Sometimes an island can be used for a farm even when it has opposite shores or islands within two hundred feet or less, provided the water surrounding it has an average depth of from four to six feet. In such a case, the walls inclosing the island should be built in the water at a distance of fifty or one hundred feet from its shores. Sheets of metal should be used, as previously described, by placing them upright in the water and nailing them together with strips running along the outside. It is not essential that the lower wall should be in the ground or even touching it; posts can be driven in the ground to strengthen the wall, or to support it entirely. [Illustration: A Mink Farm Made Out of an Island. The Water Surrounding Has a Uniform Depth of Five Feet.] In a small farm where minks are in close captivity and have to be fed, the old ones used for the purpose of stocking it will at first do considerable digging near the walls. They will dig into loose earth to a depth ranging from a few inches to three feet in their attempts to liberate themselves. But they will cease to dig after they have been in captivity for about four months. Those born in a farm will not dig or try to get out. They will climb, however, to a height of fifteen feet on reclining trees or on bushes, and for this reason all trees, bushes and pieces of lumber should be removed from the inside of the walls before any minks are turned loose in a farm. They will ordinarily jump to a height of four feet. They can climb wooden walls as swiftly as a cat, or any wall made of soft material. [Illustration: Disturbed in Her Sleep. Notice the Bushy Tail.]