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To promote a
wider interest in the science of geology through organised lectures,
field excursions and social activities.
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By Ian Donaldson |
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The three information boards by the pools in the Abbots Leigh woods all mention a curious stone, Pulhamite, used in the construction of the dam. This is a Victorian invention - a kind of
concrete made with local stone, and cleverly sculpted to make it look
natural. Famously it was used in the gardens of Buckingham Palace, and
this publicity must have made the inventors rich. Four generations of
the Pulham family specialised in creating natural looking rock gardens,
and other local examples are in Bracken Hill, and Rayne Thatch. Bracken
Hill, the former Bristol University Botanical Garden, at the west side
of the Clifton Suspension Bridge has several deep natural looking rock
pools, romantic arches and small ravines all made of boulders.
Pulhamite also graces the sea fronts of Margate, Folkestone, Blackpool and Lytham St Anne's, and their rock gardens at Sandringham, and Wisley are famous. The mortar used was their own type of Portland Cement, which looked more natural than the brown cements in common use up until their invention. However, Pulhamite was not the only artificial stone made by our forefathers. Wikipedia mentions Mrs Coade's invention of a durable artificial stone used a lot in Georgian architectural features. She called it Lithodipyra, referring to the refiring of
a mixture of crushed pottery "grog" with fine sand, glass powder,
crushed flint, and ball clay. This could be easily moulded into
keystones and window decorations before being kilned at high temperature
for four or more days. Because this is a vitrified ceramic, or
stoneware, Coade Stone has weathered well. A good example is John
Bacon's statue of Father Thames in the garden of Ham House, in west
London.
Another anthropic rock is Victorian Stone, which is a mixture of finely crushed hornblende granite and Portland cement. After moulding, the hardened cast was soaked in a solution of waterglass or sodium silicate, for two weeks, to harden it further. This artificial stone became very popular for it is resistant to weathering and the corrosive atmospheres of sea air and industrial towns. The stone came from the largest granite quarry in Europe, at Mountsorrel in Leicestershire. In the early 1800s several pottery makers managed to produce a fine white unglazed porcelain which they named Parian Ware from its resemblance to marble found on the island of Paros. It is also known as Carrarra biscuit ware. A large statue made of this "artificial marble" can be seen at Bowood House. It is still produced in Belleek, Co Fermanagh. Mass produced statuettes resembling marble are nowadays made from marble dust mixed with a polymer before being compressed in moulds at fairly high pressure.
Sources :- Wikipedia The Pulham Legacy - pulham.org.uk Muspratt's Chemistry, 1855, under "pottery" Dr Ron McEwen - Personal communication
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These look so much like
weathered limestone that I often wondered where they had come from, and
was thankful that no one would allow such vandalism to limestone
pavements nowadays. It was many years before I realised they were in
fact man-made. Rayne Thatch, opposite Bracken Hill is a private house
and garden. A little further afield are the magnificent underground
grottoes and hidden gardens at Dewstow House, Caerwent, near Newport,
Monmouthshire. They are all made of Pulhamite and were only rediscovered
recently at Dewstow Golf Club. 
Various
colours were made, from light grey to beige. Her house in Lyme Regis has
a facade decorated with Coade stoneware and a decorative pavement
outside the nearby Philpot Museum incorporates Coade ammonites in a
strong base. A few years after her death in 1821 the firm went bankrupt,
largely due to the cheaper Portland cement becoming more widely
available. 