I got the 70 by reading a British Parliamentary paper on the shifting value of the pound since (as I remember) 1750, then using a formula that paper gave. Then I took the pound/dollar exchange rate when I made the caluculation to arrive at 70. Of course, all sorts of things were different--among them servants wages--but knowing how high the approximate number is is much better than multiplying at will by 5, 50 or 100.I think readers like to get a rough idea of how much money was involved, especially when it comes out to figuring who can expect to marry whom.