How does an Eskimo keep himself warm? Arctic Expert Vilhjalmur Stefansson, in Natural History, explains: he fits his jacket tight around his neck and wears nothing but pants underneath. Dressed in clothing that follows this plan, an Eskimo is comfortable at 40° below. A Minnesotan, who wears three times as much clothing, says Stefansson, is rarely happy outdoors at this temperature.

The reason for the Eskimo's comfort in below-zero weather is that his clothes are not built on the European principle of insulating the body with many layers of cloth fitting close to the...