These are made in a great variety of form and size, some obtaining the necessary blast by means of bellows, others by rotary fans or blowers; some with a single and others with a double blast; some with, others without hoods; according to the work they are destined for. Fig. 12 illustrates a "Cyclops" circular forge, with a pan 20 in. across, weighing altogether 10G lb., and costing 90s.; this size is only suited for riveting. The blast is produced by a small rotary blower. The square form of pan, 34 in. by 2G in., will beat 2-in. round iron, weighs 2 cwt., and costs 140s. Fig. 13 is a portable forge, the pan consisting of a box made with thin iron plates, 19 in. square and 9 in. high when closed, as shown at B, and capable of containing all the tools accompanying the forge, as well as the bellows and legs. This forge is made by Schallcr, of Vienna, and is much used in the Austrian army. In large forges the tuyere pipe feeding the blast to the fire is rendered more durable by the constant application of a stream of cold water.