The situation of the potteries was well chosen for carrying on an extensive trade with distant parts of the kingdom, and from researches searches which were made, the late Mr. Artis, to whom the discovery is due, computed that probably two thousand people had been employed in the fabrication of fictile vessels. It is on the line of one of the most important of the Roman roads--the Ermyn street--and close to the navigable river Nen; and that the products of the manufactory were supplied to places throughout the kingdom is abundantly testified by the remains which are almost invariably found in course of excavations wherever Roman occupation is known. Mr. Artis unfortunately, although he published a fine folio volume of plates[6] of the more remarkable of the objects he discovered, never issued the descriptive and historical text which was intended to accompany it. The great bulk of the information he had gleaned he never committed to paper, and consequently it died with him. Mr. Artis, however, communicated some valuable particulars to Mr. C. Roach Smith, and these have been made public by him in the “Journal of the British Archæological Association”[7] and in the “Collectanea Antiqua.”[8] Mr. Artis in one of these says that during an examination of the pigments used by the Roman potters of Castor and its neighbourhood, he was “led to the conclusion that the blue and slate-coloured vessels met with here in such abundance were coloured by suffocating the fire of the kiln at the time when its contents had acquired a degree of heat sufficient to insure uniformity of colour. I had so firmly made up my mind on the process of manufacturing and firing this peculiar kind of earthenware, that I had denominated the kilns in which it had been fired “smother kilns.” The mode of manufacturing the bricks of which these kilns are made is worthy of notice. The clay was previously mixed with about one-third of rye in the chaff, which being consumed by the fire, left cavities in the room of the grains. This might have been intended to modify expansion and contraction, as well as to assist in the gradual distribution of the colouring vapour. The mouth of the furnace and the top of the kiln were no doubt stopped: thus we find every part of the kiln, from the inside wall to the mouth on the outside, and every part of the clay wrappers of the domes penetrated with the colouring exhalation.” [Illustration: Figs. 97, 98, 99.--Castor Ware.]