first astronomical observatory on record; and Ebn-Korrah in Egypt proved by his example that the Arabs could be even better astronomers than the Greeks.
Ulug Bekh, grandson of the great Tamerlane, was a diligent observer. He established an academy of astronomers at Samarcand, the capital of his dominions, and constructed magnificent instruments. Ulug Bekh, too, made a catalogue of the fixed stars—the only one that had been compiled since that of Hipparchus, sixteen centuries previously.
Gradually, by their intercourse with civilized nations, the Arabian conquerors were themselves subjected to the humanizing influence of letters, and, after 749A. D., or during the reign of the Abassides, literature, arts, and sciences appeared, and were generously fostered under the splendid sway, first of Almansor (754-775), and afterward of the celebrated Harun-al-Raschid (786-808). Learned men were now invited from many countries and remunerated for their labors with princely munificence; the works of the best Greek, Syriac, and old Persian writers were translated into Arabic, and spread abroad in numerous copies. The Caliph Al-Mamun, who reigned from 813 to 833, offered to the Greek emperor five tons of gold and a perpetual treaty of peace on condition that the philosopher Leo should be allowed to give instruction to the former. Under the same Caliph the famous schools of Bagdad, Basra, Bokhara, and Kufa were founded, and large libraries were collected in Alexandria, Cairo, and Bagdad. The school of Cordova in Spain soon rivaled that of Bagdad, and in the Tenth Century the Arabs were everywhere the preservers and distributers of knowledge.
Pupils from France and other European countries repaired to Spain in great numbers, to study mathematics and medicine under the Arabs. There were fourteen academies,with many preparatory and upper schools, in Spain, and five very considerable public libraries; that of the Caliph Hakem containing, as is said, more than 600,000 volumes.
In Geography, History, Philosophy, Medicine, Physics, and Mathematics the Arabians rendered important services to science; and the Arabic words still employed in science—such as algebra, alcohol, azimuth, zenith, nadir, with many names of stars, etc. (seeThe Arabian Heavens, pages 106-120 of Vol. I)—remain as indications of their influence on the early intellectual culture of Europe. But Geography owes most to them during the Middle Ages. In Africa and Asia, the boundaries of geographical science were extended, and the old Arab treatises on geography and works of travels in several countries by Abulfeda, Edrisi, Leo Africanus, Ibn Batuta, Ibn Foslan, Ibn Jobair, Albiruni the astronomer, and others, are still interesting.
The structure of the earth received little attention from the ancients; the extent of its surface known was limited, and the changes upon it were neither so speedy nor violent as to excite special attention. The only opinions deserving to be noticed are those of Pythagoras and Strabo, both of whom observed the phenomena which were then altering the surface of the earth, and proposed theories for explaining the changes that had taken place in geological time. The first held that, in addition to volcanic action, the change in the level of sea and land was owing to the retiring of the sea; while the other maintained that the land changed its level, and not the sea, and that such changes happened more easily to the land below the sea because of its humidity.
From the fall of the Roman empire, during the Dark Ages, the physical sciences were neglected. In the Tenth Century, Avicenna, Omar, and other Arabian writers commented on the works of the Romans, but added little of their own.
Geological phenomena attracted attention in Italy in the Sixteenth Century, the absorbing question then beingas to the nature of fossils; only a few maintained that they were the remains of animals. Two centuries elapsed before the opinion was generally adopted.
Aristotle was the first who collected, in his workOn Meteors, the current prognostics of the weather. Some of these were derived from the Egyptians, who had studied the science as a branch of Astronomy, while a considerable number were the result of his own observation. The next writer upon this subject was Theophrastus, one of Aristotle’s pupils, who classified the opinions commonly received regarding the weather under four heads, viz., the prognostics of rain, of wind, of storm, and of fine weather. The subject was discussed purely in its popular and practical bearings, and no attempt was made to explain phenomena whose occurrence appeared so irregular and capricious. Cicero, Virgil, and a few other writers also wrote on the subject; but the treatise of Theophrastus contains nearly all that was known down to comparatively recent times. Partial explanations were attempted by Aristotle and Lucretius, but their explanations were vague, and often absurd.
In this dormant condition meteorology remained for ages, and no progress was made till proper instruments were invented for making real observations with regard to the temperature, the pressure, the humidity, and the electricity of the air.
Solomon spoke of “trees, from the cedar in Lebanon even to the hyssop that springeth out of the wall.” There is reason also to believe that Zoroaster devoted some attention to plants, and that this study early engaged some of the philosophers of Greece. The oldest botanical work which has come down to us is that of Theophrastus, the pupil of Aristotle, who flourished in the fourth centuryB. C.His descriptions of plants are very unsatisfactory, but his knowledge of their organs and of vegetable physiology may well be deemed wonderful. It was not, indeed, till after the revival of letters in Western Europe, that it was ever again studied as it had been by him. About four hundredyears after Theophrastus, in the First Century of the Christian era, Dioscorides of Anazarbus, in Asia Minor—a herbalist, however, rather than a botanist—described more than 600 plants in a work which continued in great repute throughout the Middle Ages.
About the same time, the elder Pliny devoted a share of his attention to Botany, and his writings contain some account of more than 1,000 species, compiled from various sources and mingled with many errors. Centuries elapsed without producing another name worthy to be mentioned. It was among the Arabians that the science next began to be cultivated, about the close of the Eighth Century. The greatest name of this period is Avicenna. Among the Arabs, Botany, like Chemistry, was chiefly studied as subsidiary to medicine; but as an adjunct to the old herbal pharmacopœia, it received close attention. The principal mercurial and arsenical preparations of themateria medica, the sulphates of several metals, the properties of acids and alkalies, the distillation of alcohol—in fine, whatever resources chemistry availed itself of up to a very recent date—were, with their practical application, known to Er-Razi and Geber. In fact, the numerous terms borrowed from the Arabic language—for instance, alcohol, alkali, alembic, and others—with the signs of drugs and the like, still in use among modern apothecaries, remain to show how deeply this science is indebted to Arab research.
Aristotle seems to have been the first to study Zoology. Some of the groups he established still retain their place in the most modern classifications. His two great sections of the Animal Kingdom consisted of Enanima (red blood) and Anima (having a circulation of colorless fluid). Ælian and Pliny wrote on the subject, but they indulged largely in fables. There was little advance in the science during the Dark and Middle Ages. TheBestiarieswere written for the sake of moral teaching, and the animals had to behave with that end in view. Albertus Magnus is the only famous name in this department before the revival of learning.
The shining light of the Thirteenth Century was Roger Bacon. HisOpus Majusis “at once the Encyclopædia and the Novum Organum of the Thirteenth Century.” In this, besides other branches of scientific research, he devotes a rapid examination to questions of Climate, Hydrography, Geography, and Astrology. Scientific research, however, was out of date, and from the educated world Roger Bacon received small recognition. His writings earned only a prison from his own Order, and he died, in his own words, “unheard, forgotten, buried.”
The Revival of Learning, commonly known as the Period of the Renaissance, naturally entailed renewed interest in the sciences as well as the arts. Green gives a comprehensive view of it:
“The last royalist had only just laid down his arms when the little company who were at a later time to be known as the Royal Society gathered round Wilkins at Oxford. It is in this group of scientific observers that we catch the secret of the coming generation. From the vexed problems, political and religious, with which it had so long wrestled in vain, England turned at last to the physical world around it, to the observation of its phenomena, to the discovery of the laws which govern them. The pursuit of physical science became a passion; and its method of research, by observation, comparison, and experiment, transformed the older methods of inquiry in matters without its pale. In religion, in politics, in the study of man and of nature, not faith but reason, not tradition but inquiry, were to be the watchwords of the coming time. The dead-weight of the past was suddenly rolled away, and the new England heard at last and understood the call of Francis Bacon.“Bacon had already called men with a trumpet-voice to such studies; but in England at least Bacon stood before his age. The beginnings of physical science were more slow and timid there than in any country of Europe. Only two discoveries of any real value came from English research before the Restoration; the first, Gilbert’s discovery of terrestrial magnetism in the close of Elizabeth’s reign; the next, the great discovery of the circulation of the blood, which was taught by Harvey in the reign of James. Apart from these illustrious names England took little share in the scientific movement of the continent; and her whole energies seemed to be whirled into the vortex of theology and politics by the Civil War. But the war had not reached its end when a little group of studentswere to be seen in London, men ‘inquisitive,’ says one of them, ‘into natural philosophy and other parts of human learning, and particularly of what hath been called the New Philosophy,... which from the times of Galileo at Florence, and Sir Francis Bacon (Lord Verulam) in England, hath been much cultivated in Italy, France, Germany, and other parts abroad, as well as with us in England.’ The strife of the time indeed aided in directing the minds of men to natural inquiries. ‘To have been always tossing about some theological question,’ says the first historian of the Royal Society, Bishop Sprat, ‘would have been to have made that their private diversion, the excess of which they disliked in the public. To have been eternally musing on civil business and the distresses of the country was too melancholy a reflection. It was nature alone which could pleasantly entertain them in that estate.’ Foremost in the group stood Doctors Wallis and Wilkins, whose removal to Oxford, which had just been reorganized by the Puritan Visitors, divided the little company into two societies. The Oxford society, which was the more important of the two, held its meetings at the lodgings of Dr. Wilkins, who had become Warden of Wadham College, and added to the names of its members that of the eminent mathematician Dr. Ward, and that of the first of English economists, Sir William Petty. ‘Our business,’ Wallis tells us, ‘was (precluding matters of theology and state affairs) to discourse and consider of philosophical inquiries and such as related thereunto, as Physick, Anatomy, Geometry, Astronomy, Navigation, Statics, Magnetics, Chymicks, Mechanicks, and Natural Experiments: with the state of these studies, as then cultivated at home and abroad. We then discoursed of the circulation of the blood, the valves in thevenæ lacteæ, the lymphatic vessels, the Copernican hypothesis, the nature of comets and new stars, the satellites of Jupiter, the oval shape of Saturn, the spots in the sun and its turning on its own axis, the inequalities and selenography of the moon, the several phases of Venus and Mercury, the improvement of telescopes, the grinding of glasses for that purpose, the weight of air, the possibility or impossibility of vacuities, and Nature’s abhorrence thereof, the Torricellian experiment in quicksilver, the descent of heavy bodies and the degree of acceleration therein, and divers other things of like nature.’“The other little company of inquirers, who remained in London, was at last broken up by the troubles of the Second Protectorate; but it was revived at the Restoration by the return to London of the more eminent members of the Oxford group. Science suddenly became the fashion of the day. Charles was himself a fair chymist, and took a keen interest in the problems of navigation. The Duke of Buckingham varied his freaks of riming, drinking,and fiddling by fits of devotion to his laboratory. Poets like Dryden and Cowley, courtiers like Sir Robert Murray and Sir Kenelm Digby joined the scientific company to which in token of his sympathy with it the King gave the title of ‘The Royal Society.’ The curious glass toys called Prince Rupert’s drops recall the scientific inquiries which, with the study of etching, amused the old age of the great cavalry leader of the Civil War. Wits and fops crowded to the meetings of the new society. Statesmen like Lord Somers felt honored at being chosen its presidents. Its definite establishment marks the opening of a great age of scientific discovery in England. Almost every year of the half century which followed saw some step made to a wider and truer knowledge. Our first national observatory rose at Greenwich, and modern astronomy began with the long series of astronomical observations which immortalized the name of Flamsteed. His successor, Halley, undertook the investigation of the tides, of comets, and of terrestrial magnetism. Hooke improved the microscope, and gave a fresh impulse to microscopical research. Boyle made the air-pump a means of advancing the science of pneumatics, and became the founder of experimental chymistry. Wilkins pointed forward to the science of philology in his scheme of a universal language. Sydenham introduced a careful observation of nature and facts which changed the whole face of medicine. The physiological researches of Willis first threw light upon the structure of the brain. Woodward was the founder of mineralogy. In his edition of Willoughby’sOrnithology, and in his ownHistory of Fishes, John Ray was the first to raise zoology to the rank of a science; and the first scientific classification of animals was attempted in hisSynopsis of Quadrupeds. Modern botany began with hisHistory of Plants, and the researches of an Oxford professor, Robert Morison; while Grew divided with Malpighi the credit of founding the study of vegetable physiology. But great as some of these names undoubtedly are, they are lost in the lustre of Isaac Newton. Newton was born at Woolsthorpe in Lincolnshire, on Christmas Day, in the memorable year which saw the outbreak of the Civil War. In the year of the Restoration he entered Cambridge, where the teaching of Isaac Barrow quickened his genius for mathematics, and where the method of Descartes had superseded the older modes of study. From the close of his Cambridge career his life became a series of great physical discoveries. At twenty-three he facilitated the calculation of planetary movements by his theory of Fluxions. The optical discoveries to which he was led by his experiments with the prism, and which he partly disclosed in the lectures which he delivered as mathematical professor at Cambridge, were embodied in the theory of light which he laid before the Royal Society onbecoming a Fellow of it. His discovery of the law of gravitation had been made as early as 1666; but the erroneous estimate which was then generally received of the earth’s diameter prevented him from disclosing it for sixteen years; and it was not till the eve of the Revolution that thePrincipiarevealed to the world his new theory of the Universe.”
“The last royalist had only just laid down his arms when the little company who were at a later time to be known as the Royal Society gathered round Wilkins at Oxford. It is in this group of scientific observers that we catch the secret of the coming generation. From the vexed problems, political and religious, with which it had so long wrestled in vain, England turned at last to the physical world around it, to the observation of its phenomena, to the discovery of the laws which govern them. The pursuit of physical science became a passion; and its method of research, by observation, comparison, and experiment, transformed the older methods of inquiry in matters without its pale. In religion, in politics, in the study of man and of nature, not faith but reason, not tradition but inquiry, were to be the watchwords of the coming time. The dead-weight of the past was suddenly rolled away, and the new England heard at last and understood the call of Francis Bacon.
“Bacon had already called men with a trumpet-voice to such studies; but in England at least Bacon stood before his age. The beginnings of physical science were more slow and timid there than in any country of Europe. Only two discoveries of any real value came from English research before the Restoration; the first, Gilbert’s discovery of terrestrial magnetism in the close of Elizabeth’s reign; the next, the great discovery of the circulation of the blood, which was taught by Harvey in the reign of James. Apart from these illustrious names England took little share in the scientific movement of the continent; and her whole energies seemed to be whirled into the vortex of theology and politics by the Civil War. But the war had not reached its end when a little group of studentswere to be seen in London, men ‘inquisitive,’ says one of them, ‘into natural philosophy and other parts of human learning, and particularly of what hath been called the New Philosophy,... which from the times of Galileo at Florence, and Sir Francis Bacon (Lord Verulam) in England, hath been much cultivated in Italy, France, Germany, and other parts abroad, as well as with us in England.’ The strife of the time indeed aided in directing the minds of men to natural inquiries. ‘To have been always tossing about some theological question,’ says the first historian of the Royal Society, Bishop Sprat, ‘would have been to have made that their private diversion, the excess of which they disliked in the public. To have been eternally musing on civil business and the distresses of the country was too melancholy a reflection. It was nature alone which could pleasantly entertain them in that estate.’ Foremost in the group stood Doctors Wallis and Wilkins, whose removal to Oxford, which had just been reorganized by the Puritan Visitors, divided the little company into two societies. The Oxford society, which was the more important of the two, held its meetings at the lodgings of Dr. Wilkins, who had become Warden of Wadham College, and added to the names of its members that of the eminent mathematician Dr. Ward, and that of the first of English economists, Sir William Petty. ‘Our business,’ Wallis tells us, ‘was (precluding matters of theology and state affairs) to discourse and consider of philosophical inquiries and such as related thereunto, as Physick, Anatomy, Geometry, Astronomy, Navigation, Statics, Magnetics, Chymicks, Mechanicks, and Natural Experiments: with the state of these studies, as then cultivated at home and abroad. We then discoursed of the circulation of the blood, the valves in thevenæ lacteæ, the lymphatic vessels, the Copernican hypothesis, the nature of comets and new stars, the satellites of Jupiter, the oval shape of Saturn, the spots in the sun and its turning on its own axis, the inequalities and selenography of the moon, the several phases of Venus and Mercury, the improvement of telescopes, the grinding of glasses for that purpose, the weight of air, the possibility or impossibility of vacuities, and Nature’s abhorrence thereof, the Torricellian experiment in quicksilver, the descent of heavy bodies and the degree of acceleration therein, and divers other things of like nature.’
“The other little company of inquirers, who remained in London, was at last broken up by the troubles of the Second Protectorate; but it was revived at the Restoration by the return to London of the more eminent members of the Oxford group. Science suddenly became the fashion of the day. Charles was himself a fair chymist, and took a keen interest in the problems of navigation. The Duke of Buckingham varied his freaks of riming, drinking,and fiddling by fits of devotion to his laboratory. Poets like Dryden and Cowley, courtiers like Sir Robert Murray and Sir Kenelm Digby joined the scientific company to which in token of his sympathy with it the King gave the title of ‘The Royal Society.’ The curious glass toys called Prince Rupert’s drops recall the scientific inquiries which, with the study of etching, amused the old age of the great cavalry leader of the Civil War. Wits and fops crowded to the meetings of the new society. Statesmen like Lord Somers felt honored at being chosen its presidents. Its definite establishment marks the opening of a great age of scientific discovery in England. Almost every year of the half century which followed saw some step made to a wider and truer knowledge. Our first national observatory rose at Greenwich, and modern astronomy began with the long series of astronomical observations which immortalized the name of Flamsteed. His successor, Halley, undertook the investigation of the tides, of comets, and of terrestrial magnetism. Hooke improved the microscope, and gave a fresh impulse to microscopical research. Boyle made the air-pump a means of advancing the science of pneumatics, and became the founder of experimental chymistry. Wilkins pointed forward to the science of philology in his scheme of a universal language. Sydenham introduced a careful observation of nature and facts which changed the whole face of medicine. The physiological researches of Willis first threw light upon the structure of the brain. Woodward was the founder of mineralogy. In his edition of Willoughby’sOrnithology, and in his ownHistory of Fishes, John Ray was the first to raise zoology to the rank of a science; and the first scientific classification of animals was attempted in hisSynopsis of Quadrupeds. Modern botany began with hisHistory of Plants, and the researches of an Oxford professor, Robert Morison; while Grew divided with Malpighi the credit of founding the study of vegetable physiology. But great as some of these names undoubtedly are, they are lost in the lustre of Isaac Newton. Newton was born at Woolsthorpe in Lincolnshire, on Christmas Day, in the memorable year which saw the outbreak of the Civil War. In the year of the Restoration he entered Cambridge, where the teaching of Isaac Barrow quickened his genius for mathematics, and where the method of Descartes had superseded the older modes of study. From the close of his Cambridge career his life became a series of great physical discoveries. At twenty-three he facilitated the calculation of planetary movements by his theory of Fluxions. The optical discoveries to which he was led by his experiments with the prism, and which he partly disclosed in the lectures which he delivered as mathematical professor at Cambridge, were embodied in the theory of light which he laid before the Royal Society onbecoming a Fellow of it. His discovery of the law of gravitation had been made as early as 1666; but the erroneous estimate which was then generally received of the earth’s diameter prevented him from disclosing it for sixteen years; and it was not till the eve of the Revolution that thePrincipiarevealed to the world his new theory of the Universe.”
Ever since the Fifteenth Century, when Copernicus revived the ancient theory of Pythagoras that the planets revolved around the sun (a theory left in an imperfect state and demonstrated later by Kepler, Galileo, Newton, and others) astronomical research has progressed steadily. It must be remembered, however, thatDe Revolutionibus Orbium, which met with great opposition, contained nothing regarding the laws of motion, for these had not been as yet discovered, and Saturn marked the boundaries of the Solar System. Copernicus assigned the “fixed stars” to a sphere, as in Ptolemy’s heavens (seepage 331).
The great Danish astronomer, Tycho Brahe, whose idea of the Solar System is represented onpage 343, was his opponent. Brahe, however, a devoted student, a man of wealth, the favorite of kings and princes, and the proud possessor of the Castle of Uraniberg (City of the Heavens), an observatory equipped with fine instruments and built for him by Frederick II, King of Denmark, on the island of Hueen, and after his death the protégé of Rudolph II at Benatek, near Prague, contributed greatly to the advancement of the science by means of his discoveries, computations, solar and lunar tables, and catalogue of stars. He, like Copernicus, placed the “fixed stars” in an outer sphere. His observations on the planets were made to prove the truth of his system. This mass of observations was used instead by Johann Kepler, who had been his assistant at the Benatek Observatory, to prove Copernicus’s theory. Of Kepler, the discoverer of the three famous laws, who gave a complete theory of solar eclipses, calculated the transits of Mercury and Venus, and made numerous discoveries in optics and general physics, Proctor says:
“Kepler was not merely an observer and calculator; he inquired with great diligence into the physical causes of every phenomenon, and made a near approach to the discovery of that great principle which maintains and regulates the planetary motions. He possessed some very sound and accurate notions of the nature of gravity, but unfortunately conceived it to diminish simply in proportion to the distance, although he had demonstrated that the intensity of light is reciprocally proportional to the surface over which it is spread, or inversely as the square of the distance from the luminous body.”
“Kepler was not merely an observer and calculator; he inquired with great diligence into the physical causes of every phenomenon, and made a near approach to the discovery of that great principle which maintains and regulates the planetary motions. He possessed some very sound and accurate notions of the nature of gravity, but unfortunately conceived it to diminish simply in proportion to the distance, although he had demonstrated that the intensity of light is reciprocally proportional to the surface over which it is spread, or inversely as the square of the distance from the luminous body.”
Great names follow in rapid succession. One of Kepler’s contemporaries was Galileo Galilei, the discoverer of the “three laws of motion” and the relation of time and space in falling bodies, the first to apply the newly invented telescope to the observation of the heavens and the discoverer of four satellites of Jupiter (named by him the “Medeiran Stars” in honor of his patron). He also detected spots on the sun’s disk, the phases of Venus, and irregularities on the moon’s surface, and declared the Milky Way to be composed of a countless tract of separate stars.
When we remember the limited power of the telescope of the age, we can but marvel, not at how little, but how much was known regarding the starry skies.
During this period, numerous observers rendered great service to Astronomy, and other scientists were engaged in making useful drawings, charts, maps, tables, and catalogues of stars.
To this period also belongs John Bayer of Augsburg, who published a description of the constellations with maps upon which the stars were marked with the letters of the Greek Alphabet—a convenient method that was universally adopted and is still in use. Other names include Gassendi, Riccioli, Grimaldi, and Hevelius—the latter a rich citizen of Dantzig, who had a fine observatory of his own, where he worked for forty years. His drawings and descriptions of the moon, his researches on comets, which he still believed moved in parabolas, and his celestial charts engaged most of his attention.
The Dutch astronomer Huygens (born in 1629) is famous for his improvements in the telescope use of the pendulum clock and developments in the machinery of astronomical instruments. He discovered the ring of Saturn and four of his satellites. Edmund Halley, an English astronomer (born in 1656), also took a great interest in the telescope, and went to Dantzig to settle a controversy between Robert Hooke and Hevelius regarding the best glasses for use in astronomical observations; for Hevelius still worked with the ancient instruments, while Hooke believed in the lens.
Halley revived the ancient idea that comets belonged to the Solar System, and predicted that the comet of 1681 would return to its perihelion in 1759. This was the first prediction of its kind verified.
During the last quarter of the Seventeenth Century, the telescope assumes importance and two great observatories begin their work. In 1670 the Paris Observatory, of which Cassini was made director, was finished, and five years later the Greenwich Observatory, where Flamsteed was installed as royal astronomer.
Of Cassini, Lalande remarks that under him Astronomy underwent revolutions, and in France he was regarded as the “creator of the science.” Cassini discovered that Saturn’s ring was double and found four satellites of Jupiter.
Flamsteed’s observations on planets, satellites, comets, “fixed stars,” and his catalogue of 2,884 stars were valuable contributions to science; and hisHistoria Cœlestisis said to have “formed a new era in sidereal astronomy.”
Flamsteed was succeeded by Halley, particularly famed for his investigations of comets. The next great astronomical event was the discovery of Uranus by Sir William Herschel in 1781. Sir William Herschel also discovered two more of Saturn’s satellites, and began the great work of resolving the Milky Way and other clusters into swarms of suns, single stars into double and triple stars, inquiriesinto the mysteries of the nebulæ, and in every way enlarging the general conception of the sidereal universe.
To the end of the Eighteenth and beginning of the Nineteenth Centuries belongs the brilliant French astronomer and mathematician Laplace, who published in 1799-1808 hisMécanique Céleste, in which he announced his Nebular Hypothesis (described on page 433 of Vol. II. The discoveries of the Planetoids are described onpages 396-403, and that of Neptune in 1846 onpages 430-432). The latest important additions to the Solar System are the discovery by Prof. Barnard of Jupiter’s Fifth Satellite in 1892 and Saturn’s Ninth by Prof. W. H. Pickering in 1904. The discovery even of a Seventh Satellite of Jupiter has just been announced from the Lick Observatory.
It would be impossible to mention the names of the astronomers whose work from the middle of the last century to its closing years has been distinguished in various fields. Space only permits brief mention of the new methods of research by means of the spectroscope and celestial photography. With the first the name of the English astronomer, William Huggins, is identified and has yielded most important and startling information regarding the composition of heavenly bodies, and with the application of the photographic telescope these new methods have created a revolution in astronomical observation.
It may be interesting to gain a slight idea of the numbers of stars revealed by the camera by referring to Sir Robert Ball:
“If we take a position on the equator, from whence, of course, all the heavens can be completely seen in the lapse of six months, the number of stars that can be reckoned with the unaided eye will, according to Houzeau, amount to about six thousand. If we augment our unaided vision by a telescope of even small dimensions, such as three inches in diameter, the number of stars in the Northern Hemisphere alone is upward of three hundred thousand. We may assume that the Southern Hemisphere has an equally numerous star-population, so that the entire multitude visible with this optical aid is about six hundred thousand. Thus we see thatthe use of a telescope small enough to be carried in the hands suffices to multiply the lucid stars one-hundredfold. Great telescopes no doubt soon show us that the hundreds of thousands are only the brighter members of a host of millions, and now we receive the assurance of photography that the telescopic stars are only the more conspicuous members of that vast universe. Mr. Roberts indeed declares that the multitudes of stars on the photographic plate grow with each increase of exposure to such a degree that it would almost seem as if the plate would be a wellnigh continuous mass of stars if the operations could be sufficiently protracted.”
“If we take a position on the equator, from whence, of course, all the heavens can be completely seen in the lapse of six months, the number of stars that can be reckoned with the unaided eye will, according to Houzeau, amount to about six thousand. If we augment our unaided vision by a telescope of even small dimensions, such as three inches in diameter, the number of stars in the Northern Hemisphere alone is upward of three hundred thousand. We may assume that the Southern Hemisphere has an equally numerous star-population, so that the entire multitude visible with this optical aid is about six hundred thousand. Thus we see thatthe use of a telescope small enough to be carried in the hands suffices to multiply the lucid stars one-hundredfold. Great telescopes no doubt soon show us that the hundreds of thousands are only the brighter members of a host of millions, and now we receive the assurance of photography that the telescopic stars are only the more conspicuous members of that vast universe. Mr. Roberts indeed declares that the multitudes of stars on the photographic plate grow with each increase of exposure to such a degree that it would almost seem as if the plate would be a wellnigh continuous mass of stars if the operations could be sufficiently protracted.”
Naturally the past years have witnessed the making of new catalogues and maps of stars, and many valuable computations of parallaxes, etc. Some of the results obtained by these new methods are described in the chapters on the Nebulæ and Swarms of Suns, The Great Nebula of Orion, and The Colored, Double, Multiple, Binary, Variable, and Temporary Stars in Vol. I. From this brief survey of the progress of Astronomy the fact will be appreciated, therefore, that all the discoveries and researches have resulted in a larger conception of the universe, and the Solar System sinks into insignificance in the vast ocean of stars and suns.
The study of the Earth’s crust and its contents divested of superstition dates from the end of the Seventeenth Century. Nicolaus Steno (1638-1687), a Dane, devoted himself to geology, and in 1669 observed successive layers of strata. He is called “the father of Palæontology.” In 1680 Leibnitz proposed the theory that the Earth was originally in a molten state. The classification of strata was begun about the middle of the Eighteenth Century. The views of James Hutton (1788), who returned to the theories advanced by Ray (a return to the views of Pythagoras), were continued by Sir Charles Lyell.
Geology and Palæontology have progressed side by side. Among the most famous investigators are Cuvier, Dawson, Marsh, Owen, Huxley, Agassiz, De Blainville, Kaup, Sir Roderick Murchison, Boyd Dawkins, Sir William Flower, R. Lydekker, and E. D. Cope.
To the review of the new developments of meteorologyand the science of probabilities by Sir Ralph Abercromby, on pages 784-792 of Vol. II, it is only necessary to add that the interest in meteorological research developed greatly after Torricelli’s discovery in 1643 of weight and pressure in the atmosphere led to the perfection of the barometer and the development of the thermometer and hygrometer, both in the Seventeenth Century. The theory of trade-winds George Hadley announced in thePhilosophical Transactionsfor 1735. Dalton’sMeteorological Essays, published in 1793, and Dr. William Charles Wells’sTheory of Dew, published in 1814, attracted much attention. Regarding the inquiries into the laws of light by Snell, Newton, Descartes, Thomas Young, and Sir George Airy, the reader is referred to the chapter on The Rainbow in Vol. II, by John Tyndall, with whose researches in the latter half of the Nineteenth Century every one is more or less acquainted.
Little need be said here regarding the history of Botany, which is reviewed on pages 984-1000 of Vol. II. We may add, however, that one of the first to revive this study was Otto Brunsfels, whoseHistoria Plantarum Argentoratiwas published in two folio volumes with cuts in Strasburg in 1530. He had many followers on the Continent and in England. During the revival of learning, chairs of Botany were founded in the universities; botanic gardens were established in many places (theJardin des Planteswas founded in 1626); and botanists began to travel to remote countries to search for unknown flora.
To the Seventeenth Century belong the names of Dr. Turner, “the father of English Botany”; Robert Morison, professor of Botany at Oxford; John Ray, Nehemiah Grew, Malpighi, Henshaw, and Robert Hooke. The two latter were among the first to employ the newly invented microscope to the study of this science. It may be mentioned in passing, that Huygens is said to have taken from Holland to England microscopes about the size of a grain of sand, and that the first microscope consisting of a combination of lenses is attributed to Jansen, a spectacle-maker of Holland.Hooke, whom Herschel calls “the great contemporary and almost the rival of Newton,” gave a tremendous impetus to Microscopy, and practically laid the foundation of Histology or the Inner Morphology of Plants, due to Grew and Malpighi. Schleiden undertook to explain the mysteries of cell formation in 1838, further investigated by Schwann, and is now known as the Schleiden-Schwann theory. Nägeli and Von Mohl continued researches on this line. To the contents of the cell Von Mohl gave the nameprotoplasm.
In 1849, Hofmeister began investigations into the life-histories of plants, since when the study of Vegetable Physiology has progressed side by side with Chemistry. To Darwin great subjects are due: the cross-fertilization of plants, their reproduction, and their relations to insects and their movements. It may be mentioned, however, that in 1693 Ray attempted to explain the movements of leaves, tendrils, and petals by physical and mechanical laws.
Since the middle of the Nineteenth Century, the branches of Botany that have been particularly studied are Vegetable Physiology and Pathology, Inner Morphology, and Fossil Botany—and the discoveries made have naturally had an effect upon the classification of vegetable life.
According to Agassiz:
“We must come down to the last century, to Linnæus, before we find the history taken up where Aristotle had left it, and some of his suggestions carried out with new freshness and vigor. Aristotle had already distinguished between genera and species; Linnæus took hold of this idea, and gave special names to other groups, of different weight and value. Besides species and genera, he gives us orders and classes—considering classes the most comprehensive, then orders, then genera, then species. He did not, however, represent these groups as distinguished by their nature, but only by their range; they were still to him, as genera and species had been to Aristotle, only larger or smaller groups, not founded upon and limited by different categories of structure. He divided the animal kingdom into six classes: Mammalia, Birds, Reptiles, Fishes, Insects, and Worms.”
“We must come down to the last century, to Linnæus, before we find the history taken up where Aristotle had left it, and some of his suggestions carried out with new freshness and vigor. Aristotle had already distinguished between genera and species; Linnæus took hold of this idea, and gave special names to other groups, of different weight and value. Besides species and genera, he gives us orders and classes—considering classes the most comprehensive, then orders, then genera, then species. He did not, however, represent these groups as distinguished by their nature, but only by their range; they were still to him, as genera and species had been to Aristotle, only larger or smaller groups, not founded upon and limited by different categories of structure. He divided the animal kingdom into six classes: Mammalia, Birds, Reptiles, Fishes, Insects, and Worms.”
Linnæus’s classification was, therefore, the first attempt to group animals; but until Cuvier there was no great principle of classification. In 1707 Buffon succeeded in making Zoology, which had been regarded as a most uninteresting study, popular and respected. He also had the idea of collecting all the known facts of scientific investigation and arranging them systematically. Buffon was ridiculed as a scientist by his contemporaries, Hevelius, Diderot, D’Alembert, and Condillac, who opposed his explanations of natural phenomena. Buffon’sHistoire Naturelle Générale et Particulièreis his most important work. A complete edition in thirty-six volumes appeared in Paris in 1749-1788. Although it is said to “have made an epoch in the study of the natural sciences” in Buffon’s day, it now possesses little scientific value.
Cuvier’s classification has never been overthrown. His original investigations in various departments of science, and particularly that of fossil vertebrate animals, opened up new fields of study. His talents with both pen and pencil contributed largely to making that branch of science popular.
Lamarck, Cuvier’s contemporary, divided the animal kingdom into Vertebrates and Invertebrates. Lamarck, like Geoffroy Saint-Hilaire, was a believer in the theory of evolution, which was opposed by Cuvier.
Lamarck turned from the study of Meteorology to that of Botany, and later again to that of Zoology. In 1793 he became professor of the natural history of the lower classes of animals in theJardin des Plantes. His theories have greatly influenced modern science, particularly that of the “Variation of Species,” which was set forth in hisPhilosophie Zoologique(two vols., Paris, 1809) and other works. Lamarck’sHistoire des Animaux sans Vertèbres(seven vols., Paris, 1815-22) is his greatest work.
Karl Ernst von Baer, the Russian naturalist, a pupil of Döllinger in Würzburg, devoted himself chiefly to the study of embryology and made valuable discoveries.
Passing by many illustrious names, we come to that of Sir Richard Owen, of whom it has been said that “from the sponge to man, he has thrown light over every subject he has touched.” His work in the Hunter Museum, his descriptions and restorations of extinct birds and animals, and his original works on every branch of animal life, form an enormous contribution to the progress of science. He promulgated the advanced views of John Hunter, the great physiologist and surgeon, of whose famous museum of more than ten thousand specimens, illustrative of anatomy and natural history, he became curator.
Three names shine with especial lustre upon the Nineteenth Century—Darwin, Huxley, and Spencer. The theory of evolution first appeared in De Maillet’s work,Telliamed, published in 1758, but written in 1735. More than thirty writers before Darwin treated this theory, among whom were Erasmus Darwin, Goethe, Lamarck, and Geoffroy Saint-Hilaire. Largely owing to the opposition of Cuvier, it never succeeded until it was revived by Charles Darwin, who, after twenty-one years of work, published his results in 1858 in theJournal of the Linnæan Society, followed in the next year byThe Origin of Species by Means of Natural Selection(see pages 1482-1512 of Vol. IV).
“The lifeless earth,” says Sir Robert Ball, “is the canvas on which has been drawn the noblest picture that modern science has produced. It is Darwin who has drawn this picture. He has shown that the evolution of the lifeless earth from the nebula is but the prelude to an organic evolution of still greater interest and complexity. He has taken up the history of the earth at the point where the astronomer left it, and he has made discoveries which have influenced thought and opinion more than any other discoveries that have been made for centuries.”
“The lifeless earth,” says Sir Robert Ball, “is the canvas on which has been drawn the noblest picture that modern science has produced. It is Darwin who has drawn this picture. He has shown that the evolution of the lifeless earth from the nebula is but the prelude to an organic evolution of still greater interest and complexity. He has taken up the history of the earth at the point where the astronomer left it, and he has made discoveries which have influenced thought and opinion more than any other discoveries that have been made for centuries.”
The neglected department of Marine Zoology the Nineteenth Century has made particularly its mission to investigate, but space only permits mention of four names: Edward Forbes, Lord Kelvin (Sir Wyville Thomson), Ernst Heinrich Haeckel, and the Prince of Monaco.
The first, whom Lord Kelvin considers “the most accomplished and original naturalist of his time,” was a pupil of Geoffroy Saint-Hilaire, Jussieu, and De Blainville. He is regarded as the originator of the use of the dredge for collecting specimens and the first who undertook the systematic study of Marine Zoology with reference to the distribution of fauna. In 1859 hisNatural History of the European Seasappeared after his death.
One of the most important investigators in this line is Prof. Haeckel, famous for his studies of the lower class of marine animals. He is also distinguished for his researches in other branches of Zoology and Palæontology, and was one of the first followers of Darwin in Germany.
Entomology has also made enormous progress during theNineteenth Century. At the end of the Seventeenth Century, Ray estimated the number of insects throughout the world at 10,000 species! The great entomologists of the Eighteenth Century include Linnæus, De Geer, and Fabricius. Next follow Latreille, Kirby and Spence, and a host of distinguished scientists in Europe and the United States, of whom Sir John Lubbock (Lord Avebury) heads the list. A comparatively new line of investigation is that of the Chalcididæ (see Fairy Flies, pages 1449-1458, in Vol. IV).
ESTHER SINGLETON.