Kiln. Reconstruction according to Theophilus Presbyter
In his treatise "On various arts", the 11th-12th century Benedictine monk and public figure, Theophilus, describes a kiln that generates high temperatures. This kiln, like the one described by Vakhtang the Sixth, works on the natural draft principle.
As part of the project such a kiln was built and was used both in performing many experiments on glass and in making enamels.