This was a round, straight cupola, with an inside air cham ber formed by cast-iron staves shaped to give a bosh at the bottom of the cupola and a taper back from the bosh to the straight' lining. The tuyeres consisted of a series of round open ings of from one inch to three inches in diameter. These were made of cast iron and fastened to the staves by cleats cast upon them. The three-inch openings were placed in a row three or four inches apart around the cupola at a proper height above the sand bottom, a second row of a smaller diameter Was placed over each tuyere in the first row, but only one inch above it, and another of smaller diameter one inch above this, and so on, until six, eight or ten rows were put in, the lower one being. Three inches and the top one one inch in diameter. This tuyere was called the Truesdale reducing tuyere. These tuyeres were placed so closely together that fire brick could not be placed between them, and a plastic cupola daubing was placed between them to serve as a cupola lining.