This stone is procured from the Portland and Purbeck series of the oolitic formation as developed near Tisbury, Wardour Castle, in Wiltshire.

It is known also as Wardour stone, and in London as Tisbury stone.

The siliciferous nature of the cement which binds the particles (carbonate of lime) of the stone gives it excellent weathering qualities, while the softness and even grain of some of the beds renders them capable of being elaborately worked.

There are four distinct varieties of the stone.

1 Professional Papers, Royal Engineers, vol xii

The Trough or Hard Bed is of a close even texture, of yellowish-brown colour.

It has an average thickness of 2 feet 6 inches, but stones may be obtained 3 feet 6 inches thick and of any reasonable length and breadth - the random blocks averaging 16 cubic feet.

It is used principally for steps, also for cornices, copings, sills, plinths, chimney-pieces, paving, road metal, heavy engineering works, and in any position exposed to wet and hard wear.

The Scott or Brown Bed is of warmer colour than the hard bed. Average thickness of bed 3 feet, maximum 4 feet, random blocks average 16 cubic feet.

Principally used for ashlar mouldings, carvings, random rubble, and for building purposes generally.

The General Bed, from the Garden quarry, is of a rich yellow tint and fine texture. It is capable of being elaborately carved, and is chiefly used for that purpose, also for ashlar, mouldings, etc.

The average thickness of bed is 4 feet, maximum 5 feet.

Strength

Resistance to crushing per foot sup.

Tensile strength per square inch.

Hard bed ....

196 tons.

500 lbs.

Scott bed ....

104 „

206 „

General bed...

100 „

355 „

Chemical Analysis

Silica...

10.4

Carbonate of lime...

79.0

„ magnesia.

37

Iron alumina...

2.0

Water and loss....

4.2

Working

The stone has to be cut with a wet saw, and the relative cost of working the beds compared with Portland is stated by the proprietors to be-

Portland and Hard bed ....

1.0

Scott and Garden bed...

0.6

Buildings in which used. - Salisbury Cathedral, Tisbury Church, Wardour Castle, Fonthill Abbey, Priory Church, Christ Church; Post Office, Westminster Eoad, London; Post Office, Exeter; Sorting Post Office, Hampstead; London and County Banks, Hastings and Banbury; restoration of Chichester and Rochester Cathedrals, and of Chapter House, Westminster Abbey; Longford Castle, Wilts; Crewe Hall, near Chester, etc. etc.

Kentish Rag1 is found in the Greensand formation, in a district running through the central part of Kent, about thirty miles long and from four to ten miles broad, including the towns of Sevenoaks, Maidstone, Lenhara, etc.

Beds

The Ragstone is found in beds varying from 6 inches to 3 feet in thickness, alternating with fine sand known as Hassock, which is frequently so consolidated as to form a stone that can be used for building.

1 Taken chiefly from Observations on Kentish Ragstone, by J. Whichcord.

The hassock is generally found adhering to the ragstone, and at the bed of junction organic remains often occur.

The ragstone itself is a very compact, heavy stone, which absorbs very little water, and resists the weather well.

The hassock, attached to it, is a calcareous sandstone, soft, porous, and very perishable under atmospheric influences.

There are several beds in a Kentish ragstone quarry; many of them are worthless. It may be interesting to mention a few of the most useful.

After a top layer of mould and loam there are two or three beds of hassock and ferruginous sand, after which come the more useful beds, the best of which are mentioned below in succession.