Gronovius's estimate of the value of Roman money is vitiated by two principal errors: his doctrine that 100 denarii went to the pound weight of silver, a doctrine connected with his theory that the proper and direct meaning of sestertium is two pounds and a half of silver, but which is contradicted both by testimony and by the denarii, which like the bricks in Richard II. are alive to this day to witness to the contrary; and his confounding the pound Troy with the Roman pound. The errors tend to balance, one making the denarius too little in value, and the other making our currency of too small value: but his result is of course mere haphazard, to say nothing of his neglecting the question of alloy.
The basis of the calculations in the Dictionary of Antiquities is much more satisfactory, but the calculations themselves are wrong. The articles Sestertius and Denarius do not take into account that our shilling circulates as a counter above its intrinsic value. The value of the denarius is determined by comparing its weight of fine silver with that of the shilling. Now as our coinage since 1816 is at the rate of 66s. to the pound, the result is the same as if the price of silver had been taken to be 66d. per ounce standard, which certainly is not its real price. The rate of coinage was purposely fixed above the variations of the bullion market to prevent melting. Sixty-two pence is the price commonly assumed in calculating the par of exchange, and is rather a large average price. Taking the data given in the article Denarius, and this price of silver, the denarius of the end of the Republic is worth (not 8.6245d. as it is there made) but 8.099d., or in round numbers not 8½d. but 8d.
The error will be nearly the same in the value of the later denarius.
The value of the sestertium resulting from the value of the denarius which I have quoted is £8. 19s. 8d., though by some error of calculation it is reduced to £8. 17s. 1d.; the real value is £8. 8s. 8½d., so that the two mistakes, like Gronovius's, tell against one another.
