xxiv CONTENTS. 



PAGB 



Positive and Negative Electricity Franklin draws down 

 Electricity from the Sky Invents Lightning-conductors 

 Discoveiy 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 .... 252 



CHAPTER XXX. 



SCIENCE OF THE EIGHTEENTH CENTURY (CONTINUED). 



Calculation of musical Vibrations, Sauveur Experiments on 

 Vibrations of Strings Bernoulli, Euler, Lagrange Four 

 Conditions determining the pitch of a Stretched String The 

 Octave Nodes and Segments in a Vibrating String Over- 

 tones or Harmonics Chladni Discovers Mode of Vibration 

 of Metal and Glass Plates Vibration of Bells and Gongs- 

 Sand Figures produced by Vibration . . . . .263 



CHAPTER XXXI. 



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 

 Measuring 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 La- 

 grange proves the Stability of the Orbits of the Planets Sir 

 William Herschel constructs his own Telescopes Discovery 

 of a New Planet Discoveiy 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 

 Schehallion Experiment Summary of the Science of the 

 Eighteenth Century ........ 275 



