“The most preferable clay of any is that of Amblecote, of a dark blewish colour, whereof they make the best pots for the glasshouses of any in England; nay, so very good is it for this purpose that it is sold in the place for 7_d._ the bushel, whereof Mr. Gray (an ancestor of the present Earl of Stamford and Warrington) has 6_d._ and the workman 1_d._, and so very necessary to be had that it is sent as far as London, some time by waggon and some time on pack horses to Bewdley, and so down the Severn to Bristol, and thence to London.” “The goodness of which clay and cheapness of coal hereabouts no doubt has drawn the glasshouses both for vessels and broad glass into these parts, there being divers set up in different forms here at Amblecote, Oldwynford, Hollowaysend, and Coburnbrook.” Stourbridge clay (_properly so called_) is found only in a comparatively small district, say within a circle of not more than two miles, taking the valley of the Stour at the Lye as the centre, and at depths varying from three or four yards from the surface to one hundred and eighty yards; its position in the strata is in all cases below the thick coal, at distances varying from twelve to twenty-five yards; and it is generally overlaid by a shaly, friable kind of coal, called “batts,” from twelve to twenty-four inches thick. The thickness of the seam varies very much, rarely exceeding thirty-six to forty-two inches, and sometimes thinning down to five or six inches when close to faults or small disturbances in the measures. The quality is very variable, in some instances as hard as stone, having to be blasted with powder, and in others soft and easily workable. There is a great variation in its component parts, arising principally in the proportion of silica; a clay containing only about fifty per cent. of silica being very inferior, and contracting very much on exposure to intense heat. In order to show this difference in a practical form I have had eight clays from as many mines in the Stourbridge district, prepared under precisely similar circumstances, subjected to the same heat, and all burnt in the kiln at one time. The result showing the great variation and power of resisting heat, since, in the eight samples, hardly two are of the same weight and size. The eight bricks all made in one mould. No. 1. No. 2. 4-10/16 × 2-13/16 × 1. 4-11/16 × 2¾ × 1. 15 oz. 1 gr. 16 oz. No. 3. No. 4. 4¾ × 2-15/16 × 15/16. 4¼ × 2-10/16 × 14/16. 16 oz. 1 gr. 15 oz. 1 gr. No. 5. No. 6. 4-11/16 × 2-13/16 × 1-1/16. 4-6/16 × 2¾ × 14/16. 17 oz. 2 gr. 15 oz. 1 gr. No. 7. No. 8. 4-9/16 × 2¾ × 13/16. 4-9/16 × 2¾ × 1. 13 oz. 2 gr. 15 oz. 2 gr.