( 34^ ) 
The Third Scflionc 
Refrefentlng the Ufesof this Infirumm as rtktingto 
\Mttds. 
THere is in the nature of the thing fuch a Conneftion be- 
tween the Fabrick and Ufe of our Inftrument, that I could 
not well defcribeit without plainly intimating the Principal 
ufesof it. Wherefore I fliall here but fummarily repeat thofe 
that are delivered already, and make a more explicit mention of 
thofe few, that have been either omitted , or but lightly 
touched. 
The L life^ 
Thefirftufe, and that which was mainly intended , is^, 
cafily and cheaply to difcriminate true Guinys from counter- 
feit , without defacing or any ways injuripg the Coin* But of 
this ufe I have fpoken largely enough already, and therefore fliall 
advance to the next. 
Then, Ufe. 
Any other kind of Gold-Coin that is near about the weight 
ofd^Gumy^ may be examined by our Inftrumenr after the manner 
above delivered 5 but more eafily, if it want of the weight of a 
Guiny than if it exceed it. For in cafe it be heavier, as is a 
Twenty fliiliing piece of broad Gold, the Ballaft, whether in- 
ternal or external, of the Inflrument muft be taken off, that fo 
heavy a Coin may not quite fink it \ whereas, if the Coin pro- 
posed be lighter than a Guiny, one may add as much Gold (of the 
fame alloy) besten into thin plates, as,with the Coin proposed, 
will make up in the Air the weighi of a Guiny, For then this 
aggregate, being examin'dasificwereaGuiny, willdifcovcr m 
the 
