Part 76

Kepler is represented by his biographers as a man of small stature, thin, of a weak constitution, and defective sight; but of somewhat gay and sportive manners. He was attached to his science with the most fervent enthusiasm; he sought after truth with eagerness, but forgot, in the search, the maxims of worldly prudence. To him were allotted but a scanty share of what are commonly esteemed the pleasures of life; but he endured all calamities with firmness, being consoled by the higher enjoyments which science never fails to impart to her true and cordial votaries. ‘As an astronomer,’ says Lalande, ‘he is as famous in astronomy for the sagacious application which he made of Tycho’s numerous observations (for he was not himself an observer), as the Danish philosopher for the collection of such vast materials.’ To him, says another authority, the world is indebted for the discovery of the true figure of the planetary orbits, and the proportions of the motions of the solar system. Like the disciples of Pythagoras and Plato, Kepler was seized with a peculiar passion for finding analogies and harmonies in nature; and though this led him to the adoption of strange and ridiculous conceits, we shall readily be disposed to overlook these, when we reflect they were the means of leading him to the most important discoveries. He was the first who discovered that astronomers had been mistaken in ascribing circular orbits and uniform motions to the planets, since each of them moves in an ellipse, having one of its foci in the sun; and after a variety of fruitless efforts, he, on the 15th of May 1618, made his splendid discovery, that the squares of the periodic times of the planets are always in the same portion as the cubes of their mean distances from the sun. The sagacity of this wonderful man, and his incessant application to the study of the planetary motions, pointed out to him some of the genuine principles from which these motions originate. He considered gravity as a power that is mutual between bodies; that the earth and moon tend toward each other, and would meet in a point so many times nearer to the earth than to the moon as the earth is greater than the moon, if their motions did not prevent it. His opinion of the tides was, that they arise from the gravitation of the waters towards the moon; but his notions of the laws of motion not being accurate, he could not turn his conceptions to the best advantage. The prediction he uttered at the end of his epitome of astronomy, has been long since verified by the discoveries of Sir Isaac Newton; namely, that the determination of the true laws of gravity was reserved for the succeeding age, when the Author of Nature would be pleased to reveal these mysteries.

NEWTON.

The year in which Galileo died, was that in which Isaac Newton was born. This eminent individual, who was destined to establish the truth of the discoveries of his illustrious predecessors, Copernicus and Galileo, was born on the 25th of December 1642, at Coltersworth, in Lincolnshire, where his father cultivated his own moderate paternal property. After receiving the rudiments of education, under the superintendence of his mother, he was sent, at the age of twelve, to the grammar school at Grantham, where the bias of his early genius was shown by a skill in mechanical contrivances, which excited no small admiration. Whilst other boys were at play, his leisure hours were employed in forming working models of mills and machinery; he constructed a water-clock from an old box, which had an index moved by a piece of wood sinking as the drops fell from the bottom, and a regular dial-plate to indicate the hours.

On his removal from school, it was intended that he should follow the profession of a farmer, but his utter unfitness for the laborious toils of such a life was soon manifested. He was frequently found reading under a tree when he should have been inspecting cattle, or superintending laborers; and when he was sent to dispose of farming produce at Grantham market he was occupied in solving mathematical problems in a garret or hay-loft, whilst the business was transacted by an old servant who had accompanied him to town. These strong indications of the bias of his disposition were not neglected by his anxious mother; she sent him again for a few months to school, and on the 5th of June 1660, he was admitted a student of Trinity College, Cambridge.

The combination of industry and talents, with an amiable disposition and unassuming manners, naturally attracted the notice of his tutors, and the friendship of his admiring companions; amongst these was Isaac Barrow, afterwards justly celebrated as a preacher and a mathematician. Saunderson’s Logic, Kepler’s Optics, and the Arithmetic of Infinites by Wallis, were the books first studied by Newton at Cambridge. He read the geometry of Descartes diligently, and looked into the subject of judicial astrology, which then engaged some attention. He read little of Euclid, and is said to have regretted, in a subsequent part of his life, that he had not studied the old mathematician more deeply.

The attention of Newton, while he was pursuing his studies at Cambridge, was attracted to a branch of natural philosophy hitherto little understood――namely, light. It was the opinion of the celebrated philosopher Descartes that light is caused by a certain motion or undulation of a very thin elastic medium, which he supposed pervaded space. Newton overturned this theory. Taking a piece of glass with angular sides, called a prism, he caused the sun to shine upon it through a small hole in the shutter of a darkened apartment. By this experiment he found that the light, in passing through the glass, was so refracted or broken, as to exhibit on the wall an image of seven different tints or colors; and after varying his experiments in a most ingenious way, he established the very interesting facts, that light is composed of rays resoluble into particles, that every ray of white light consists of three primary and differently colored rays (red, yellow, and blue), each of which three is more or less refrangible than the other. This remarkable discovery laid the foundation of the science of optics.

In 1665, the students of the university of Cambridge were suddenly dispersed by the breaking out of a pestilential disorder in the place. Newton retired for safety to his paternal estate: and though he lost for a time the advantages of public libraries and literary conversation, he rendered the years of his retreat a memorable era in his own existence, and in the history of science, by another of his great discoveries――that of the theory of gravitation, or the tendency of bodies towards the center of our globe. One day, while sitting in his garden, he happened to see an apple fall from a tree, and immediately began to consider the general laws which must regulate all falling bodies. Resuming the subject afterwards, he found that the same cause which made the apple fall to the ground, retained the moon and planets in their orbits, and regulated, with a simplicity and power truly wonderful, the motions of all the heavenly bodies. In this manner was discovered the principle of gravitation, by a knowledge of which the science of astronomy is rendered comparatively perfect.

On his return to Cambridge in 1667, he was elected Fellow of Trinity College; and two years afterwards, he was appointed professor of mathematics in the place of his friend Dr. Barrow, who resigned. His great discoveries in the science of optics formed for some time the principal subject of his lectures, and his new theory of light and colors was explained, with a clearness arising from perfect knowledge, to the satisfaction of a crowded and admiring audience. He was elected a Fellow of the Royal Society in 1671, and is reputed to have been compelled to apply for a dispensation from the usual payment of one shilling weekly, which is contributed by each member towards the expenses. He had at this period of life no income except what he derived from his college and professorship, the produce of his estate being absorbed in supporting his mother and her family. His personal wishes were so moderate, that he never could regret the want of money, except as much as it limited his purchases of books and scientific instruments, and restricted his power of relieving the distresses of others. About the year 1683, he composed his great work, _The Principia_, or _Mathematical Principles of Natural Philosophy_. In 1688, the memorable year of the Revolution, he was chosen to represent the university in parliament, and the honor thus conferred on him was repeated in 1701. His great merit at last attracted the notice of those who had it in their power to bestow substantial rewards, and he was appointed warden of the Mint, an office for which his patient and accurate investigations singularly fitted him, and which he held with general approbation till his death. Honors and emoluments at last flowed upon him. Leibnitz, having felt envious of the discoveries of Newton, tried to revenge himself by transmitting a problem, which he thought would show his superiority, by baffling the skill of the English mathematician. It was received by Newton in the evening, after his usual day’s labor at the Mint, and he solved it before he retired to rest. After this there was no further attempt made to traduce his fame. In 1705 he received the honor of knighthood from Queen Anne.

Newton’s benevolence of disposition led him to perform all the minor duties of social life with great exactness; he paid and received frequent visits; he assumed no superiority in his conversation; he was candid, cheerful, and affable: his society was therefore much sought, and he submitted to intrusions on his valuable time without a murmur; but by early rising, and by a methodical distribution of his hours he found leisure to study and compose, and every moment which he could command, he passed with a pen in his hand and a book before him. He was generous and charitable――one of his maxims being, _that those who gave nothing before death, never, in fact, gave at all_. His wonderful faculties were very little impaired, even in extreme old age; and his cheerful disposition, combined with temperance and a constitution naturally sound, preserved him from the usual infirmities of life. He was of middle size, with a figure inclining to plumpness; his eyes were animated, piercing, and intelligent; the general expression of his countenance was full of life and kindness; his sight was preserved to the last; and his hair in the decline of his days was white as snow. The severe trial of bodily suffering was reserved for the last stage of his existence, and he supported it with characteristic resignation. On the 20th of March 1727, he expired at the advanced age of eighty-four years.

The character of Newton cannot be delineated and discussed like that of ordinary men; it is so beautiful, that the biographer dwells upon it with delight, and the inquiry, by what means he attained an undisputed superiority over his fellow-creatures, must be both interesting and useful. Newton was endowed with talents of the highest order; but those who are less eminently gifted, may study his life with advantage, and derive instruction from every part of his career. With a power of intellect almost divine, he demonstrated the motions of the planets, the orbits of the comets, and the cause of the tides of the ocean; he investigated with complete success, the properties of light and colors, which no man before had even suspected; he was the diligent, sagacious, and faithful interpreter of nature, while his researches all tended to illustrate the power, wisdom, and goodness of the Creator. Notwithstanding, also, his reach of understanding and knowledge, his modesty was such, that he thought nothing of his own acquirements; and he left behind him the celebrated saying, ‘that he appeared to himself as only a child picking up pebbles from the shore, while the great ocean of truth lay unexplored before him.’

HUYGENS.

While Newton, in England, was thus enlarging the boundaries of astronomy, and conferring upon it a degree of accuracy and system hitherto unknown, a number of continental philosophers were contributing materials, which, though of an humble character, were not the less necessary to the future progress of the science. First among these was Christian Hüygens, Lord of Zeelhem, born at the Hague on the 14th of April 1629, and descended of a rich and respected family. His father, secretary and counselor to the Princess of Orange, and distinguished as a scholar and poet, was not slow in observing the genius of his son, and, full of paternal solicitude for his improvement, became his first instructor. He early taught him music, arithmetic, and geography――says a writer in the Encyclopædia, from which we select the materials of this notice――and initiated him, when about thirteen, in the knowledge of mechanics, for which the boy had evinced a surprising aptitude. At fifteen, he received the assistance of a master in mathematics, under whose tuition he made great progress; and at sixteen, was sent to Leyden, to study law under the eminent jurisconsult Vinnius. He did not, however, permit jurisprudence to divert him from his mathematical studies, which he now prosecuted with success as well as afterwards at Breda, at the university of which he resided from 1646 to 1648. In these two cities he had respectively as masters two very able geometers, Francis Schooten and John Pell; and his first essays were so successful, that they attracted the notice of Descartes, to whom the author, in his admiration of that great philosopher, had communicated them. Descartes predicted his future greatness, but did not live to appreciate his discoveries.

On quitting the university, Hüygens, as was then the custom, made the tour of Europe; and after his travels, settled in his native country, where he commenced that series of inventions which have rendered his name so justly celebrated. Between the years 1650-60, his pursuits were chiefly mathematical, resulting in several publications of acknowledged merit. In 1655 he traveled into France, and took the degree of Doctor of Laws at Angers; and in 1658 made known his invention of the pendulum clock. In the following year he published his discoveries relative to the planet Saturn; discoveries which inseparably associate his name with the science of astronomy. Galileo had endeavored to explain some of the appearances exhibited by that planet. He had at first observed two attendant stars, but some time afterwards was surprised to find that they had disappeared. Hüygens, desirous to account for these changes, labored with his brother Constantine to improve the construction of telescopes; and having at length made an instrument of this kind, possessing greater power than any which had yet been contrived, he proceeded to observe the phases of Saturn, and to record all the different aspects of that planet. The results were of equal interest and importance to the science of astronomy. He discovered a satellite of that planet which had hitherto escaped the notice of astronomers; and after a long course of observation, he showed that the planet is surrounded by a solid and permanent ring, which never changes its situation. In 1660 he took a second journey into France; and the year following he visited England, where he communicated the art of polishing glasses for telescopes, and was admitted a member of the Royal Society. The air-pump, then recently invented, he materially improved; and about the same time he also discovered the laws of the collision of elastic bodies, as did afterwards Wallis and Wren, who disputed with him the honor of the discovery. After a stay of some months in England, Hüygens returned to France, where, in 1633, his merit became so conspicuous, that Colbert resolved to bestow on him such a pension as might induce him to establish himself at Paris. This resolution was not carried into effect until 1665, when letters in the king’s name were written to the Hague, where the philosopher then resided, inviting him to repair to Paris, and offering him a considerable pension, with other advantages. Hüygens accepted the proposal; and from 1666 to 1681, settled at Paris, where he was admitted a member of the Royal Academy.

During this period he was chiefly engaged in mathematical pursuits: he wrote and published several works, which were favorably received; and he invented and improved some useful instruments and machines. By continued application, his health began to be impaired, and he at length found it necessary to return to his native country――a step somewhat accelerated by the revocation of the Edict of Nantes, which rendered him liable to molestations, although assured of the fullest privilege to follow his own religious opinions. He accordingly left the French metropolis in 1681; passed the remainder of his days in his own country, and in the pursuit of his favorite subjects; and died at the Hague on the 8th of June 1683, in the sixty-seventh year of his age. ‘This illustrious man,’ continues our authority, ‘gave his whole time to science; he loved a quiet studious life, and found sufficient enjoyment in pursuing curious and useful researches. He was modest, amiable, cheerful, and in all respects as estimable in private life as he was eminent in science. It is not a little singular that the discovery of the real nature, or at least of the true figure, of the luminous ring which encompasses the planet Saturn, should have been made by the same individual who invented the pendulum clock and the micrometer.’ His inventions, however, were more of a mathematical and mechanical than of an astronomical character; and we safely predict, that had Hüygens lived in the present day, he would have risen to superlative fame as a mechanician and engineer.

HALLEY.

Dr. Edmund Halley, a name well known in the annals of astronomy, was the only son of a soap-boiler in London, and was born in 1656. He received the rudiments of his education at St. Paul’s School in his native city; and in his seventeenth year, became a commoner in Queen’s College, Oxford. At first he applied himself to the study of the languages and sciences, but at length gave himself wholly up to that of astronomy; and before he had attained his nineteenth year, published a method of finding the aphelia and eccentricity of planets, which supplied a defect in the Keplerian theory of planetary notions. By some observations on a spot on the sun’s disk in the summer of 1676, he established the certainty of the motion of that body round its own axis; and in the same year fixed the longitude of the Cape of Good Hope, by his observations of the occultation of Mars by the Moon. Immediately after, he went to St Helena, where he staid till 1678, completing a catalogue of the fixed stars of the southern hemisphere, which was published in the following year, and gained for its author the appellation of the ‘Southern Tycho.’ In 1679 he was called upon to settle a dispute between the English philosopher Hooke and the celebrated Hevelius, respecting the use of optical instruments in astronomy, and for this purpose went to Dantzic, where with honorable impartiality, he decided against his own countryman. In 1680 he made the tour of Europe, making the acquaintance of Cassini at Paris, and completing his observations from the Royal Observatory of France on the comet which now bears his name. After spending the greater part of 1681 in Italy, he returned to England, and settled at Islington, where he fitted up an observatory for his astronomical researches.

In 1683 he published his Theory of the Variation of the Magnetical Compass, in which he endeavored to account for the phenomenon, by the supposition of the whole globe being one great magnet, having four circulating magnetical poles or points of attraction. His theory, though unsatisfactory, is ingenious. The doctrines of Kepler relative to the motions of the planets next engaged his attention; and finding himself disappointed in his endeavors to obtain information on the subject from Hooke and Sir Christopher Wren, he went to Cambridge, where Newton, then mathematical professor, satisfied his inquiries. In 1691 he was candidate for the Savilian professorship of astronomy at Oxford――a chair which he would have obtained, had he not refused to profess his thorough belief in all the doctrines of the Christian religion, as taught by the church of England. For the purpose of making further observations relative to the variation of the compass, he set sail on a voyage in 1699 (having obtained the command of a vessel from King William, who was anxious to promote the cause of geographical and astronomical science); and after traversing both hemispheres, and making important observations at numerous stations, he returned to England in September 1700. As the result of his researches, he published a general chart, showing at one view the variation of the compass in all those seas where the English navigators were acquainted; and thus laid the foundation of that department of science which has since received the attention of the greatest philosophers. His next employment, under the patronage of the king, was to observe the tides in the English Channel, with the latitudes and longitudes of the principle headlands; observations which were shortly after published in a large map of the Channel. In 1703, he was engaged by the emperor of Germany to survey the coast of Delmatia; and returning in November of that year to England, he was elected Savilian professor of geometry on the death of Dr. Wallis, and was also honored with the diploma of LL.D.; a title somewhat more in consonance with his pursuits than that of ‘Captain,’ by which he had been styled from the time of his appointment to the command of the surveying vessel furnished him by King William. Dr. Halley now gave his mind more entirely to mathematics, translating into Latin from the Arabic and Greek several treatises, which he afterwards published with supplementary matter, such as those of Appolonius and Serenus.

In 1719 he received the appointment of astronomer-royal at Greenwich, where he afterwards chiefly resided, devoting his time to completing the theory of the motion of the moon, which notwithstanding his age, he pursued with enthusiastic ardor. In 1721 he began his observations, and for the space of eighteen years, scarcely ever missed taking a meridian view of the moon when the weather was favorable. He died at Greenwich in 1742, at the advanced age of eighty-six, having spent one of the most active and useful lives on record. His honors and titles were numerous, but no more than his multifarious occupations and achievements entitled him to. In all he exhibited the same promptness of resolve and incessant assiduity, willing to assist or be assisted; and never deigning it beneath him to confess when ignorant, nor to receive information from any quarter, however humble. Whether as Captain Halley, as secretary to the Royal Society, consulting engineer to the emperor of Germany, or astronomer-royal, he was the same ardent, prompt, and indefatigable laborer. His publications and papers were numerous; he gave important assistance to Dr. D. Gregory in the preparation of the conic sections of Appolonius; and to Halley are we also indebted for the publication of several of the works of Sir Isaac Newton, who had a particular friendship for him, and to whom he frequently communicated his discoveries.

FERGUSON.