In his “Decline and Fall of the Roman Empire” Edward Gibbon often converts sums denominated ancient roman currency to his own “modern” currency (c.1776 British Pound Sterling). What method did he use for his conversions? We’re they considered accurate at the time, and how well have they held up?

by gowen2TN

Hey /r/askhistorians, basically what the title says.

An example of one of the frequent times he makes this conversation in Decline and Fall of the Roman Empire, Ch. 6 when Gibbon -- in a section describing the increased tax revenue brought in by Caracalla’s edict granting universal citizenship -- says:

"We are informed that, by the conquests of Pompey, the tributes of Asia were raised from fifty to one hundred and thirty-five millions of drachmas; or about four millions and a half sterling"

Google Books source

Another is shortly after that in the same chapter:

"From the faint glimmerings of such doubtful and scattered light, we should be inclined to believe, 1st, that (with every fair allowance for the difference of times and circumstances) the general income of the Roman provinces could seldom ammount to less than fifteen or twenty millions of our money"

Google Books source

Thanks!

EDIT: Is comparing ancient and modern currency even feasible?

Searocksandtrees

OP, just a quick note: I've approved this post, but note for future reference that using shortened links will cause posts to be caught in the Reddit site-wide spam filter.