Like in the previous chapter, the use of cams is described in some ancient machines that require alternating motion. Attention is focused on bellows, hammers, and pumps. As with the machines discussed in Chap. 3 , we can observe improvements over time, but no changes in the overall scheme: a follower moves alternately due to a camshaft driven by a water wheel. In metallurgical processes, achieving the required high temperature requires the use of powerful blowing devices, i.e. large bellows. In the Middle Ages, this was achieved with water wheels and camshafts. To overcome the force and energy limitations of hand-operated hammers, the water wheel and camshaft were introduced in the Middle Ages as part of the general mechanization process. The hammers were of the lever type, easily operated by a camshaft. Since ancient times, technology has been faced with the great challenge of lifting water. In this field, too, cams have played an important role, although much less decisive than in the other cases considered so far. It should be noted that a positively controlled cam was first proposed for use in a pumping device in 1588.