Manchester Memoirs, Vol. lix. (191 5), No. 11. 



7 



An equal weight of gold was then placed in the same 

 vessel, and the second overflow likewise measured. It 

 was less than in the case of the crown, and the obvious 

 conclusion was that the crown contained an alloy of some 

 lighter metal. This simple solution of the problem bears 

 the mark of genius, for the reducing of the difficult to 

 terms of the simple is of the essence of genius. 



In 214 B.C. the Roman general Marcellus began the 

 siege of Syracuse, both by sea and by land. Archimedes 

 was then about 73 years of age, but he left his peaceful 

 work and turned his extensive scientific knowledge and 

 unsurpassed ability to the arts of war in the defence of 

 his country. 



He devised for Hiero engines of war which worked 

 havoc among the Roman ships and protracted the siege 

 for three years. Unfortunately we have very little reliable 

 information on the subject of these inventions. It is 

 said that he constructed a burning mirror which set the 

 Roman ships on fire when they were within a bow shot 

 of the wall, and we are also told of a kind of gun which 

 could throw a heavy stone to a great distance by means 

 of steam pressure. It is clear, however, that the ingenious 

 contrivances of Archimedes were really formidable, and 

 caused widespread terror among the Romans. 



In 212 B.C. the city of Syracuse was captured. The 

 town was sacked ; many houses were wrecked, treasures 

 of art were looted or destroyed ; clouds of smoke darkened 

 for a while the blue Mediterranean sky, many citizens 

 were slaughtered, and among them fell Archimedes at 

 the hand of a Roman soldier. Syracuse now became 

 simply one of the provincial cities of Rome's Empire. 



But the science for which Archimedes had lived could 

 not be destroyed. I lis labours had added to human know- 

 ledge and increased human power. Since the fall of Syra- 



