The Eskimo dog commanded by the Eskimo, is guided solely by voice and whip, the latter be ing from twelve to eighteen feet long. In the hands of the experienced dog runner, the whip becomes a marvelous instrument of precision. He can literally snap the tip of it on a dime(在极小的地方). The Eskimo, unspoiled by white man's influence, is perhaps one of the most trusting and primitive of all Indians but seems to be indifferent to the welfare of his animals. In this he' s simply a product of his environment where food is hard to get, hunger is frequent, and the climate for nine months of the year is marked by bitter cold and a long stretch of darkness. In consequence, his dogs have to earn their keep and earn it the hard way. Rarely is dog taken into the shelter of the family' s home. His sleeping place, no matter how severe the weather, is a burrow(洞穴) in the snow. Rarely is the Eskimo dog permitted to wander. When his master is moved to travel, the dog has to be on hand to help pull whatever load is put on the sledge(雪撬), and often such loads are very heavy. The Eskimo dog in his region is tough, savage, quarrelsome animal with a hairtrigger(一触即发的) temper. On his home ground he re quires stern handling--and he gets it. An Eskimo uses his whip ______.