The question of how to make mulled wine comes up every now and then. I ran
into this recipe in a book "Christmas in the Old West" by Sam Travers and
thought I might share it.

Mulled Wine: Grate one half Nutmeg into a Pint of Wine and Sweeten to your
Taste with Loaf-sugar. Set it over the fire and when it boils take it off
the fire to cool. Beat the yolks of four eggs very well, strain them and
add to them a little cold wine, them [sic] mix them with hot wine gradually.
Pour it backward and forward several times till it looks fine and light,
then set it on the fire and heat it very gradually till it is quite hot and
pretty thick and pour it up and down several times. Put it in chocolate cups
and serve it with long narrow toast. (1801)