272 PROGRESS OF SCIENCE. 



cartes, Newton, Leibnitz, gifted with intellectual power of 

 extraordinary originality, create methods of calculation at 

 once infallible and mighty which will enable men to solve 

 the deepest problems in astronomy, mechanics, and physics. 

 3. Three men of exceptional genius, Galileo, Kepler, and 

 Newton, discover the LAWS OF MOTION, and all of them 

 are found by the immortal Newton to be due to one primary 

 principle the law of GRAVITATION by which the heavenly 

 bodies are ruled. This was the greatest feat of the century 

 and, it may be added, of all times. 4. For PHYSICS, 

 likewise, fresh horizons are opened. The new departure 

 begins with Galileo's discoveries in barology, followed by 

 those of Torricelli, Pascal, Guericke who formulate ATMOS- 

 PHERIC LAWS; then come Huygens, Roemer, and Newton, 

 who investigate the LAWS OF LIGHT; whilst a new power, 

 practically unknown till then ELECTRICITY becomes a re- 

 cognised force through Guericke. 5. PHYSIOLOGY, founded 

 in the previous century, also accelerates its rate of progress, 

 by the beautiful discoveries of Harvey, Malpighi, Rudbeck, 

 Leuwenhoeck, and Swammerdam. In this branch a new 

 world has been revealed through the microscope, neither 

 less wonderful nor less varied than the one discovered by 

 the telescope. The philosophical lesson of the XVIth 

 century is repeated and learnt more earnestly : that is, 

 THE IDEA OF LAW becomes more widely and more deeply 

 rooted, and the recognition of this principle militates against 

 superstition and for truth, with all the vigour which inspires 

 the great thinkers of the end of the XVIIth century. 



III. Expansion. The work of the XVIIth century lies 

 chiefly in the discovery of grand laws. The XVIIIth 

 century presents different features, i. It witnesses in ASTRO- 

 NOMY a VAST ACCUMULATION OF FACTS which at one and 

 the same time corroborates those laws, and extends their 

 application universally. This is the work of W. Herschel, 

 Lagrange, and Laplace. The study of the heavens which 

 Cassini, Bradley, Halley, Flamsteed, Huygens, and Newton 

 had apparently exhausted, was in reality found to be an 

 inexhaustible field of search ; and the XVIIIth century, 

 as indeed the XlXth, showed that the great astronomers 



