190 LECTURE XX. 



additions to the science of algebra, and the mathematics were soon after 

 enriched by Cavalleri's invention of the method of indivisibles. This 

 method was founded on the principles introduced by Archimedes, it was 

 further improved by Wallis, and it led to the still more valuable invention 

 of the fluxional analysis. 



The laws of collision were investigated nearly at the same time in England 

 by Wren and Wallis, and in France by Huygens. After the discoveries 

 of Archimedes and of Galileo, those of Huygens hold the third place, in the 

 order of time, among the greatest benefits that have been conferred on 

 science. His theory of cycloidal pendulums and his doctrine of central 

 forces were the immediate foundations of Newton's improvements. 



Hooke was as great in mechanical practice and in ingenious contrivance, 

 as Huygens was in more philosophical theory ; he was the first that applied 

 . the balance spring to watches, and he improved the mode of employing 

 pendulums in clocks ; the quadrant, the telescope, and the microscope, 

 were materially indebted to him ; he had the earliest suspicions of the true 

 nature of the cause that retains the planets in their orbits ; and the multi- 

 tude of his inventions is far too great to be enumerated in a brief history of 

 the progress of science. 



The composition of motion, and several other mechanical and optical 

 subjects, are elegantly treated in the lectures published by the learned 

 Doctor Barrow.* He was professor of mathematics at Cambridge, and 

 voluntarily resigned his chair to make way for his successor, the pride of 

 his country, and the ornament of mankind. Sir Isaac Newton t was born 

 at Woolsthorpe in Lincolnshire, on Christmas day in 1642, the year of 

 Galileo's death. At the age of 12 he was sent to school at Grantham, and 

 at 18 to Cambridge. He made some important improvements in algebraical 

 analysis, and laid the foundation of his admirable method of fluxions, 

 before he was 24 years old ; but his modesty prevented him from imme- 

 diately publishing any work on these subjects. His first optical experi- 

 ments were also made in the year 1666, and they were communicated to the 

 Royal Society, then in its infancy, on his admission as a member in 1672. 

 The theory of gravitation, and the mechanics of the universe, are developed 

 in his Mathematical Principles of Natural Philosophy, first published in 

 1687. The following year he was chosen representative of the university 

 of Cambridge in parliament, and in 1696 he was placed, upon the recom- 

 mendation of the Earl of Halifax, in a lucrative situation in the Mint. 

 From 1703 until his death in 1727, he continued president of the Royal 

 Society, and enjoyed, to the age of 80, an uninterrupted state of good 

 health. He was knighted by Queen Anne, in 1705, and died possessed of a 

 considerable fortune. " He had the singular happiness," says Mr. Fonte- 

 nelle, "of obtaining, during his life, all the credit and consideration to which 

 his sublime researches and his fortunate discoveries entitled him. All men 

 of science, in a country which produces so many, placed Newton, by a kind 

 of acclamation, at their head ; they acknowledged him for their chief and 



* Lectiones Mathematics xxiii. Lond. 1685. 



f See Brewster's Life of Newton. A new edition, containing many important 

 facts hitherto unknown, is anxiously expected. Consult also Tumor's Collections 

 for the History of Grantham, 4to, Lond. 1806. 



