1 58 POPULAR LECTURES. AND ADDRESSES. 



geodesic measurement by Picard which led to a 

 serious correction of the previously accepted 

 estimate of the Earth's radius. This was what 

 Newton required. He went home with the result, 

 and commenced his calculations, but felt so much 

 agitated that he handed over the arithmetical work- 

 to a friend : then (and not when, sitting in a garden, 

 he saw an apple fall) did he ascertain that gravita- 

 tion keeps the Moon in her orbit. 



Faraday's discovery of specific inductive capacity, 

 which inaugurated the new philosophy, tending to 

 discard action at a distance was the result of 

 minute and accurate measurement of electric forces. 



Joule's discovery of thcrmo-dynamic law through 

 the regions of electro-chemistry, electro-magnetism, 

 and elasticity of gases was based on a delicacy 

 of thermometry which seems simply impossible 

 to some of the most distinguished chemists of the 

 day. 



Andrews' discovery of the continuity between 

 the gaaecua and liquid states was worked out bv 

 many ye, irs ..I laborious and minute meaSUFCfl 

 <>f phenomena scarcely sensible to the naked 



