BOOK VII. 



255 



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



loth 

 nth 

 i2th 

 13th 

 14th 

 15th 

 i6th 

 17th 

 i8th 

 19th 



20th 

 2ISt 



22nd 

 23rd 

 24th 



14 

 13 

 12 

 II 

 10 



9 

 8 



7 

 6 



5 

 4 

 3 

 2 



I 



10 

 II 

 12 

 13 

 14 

 15 

 16 



17 

 18 



19 

 20 



21 



22 



23 



pure gold 



By the first eleven needles, when they axe 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 : — 



