Dew pond

[7] The clay is usually covered with straw to prevent cracking by the sun[7] and a final layer of chalk rubble or broken stone to protect the lining from the hoofs of sheep or cattle.

According to researcher Edward Martin, this may be attained by building the pond in a hollow, where cool air is likely to gather, or by keeping the surrounding grass long to enhance heat radiation.

A Sussex farmer born in 1850 tells how he and his forefathers made dew ponds: The requisite hole having been excavated, the chalk was laid down layer by layer, while a team of oxen harnessed to a heavy broad-wheeled cart was drawn round and round the cup shaped hole to grind the chalk to powder.

A preferred method was to arrange to finish the excavation in winter, so that any fallen snow could be collected and heaped into the centre of the pond to await melting.

It was widely believed that the technique for building dew ponds has been understood from the earliest times, as Kipling tells us in Puck of Pook's Hill: "…the Flint Men made the Dewpond under Chanctonbury Ring.

Landscape archaeology too seemed to demonstrate that they were used by the inhabitants of the nearby hill fort (probably from an earlier date than that of the surviving late Bronze Age structure) for watering cattle.

[13][14] A more prosaic assessment from Maud Cunnington, an archaeologist from Wiltshire, while not ruling out a prehistoric origin, describes such positive interpretations of the available evidence as no more than “flights of fancy”.

[3] The suggestion has also been made that the nursery rhyme about Jack and Jill may refer to collecting water from a dew pond at the top of a hill, rather than from a well.

[13] In turn these conclusions were disproved in the 1930s, when it was pointed out that the heat-retaining quality of water (its thermal capacity) was many times greater than that of earth, and therefore the air above a pond in summer would be the last place to attract condensation.