Talk: Tuesday 17th September 2013.
‘Excavation of a Medieval Sugar Mill in Cyprus’. By Mr Gerald Hennings, RCEA.
The illustrated talk followed the AGM. The theme was “Industrial Archaeology”.
The talk began with a brief history of sugar production. Sugar cane had been known in the Pacific Islands for two millennia. The cane was chewed as a sweet and this use worked its way slowly towards the Levant. On the way, a method of making sugar by a crude manual process originated in India around 600BC. By 700AD, small quantities of sugar were being made in Syria – where it came to the notice of the Venetians who began importing it to Venice for sale in Southern Europe in the 8th C AD. They had lands in Cyprus and introduced the cultivation of sugar cane there around 10th C. When the Crusaders captured the Holy Lands, they refined and mechanized the sugar-making process, going in to large scale production.
At this time, the only source of sweetness in England was honey – unless you were rich enough to be able to buy sugar from Venice. Sugar beet was known, but was only used as a cattle fodder. The process of making sugar from beet was not discovered until 1784 and not used commercially until the 19th C.
When the Knights were expelled from the Holy Lands in 1293, they moved first to Cyprus (where they had estates, and introduced large scale sugar production there. By 16th C, Cyprus was the third largest producer of sugar in the world. The introduction of slave labour and better growing conditions in the West Indies rendered Cyprus sugar uncompetatively priced; production in Cyprus ceased around 1610.
Gerald went on to describe how the mills became derelict, robbed of machinery, buildings demolished – the sites buried and completely forgotten/built over. Archaeologists had found some of the mills in the course of their excavations, but did not know what they were.
He went on to describe the sugar making process. Cane propagation, cutting, crushing to extract the juice, boiling/ refining, crystalisation and sale. He described the layout and showed that the only drawing we had from medieval times was not what excavation revealed. Since only the stonework (most of it below ground) existed, engineering insight was needed to interpret the plant. Photos of what had been found were shown and the interpretation explained The power to drive the cane crushing mill was derived from a “Greek wheel” which was a horizontal water wheel, fed by an aqueduct and chute in an underground chamber. The wooden wheel was shown to be 5 metres in diameter and the drive taken up through the roof to rotate one or two (?) crushing stone rollers in a stone tub above. A roller was replaced in the tub, using a REME recovery vehicle. The stone weighed 11⁄4tons.
Interpretation of the chute and driving arrangement for the roller(s) had to be interpreted from the remaining stonework. All the stone bearings were replaceable without having to dismantle the mill. The wheel itself must have been assembled in situ – there was no way of getting into the chamber otherwise.
After the juice was extracted from the cane, the crushed cane was dried in the sun and used to fuel the furnaces for the next stage – boiling off the water and refining. The crushed, dried cane (bagasse) created very fine ash on burning, which had to be kept clear of the sugar. The furnaces were in a trench on the downwind side of the site and the boiling hearths were inside a building with no windows on the stokehole side. The hearths were limestone slabs, preventing any ash coming into the building. Temperature had to be tightly controlled to prevent burning the sugar; each boiling took 6 hours of continual stirring and skimming. This was repeated three to five times for quality, Boiling was in large copper vats (none found, of course), but experimental archaeology shows that the copper ( a major product of Cyprus) has a catalytic effect which allows more water to boil off than if other materials are used.
After boiling, the syrup was poured into pottery cones (made on site – a kiln was found at the Kouklia mill) and allowed to crystallise – taking 8 days. The sugar loaf was extracted and sent for sale or ground and exported as a powder. 3,000 pots were required on each site and 400 people worked at each mill for three months in the year.
After a tea break, Gerald explained how two of the three mills excavated were up-rated by replacing the water wheel with a crude, horizontal turbine system. Power output (estimated at 4 to 7 horsepower) was not increased; the crushing mill itself not being modified, but a smaller diameter wheel could be used – 4metres (large pieces of good timber were hard to come by in Cyprus). This system was less affected by fluctuations in the water supply in the aqueduct. The Royal mill at Kouklia Stavros and the mill run by the Knights of St John at Kolossi Castle had been modified; the Venetian-owned one at Episkopi Serayia had not.
Gerald related how they had found a donkey powered mill alongside the water-powered one at both Episkopi and Kouklia which suggested a standby facility for times when water levels or maintenance prevented use of waterpower. This was a late addition – not shown on the 16th C plan retrieved from the library in Venice.
The talk concluded with a review of activities engineers might like to be involved with in archaeology
Talk: Tuesday 17th September 2013.