There are a decent number of houses dating from 1735-1800 locally (we're in Ashland, MA, there are a couple houses of similar age, and right next door in Hopkinton there are quite a few).
We have a sporadically updated blog here:
http://1740house.wordpress.com/
I've filled a Nalgene bottle with hot water for my wife a few times when she's sitting on the couch...it's a good way to warm up. I actually bought up a soapstone bed heater at an antique store this summer. It's just a slab of soapstone maybe 12x6x1 with a wire handle. They'd be set in front of the fireplace to warm up during the evening then taken to bed at night to warm it up. I have yet to use it for its original purpose though.