Said to have been first tried in 1841 by an engineer named Hall as a way of obtaining smokeless combustion of coal. Previously, engines had burned coke or (in the US) wood. It is also said to have been used on the Scottish North Eastern Railway by Thomas Yarrow in about 1857. It was patented in the US in 1857. It finally became universally accepted in Britain after its introduction on the Midland Railway, together with the firehole deflector plate in 1859. The brick arch is located in the firebox over the grate and is attached to the forward firebox wall and the side walls. Its purpose is to deflect the gases rising from the grate towards the back of the firebox so as to keep them over the heat source as long as possible before they pass up into the boiler tubes. This ensures that more complete combustion takes place and that as little unburned smoke as possible escapes through the chimney.