Room in which Newton was born.
The house of Newton at Woolsthorpe, now the homestead of a farmer, has been in the ownership of persons anxious to protect it, and preserve every relic of its former occupant. Stukeley thus described it in 1727: “’Tis built of stone, as is the way of the country hereabouts, and a reasonable good one. They led me upstairs, and showed me Sir Isaac’s study, where I suppose he studied when in the country in his younger days, or perhaps when he visited his mother from the university. I observed the shelves were of his own making, being pieces of deal boxes which probably he sent his books and clothes down in on those occasions.” Two sun-dials remain which he made when a boy; but the styles of both are wanting, and one has been recently taken from the wall to be presented to the Royal Society. The room in which he was born has the following inscription upon a tablet of white marble: “Sir Isaac Newton, son of John Newton, Lord of the Manor of Woolsthorpe, was born in this room on the 25th of December, 1642.” The apple-tree, the fall of one of the apples of which, according to tradition, drew his attention to the subject of gravity, was blown down by a gale some years ago, and a chair was constructed out of its timber. The Royal Society of London possesses his telescope; the Royal Society of Edinburgh the door of his book-case; and Trinity College, Cambridge, has a lock of his silver white hair.
While the foundations of physical astronomy were laid by Newton, his confidant and friend, the brilliant and active Halley, pursued a remarkably successful career in the practical departments of the science. Born in mercantile life, yet independent of it through the wealth amassed by his father, he early embarked his means and energies in the advancement of observation. Leaving Hevelius and Flamstead to keep guard over the northern hemisphere, he sailed to St. Helena to inspect the southern; and in honor of the reigning monarch who patronized the expedition, the oak which had screened him from his pursuers after the battle of Worcester, was raised to a place in the skies, forming the constellation Robur Carolinum. The object of the voyage was to determine the absolute and relative positions of the stars invisible to the European eye; but owing to the unpropitious climate of the island, only a catalogue of 360 was made after more than a year’s residence. Upon this voyage the oscillations of the pendulum were observed to decrease in number as the instrument approached the equator; a fact noticed a few years previous by Richer, and explained by Newton to result from the greater intensity of centrifugal force there, proportionably diminishing the force of gravity. The life of Halley was remarkable for locomotion, devoted to various scientific objects. He was twice at St. Helena, twice in the Adriatic, once in the West Indies, now with Newton in his study at Cambridge, anon with Hevelius in his observatory at Dantzic, and then with Cassini watching a comet at Paris. Upon the death of Flamstead, he succeeded to the office of astronomer royal, and though then in the sixty-fourth year of his age, he commenced the observation of the moon through a complete revolution of her nodes, involving a period of nineteen years, and lived to finish it, registering upward of two thousand observed lunar places. It was while journeying in France toward the close of 1680, that he observed the great comet of that year, on its return from proximity to the sun: and being aware of the conclusion of Newton, that such bodies describe very eccentric ellipses, his active mind began to study intently their phenomena, which resulted in a prophecy that has immortalized his name. After cataloguing and comparing a considerable number of comets, that of 1682 fortunately appeared. This he was led to regard as identical with those of 1456, 1531, and 1607, between which there is nearly the same interval. Hence he anticipated its return after the lapse of a similar period. “I dare venture,” said he, “to foretell that it will return again in 1758;” and, sanguine as to the result, he called upon posterity to notice that it was an Englishman who had hazarded the statement. This was a prediction announced in 1705, the accomplishment of which ranks with the greatest achievements of modern astronomy, and will perpetuate the fame of Halley to the remotest generations. He had been gathered to his grave in Lee church-yard seventeen years, when the celestial traveler re-appeared, at the time announced, to verify his words, illustrate his sagacity, and invest him with undying honor.
Halley’s Tomb.
Bradley, the English Hipparchus, the model of observers, as he is styled by Laplace, became the third astronomer royal upon the death of Halley. He had previously effected one of his two great discoveries, the aberration of the stars, an optical illusion, arising from the combined movement of the earth in space, and the progressive transmission of light; a discovery of the highest importance, requiring the greatest precision of observation to detect. Ever since the doctrine of the earth’s translation in space had been received, astronomers had been anxious to find some parallax of the fixed stars, as a sensible confirmation of the fact. Although the whole diameter of the earth’s orbit is relatively insignificant, it is yet absolutely vast. Hence it was deemed no unreasonable expectation that some small apparent change of place in the heavens would be discerned in the case of the fixed stars, when viewed from the two extremities of the earth’s annual orbit—separated from each other by the mighty chasm of a hundred and ninety millions of miles.
Aberration, or wandering, is the name given to this phenomenon. The term is not strictly accurate, as the apparent movements thus denominated are not irregular, but uniform. To discover the physical cause became an object of intense interest to Bradley, but it long baffled his researches and reasonings, and was at length developed by an accidental circumstance. He was accompanying a pleasure-party in a sail on the river Thames. The boat in which they were was provided with a mast which had a vane on the top of it; it blew a moderate wind, and the party sailed up and down the river for a considerable time. Bradley remarked, that every time the boat put about, the vane at the top of the mast shifted a little, as if there had been a slight change in the direction of the wind. He observed this three or four times without speaking; at last he mentioned it to the sailors, and expressed his surprise that the wind should shift so regularly every time they put about. The sailors told him that the wind had not shifted, but that the apparent change was owing to the change in the direction of the boat, and assured him that the same thing invariably happened in all cases. From that moment he conjectured that all the phenomena of aberration he had observed, arose from the progressive motion of light combined with the earth’s motion in its orbit. This sagacious conjecture satisfactorily explains the apparent movement of the stars. Suppose a body to pass from A to B in the same time that a ray of light passes from C to B. Owing to the two motions, the impression of the ray of light meeting the eye of a spectator at B will be exactly similar to what it would have been if the
eye had been at rest at B, and the molecule of light had come to it in the direction D, B. The star, therefore, whose real place is at C, will appear at D to the spectator at B. This effect is precisely analogous to what takes place when a person moves or travels rapidly through a shower of rain or snow in a perfectly calm state of the atmosphere. Without locomotion the rain-drops or snow-flakes will fall upon his hat, or upon the head of the carriage that conveys him, and not beat in his face, or against the front windows of the carriage. But if he is passing along swiftly, in any direction, east, west, north or south, the rain or snow will come in contact with his face, or enter the front windows of the carriage if they are open, as though the drops or flakes fell obliquely, and not from the zenith. Now as an object appears to us in the direction in which the rays of light strike the eye, it is easy to understand that a star in the zenith will appear at a little distance from it, to a spectator carried along with the earth in its orbit. This discovery established the fame of Bradley, who was exonerated from all future payments to the Royal Society on account of it; and it is of great importance, as the only sensible evidence we have of the earth’s annual motion. Soon after his appointment to the Greenwich observatory, he effected his second great discovery, that of the nutation of the earth’s axis, a slight oscillation of the pole of the equator about its mean place, describing an ellipse in the period of eighteen years. He determined likewise its cause, which theory had previously inferred to be the action of the moon upon the equatorial regions of the earth. Some idea of his industry may be formed from the fact, that in conjunction with his nephew, he made no less than eighteen thousand observations in a single year while astronomer royal; and the number from the year 1750 to 1762 amounted to upward of sixty thousand. The death of Bradley was interpreted as a Divine judgment by the populace. He had taken an active part with the Earl of Macclesfield and others, in urging on and assimilating the British calendar to that of other nations. This rendered it necessary to throw eleven days out of the current year in the month of September 1752—a measure which the ignorance of great numbers of the people led them to regard as an impious intermeddling with the Divine prerogative. Lord Macclesfield’s eldest son, at a contested election for Oxfordshire, was greeted with the cry from the mob, “Give us back the eleven days we have been robbed of!” and Bradley’s mortal sickness, some years later, was viewed as a punitive dispensation for having participated in the sacrilegious theft.