ILLUSTRATIONS 



HUYGENS'S CLOCK .... % Facing p. 222 



DIAGRAM TO ILLUSTRATE NEWTON*S LAW OF GRAVITA- 

 TION 238 



BENJAMIN FRANKLIN 286 



STEPHEN HALES'S EXPERIMENT TO DETERMINE THE PRESS- 

 URE OF THE FLOW OF SAP 298 



CAROLUS LINNAEUS " 302 



