Double Boiler: Two Tinned Copper Pans, One Hung in the Other

A double boiler, or bain-marie, sets a smaller pan in a larger one of water, so what is inside cannot get hotter than boiling water: chocolate melts without splitting and egg sauces do not curdle. Raise two copper pans as for the saucepan, give the inner one a rolled shoulder that hangs on the outer rim, rivet on handles and tin both. The picture: copper cookware in the kitchen of Bourbilly Castle.