One of three such arches, this opening routed hot blast air to the furnace. Simulated piping has been installed here to show how it could have looked when the furnace was in operation. The piping basically consisted of a main pipe from the oven. Because the oven was usually located on top of the furnace, this pipe was called the downcomer. At Beckley, the oven was on the hill east of the furnace stack, and the downcomer entered the furnace through the east arch. The downcomer fed a semicircular horizontal pipe called the bustle pipe, which carried air to each tuyere arch. The simulated piping here shows the end of the bustle pipe entering from the right. Since the blast air was about 800 degrees, this arch would not have been a comfortable place when the furnace was operating. During the life of this furnace, different tuyere arrangements were used. It is likely that only a single tuyere was included in the original 1847 design, and the simulated piping here shows that single-tuyere arrangement. Later the furnace had a total of 5 tuyeres, with two in this arch, two in the arch opposite it, and one in the large rear arch. Although the exact piping for that later configuration is unknown, examples from other sites suggest what it may have looked like. This area also served as the exhaust for a ventilation system under the hearth, allowing air to circulate and venting gas or steam that might build up, keeping the hearth cooler and preventing explosions. The ventilation system was discovered when the furnace was restored.