THE FIRST IDEAS OF GRAVITATION 127 



the circumnavigation of Africa ; though before the Christian 

 era the rotundity of the earth was taught to children throughout 

 the Greek world, and though Strabo had conjectured the exist- 

 ence of " many other habitable places " far beyond the Pillars 

 of Hercules, there was no Greek or Phoenician Columbus to 

 venture across these uncharted wastes they had no " guiding 

 arrow." So, in the same way, there was no great organising 

 brain to put together the geometrical demonstrations of Aris- 

 tarchus, the mechanical constructions of Archimedes, and the 

 conjectures of Anaxagoras, and thus, as it were, disclose the 

 mechanism of the world. They had no reliable measure of 

 seconds, and they lacked a science of dynamics a mechanics 

 of moving bodies. 



The foundations had been admirably laid by Archimedes ; 

 but he seemed to find no followers to carry on his work. The 

 sword which estopped that marvellous brain seemed to strike 

 down not a man but a school ; he had practically no successors. 

 In pure astronomy Hipparchus and Ptolemy made brilliant 

 discoveries ; but there was no further advance toward a 

 mecanique celeste. Though Ctesibius, at Alexandria, could 

 invent suction-pumps and fire-engines ; though his more famous 

 pupil, Hero or Heron, could invent the steam-engine and other 

 marvels, they were of no use, they bore no fruit. 



There was a something in the spirit of the age which was 

 fatal to any advance. The organisation of society into masters 

 and slaves brought just such a contempt of industry as was 

 to be seen in England in the land-owning days, and in the 

 southern States before the war. The whole atmosphere of the 

 time was simply stifling to practical things. Industry, labour, 

 was the vile occupation of slaves ; mechanics, as we see in 

 Plato, was an art despised. Experimental science, almost 

 wholly dependent on mechanical devices, could not flourish. 



Perhaps, too, it would be hopeless to suppose that men 

 would look for, or readily accept, mechanical explanations of 

 phenomena until they had grown accustomed, in their daily 

 lives, to the workings of machinery, and the obvious relations 

 of force and matter, of energy and work. 



After Hero, in a thousand years, you cannot find trace in 

 all Christendom of a new instrument or a new tool. After 

 Ptolemy and Galen the spirit of initiative, of investigation, 

 seemed to disappear. Exhausted by incessant and savage 



