Holes are bored or drilled to any depth by either of two methods: A drill with a wedge-shaped steel point is raised and let fall by steam power, its own weight driving it down while it is turned part way round at each drop to make the bore round. At intervals of a few hours an iron tube is let down to draw up the mud and water. By the other method the drill is a short tube with rough diamonds set in the lower edge, which cut down into the rock while the drill is revolved by the machinery. This drill brings up a core from the strata penetrated, and is most used for prospecting. The largest bore so far has been 12 inches in diameter and deepest about 3,000 feet. In low lands water is often obtained that gushes up with great force several feet above the surface; these are called flowing wells. In most large or medium-sized cities parties can be found who take contracts for sinking wells where wanted. Artesian wells get their name from Artesium, the ancient name of Artois in France, where these methods began to be used about 150 years ago.