CONTENTS. xix 



CHAPTER XXIX. 



SCIENCE OF THE EIGHTEENTH CENTURY (CONTINUED). 



PAGE 



Benjamin Franklin, born 1706— His Early Life — Du Faye dis- 

 covers two kinds of Electricity — Franklin proves that Electricity 

 exists in all Bodies, and is only developed by Friction — Positive 

 and Negative Electricity — Franklin draws down Electricity from 

 the Sky — Invents Lightning-conductors — Discovery of Animal 

 Electricity by Galvani— Controversy between Galvani and Volta 

 — Volta proves that Electricity can be produced by the Contact 

 of two Metals — Electrical Batteries — The Crown of Cups — The 

 Voltaic Pile 2.^1 



CHAPTER XXX. 



SCIENCE OF THE EIGHTEENTH CENTURY (CONTINUED). 



Bradley and Delisle, Astronomers— Aberration of the Fixed Stars 

 — Nutation of the Axis of the Earth, Delisle's Method of Mea- 

 suring the Transit of Venus — Lagrange and Laplace — Libration 

 of the Moon accounted for by Lagrange — Laplace works out the 

 Long Inequality of Jupiter and Saturn — Lagrange proves the 

 Stability of the Orbits of the Planets— Sir William Herschcl 

 constructs his own Telescopes— Discovery of a New Planet — 

 Discovery of Binary Stars — Herschel studies Star-clusters and 

 Nebulae — Theory of Nebulae being matter out of which Stars 

 are made — The Motion of our Solar System through Space — 

 Weight of the Earth determined by the Schehallien Experiment 

 — Summary of the Science of the Eighteenth Century . . 265 



CHAPTER XXXL 



SCIENCE OF THE NINETEENTH CENTURY. 



Difficulties of Contemporary History — Discovery of Asteroids and 

 Minor Planets between Mars and Jupiter — Dr. Olbers suggests 

 they may be fragments of a larger Planet — Encke's Comet, and 

 the correction of the size of Jupiter and Mercury — Biela's 

 Comet, noticed in 1 826 — It divides into two Comets in 1845 — 



