BOOK VII. 



The gth needle of 15 duellae of silver and 9 duellae of gold. 



255 



II 



II 



II 

 II 



II 

 II 



II 

 II 



10 

 ii 



12 

 13 

 14 

 15 



16 



17 

 18 



19 



20 

 21 

 22 

 23 



II 

 II 

 II 

 II 



II 

 II 



II 

 II 







l> 



pure gold 



By the first eleven needles, when they are rubbed on the touchstone, we 

 test what proportion of gold a bar of silver contains, and with the remaining 

 thirteen we test what proportion of silver is in a bar of gold ; and also what 

 proportion of either may be in money. 



Since some gold coins are composed of gold and copper, thirteen needles 

 of another kind are made as follows : 



