DORSETSHIRE. This county yields many mineral substances useful in the arts. The eastern parts of the county are mostly occu pied by the plastic clay. Potters' clay in beds of various thickness and at different depths alternates with loose sand in this formation in the Trough of Poole; it is sent to Stafford shire, where it is mixed with ground flints, and employed in the finer kinds of pottery. Beneath the potters' clay lies a seam of very friable earthy brown coal, somewhat like coal. The Purbeck strata, belonging to the upper series of the oolitic formation, consist of argillaceous limestone alternating with schistose marl; they crop out from under the iron-sand in the Isle of Purbeck. A variety of the Purbeck stone, known as Pnr heck marble, was formerly much used in building. The Portland °elite, another mem ber of the same series, which succeeds tho Purbeck stone, occupies the remainder of the Isle of Purbeck and the whole of that of Portland. It consists of a number of beds of a yellowish white calcareons freestone, generally mixed with a small quantity of siliceous sand. The varieties of this forma tion afford the greater part of the stone used for architectural purposes in London. In the Portland quarries, the saleable stone occupies layers of strata situated several feet beneath the surface ; and the quarrymen have to exert great labour in the removal of the superin cumbent rubbish, before they can reach the stone. The thickness of workable stone
varies from 7 to 10 feet, and the works pro ceed at the rate of about an acre of good stone per annnm. Almost the entire mass of Portland Isle consists of the Purbeck series.
The Dorset butter is in good repute in London and Portsmouth for ship provision as well as domestic use : it is not so salt as the Irish, and is therefore preferred, although the Irish is richer when it is of the best quality. Dorset salt butter, when well washed, is very conunonly sold in London for fresh butter. The butter is made from the cream, and the skimmed milk is made into cheese. The Dorsetshire skim-milk cheese is preferred on account of streaks of blue mould which fre quently run through it.
In 18-17 an act was passed for the forma tion of a harbour of refuge off the Isle of Portland by the construction of a breakwater, extending northward from the north-eastern point of the island for miles, so as to include a large part of Portland Road. Owing to the facilities afforded by the presence of an abundant supply of suitable stone on the island, it is estimated that the cost will not exceed 500,0001. The works are now steadily advancing.
Dorsetshire contains very few towns of a manufacturing character, and will only to a limited extent take part in the Industrial Exhibition.