Sir David Brewster, a distinguished physicist, was born at Jedburgh, on December 11, 1781. He was educated at Edinburgh University, and was licensed as a clergyman of the Church of Scotland by the Presbytery of Edinburgh. Nervousness in the pulpit compelled him to retire from clerical life and devote himself to scientific work, and in 1808 he became editor of the "Edinburgh Encyclopaedia." His chief scientific interest was optics, and he invented the kaleidoscope, and improved Wheatstone's stereoscope by introducing the divided lenses. In 1815 he was elected a member of the Royal Society, and, later, was awarded the Rumford gold and silver medals for his discoveries in the polarisation of light. In 1831 he was knighted. From 1859 he held the office of Principal of Edinburgh University until his death on February 10, 1868. The "Life of Sir Isaac Newton" appeared in 1831, when it was first published in Murray's "Family Library." Although popularly written, not only does it embody the results of years of investigation, but it throws a unique light on the life of the celebrated scientist. Brewster supplemented it in 1855 with the much fuller "Memoirs of the Life, Writings, and Discoveries of Sir Isaac Newton."
I.--The Young Scientist
Sir Isaac Newton was born at the hamlet of Woolsthorpe on December 25, 1642. His father, a yeoman farmer, died a few months after his marriage, and never saw his son.
When Isaac was three years old his mother married again, and he was given over to the charge of his maternal grandmother. While still a boy at school, his mechanical genius began to show itself, and he constructed various mechanisms, including a windmill, a water-clock, and a carriage put in motion by the person who sat in it. He was also fond of drawing, and wrote verses. Even at this age he began to take an interest in astronomy. In the yard of the house where he lived he traced the varying movements of the sun upon the walls of the buildings, and by means of fixed pins he marked out the hourly and half-hourly subdivisions.
At the age of fifteen his mother took him from school, and sent him to manage the farm and country business at Woolsthorpe, but farming and marketing did not interest him, and he showed such a passion for study that eventually he was sent back to school to prepare for Cambridge.
In the year 1660 Newton was admitted into Trinity College, Cambridge. His attention was first turned to the study of mathematics by a desire to inquire into the truth of judicial astrology, and he is said to have discovered the folly of that study by erecting a figure with the aid of one or two of the problems in Euclid. The propositions contained in Euclid he regarded as self-evident; and, without any preliminary study, he made himself master of Descartes' "Geometry" by his genius and patient application. Dr. Wallis's "Arithmetic of Infinites," Sanderson's "Logic," and the "Optics" of Kepler, were among the books which he studied with care; and he is reported to have found himself more deeply versed in some branches of knowledge than the tutor who directed his studies.
In 1665 Newton took his Bachelor of Arts degree, and in 1666, in consequence of the breaking out of the plague, he retired to Woolsthorpe. In 1668 he took his Master of Arts degree, and was appointed to a senior fellowship. And in 1669 he was made Lucasian professor of mathematics.
During the years 1666-69, Newton was engaged in optical researches which culminated in his invention of the first reflecting telescope. On January 11, 1761, it was announced to the Royal Society that his reflecting telescope had been shown to the king, and had been examined by the president, Sir Robert Murray, Sir Paul Neale, and Sit Christopher Wren.
In the course of his optical researches, Newton discovered the different refrangibility of different rays of light, and in his professorial lectures during the years 1669, 1670, and 1671 he announced his discoveries; but not till 1672 did he communicate them to the Royal Society. No sooner were these discoveries given to the world than they were opposed with a degree of virulence and ignorance which have seldom been combined in scientific controversy. The most distinguished of his opponents were Robert Hooke and Huyghens. Both attacked his theory from the standpoint of the undulatory theory of light which they upheld.