In the course of his excavations Artis discovered a singular furnace,[[3147]] “of which I have never before or since met with an example. Over it had been placed two circular earthen fire vessels (or cauldrons); that next above the furnace was a third less than the other, which would hold about eight gallons. The fire passed partly under both of them, the smoke escaping by a smoothly-plastered flue, from seven to eight inches wide. The vessels were suspended by the rims fitting into a circular groove or rabbet, formed for the purpose.” He was strongly of opinion that this furnace was used for producing glazed wares by means of iron oxide. Whether this is so or not, it is interesting to note that in the British Museum and Museum of Geology there are cakes of vitreous matter from Castor, probably used as a glaze, and consisting of silicates of soda and lime.[[3148]]
The kiln found at Caistor, in Norfolk, was apparently used for baking the grey Roman ware, and differed in form from those described, which were for the black, being only calculated for a slight degree of baking. It was a regular oval, measuring 6 feet 4 inches in breadth. The furnace holes were filled in below with burnt earth of a red colour, and in the upper part with peat; the exterior was formed of strong blue clay of 6 inches in thickness, and the interior lined with peat; the kiln was intersected by partitions of blue clay. Some of the vases were inverted and filled with a core of white sand.[[3149]]
FIG. 214. PLAN OF KILN AT HEILIGENBERG.
The furnaces at Heiligenberg and Rheinzabern present the following further peculiarities.[[3150]] The former, which were evidently used for the baking of red wares, had a flue in the form of a long channel with arched vault, the mouth being over 8 feet from the space where the flames and heat were concentrated under the oven (Fig. [214]). Numerous pipes of terracotta, of varying diameter, diverged from the upper part or floor of the oven, to distribute the heat; in the outer wall of the oven was a series of smaller ones, and twelve or fifteen of larger size opened under the floor of the oven to distribute the heat and flame round the pots (Fig. [215]). The mouths of the pipes were sometimes stopped with baked clay stoppers to moderate the heat. The upper part or dome of the kiln is never found entire, having been generally destroyed here, as elsewhere, by the superincumbent earth. Walls of strong masonry separated and protected the space between the mouth of the flue and the walls of the oven, and the floor of the latter was made of terracotta tiles.
FIG. 215. SECTION OF KILN AT HEILIGENBERG.
At Rheinzabern, where excavations were made in 1858, fifteen furnaces were found, some round and others square, but all constructed on the same plan. The floor of the oven was over 3 feet below the top of the walls, and was covered with tiling, the walls being formed of rough slabs of clay, about 28 by 16 inches in size. The floors of the ovens were in some cases supported by bricks covered with a coating of clay. Stands of baked clay in the shape of flattened cylinders supported the pots in the oven, and these rested on pads of a peculiar form, roughly modelled in clay.[[3151]] In all, seventy-seven pottery-kilns and thirty-six tile-kilns were discovered on this site.[[3152]]
The following list, though by no means claiming to be exhaustive, gives the names of the chief potteries where actual furnaces have been discovered.
| 1. Italy | |
| Arezzo | See p. [479] ff. |
| Marzabotto | Mon. Antichi, i. p. 282. |
| Modena | Bull. dell’ Inst. 1875, p. 192. |
| Oria | Ibid. 1834, p. 56. |
| Pompeii | Mau-Kelsey, Pompeii, p. 386. |
| Pozzuoli | Bonner Jahrb. xcvi. p. 54. |