Please accept my apologies if this is has already been discussed (as I'm sure it has). Could you direct me to the answer?

I'm re-reading S&S and have a question about money (this comes up in historical novels, too). Col. Brandon has 2,000 pounds; Miss Morton has 30,000 pounds. What, exactly, does that mean? Do the Colonel's investments, land, etc., yield an income of 2,000? Or is he living off the interest on those pounds? If the latter, how much might that be?

I haven't posted at Pemberley in quite a while, but I lurk here alot for the delightful smart conversation.