What a palava!
QUESTION How are the excessively high temperatures in volcanoes measured by scientists?
A thermocouple probe can be inserted into a lava flow and the temperature can be read off a hand-held device.
A thermocouple takes advantage of the thermoelectric effect, also known as the Seebeck effect.
In 1821-3, German physicist thomas Seebeck found that a circuit made from two different metals, with junctions at various temperatures, would deflect a compass magnet. the temperature difference produces an electric potential (voltage), which can drive an electric current in a closed circuit.
A thermocouple can use the Seebeck principle to determine extreme temperatures using the fact that the size of the current is directly related to the difference in temperature between the two junctions.
however, inserting a thermocouple probe into a lava flow for long enough to get a good reading is a perilous business.
World expert George Walker said: ‘the temperature of a lava flow is inversely proportional to the comfort of the volcanologist making the measurement.’
Where temperatures are too extreme for the volcanologist to get near, a thermal Ir imaging camera can be used.
however, it will accurately measure only the surface temperature of the lava. Scientists must then use mathematical modelling to calculate the temperature deeper into the flow.
Dr Ian Smith, Cambridge.
QUESTION Is it true that V1 and V2 flying bombs were not launched against Russian targets in the East during World War II?
V-WeAponS, or Vergeltungswaffen ( which means retaliatory weapons), comprised the V1, a pulse jet-powered cruise missile, and the V2, a liquid-fuelled ballistic missile.
While designed for strategic bombing during World War II, their poor range and accuracy meant they were only deployed in the West as an indiscriminate weapon of terror.
the V1 and V2 had deficiencies that made them unsuitable for firing into the vast wastelands of russia.
each weapon’s limitations in accuracy meant they had a cep (circular error probable) of several miles. they were useless against tactical targets, troop concentrations, railways or roads. they could barely target a town, let alone a bridge, dam or power station.
V1 and V2 attacks on British cities were an attempt to destroy morale and put an end to the war in the West.
In the east, despite there being a couple of V1 test sites in poland, it was quickly realised there weren’t enough population centres in range for such terror attacks. V1s had a range of 150 miles and V2s around 200 miles. V1s were launched from aircraft or, to target Britain, from France and holland.
It would have been impossible to deploy the V2 in the east given the substantial support required to mount operations.
Jonathan Holme, Beccles, Suffolk.
QUESTION How did London’s famous markets get their names?
london has at least 25 historic markets and 50 more working markets.
Borough market claims to have existed since 1014. the name comes from burh, a fortification or fortified settlement developed in Alfred the Great’s time to defend against the Vikings.
Billingsgate market dates from the 14th century. It was described as a ‘free and open market for all sorts of fish whatsoever’ in 1699.
the first market building was constructed on lower thames Street by the builder John Jay in 1850 and expanded in 1873 when it became the world’s largest fish market. It is named after the city ward of Billingsgate, where the market was located before it moved to poplar in 1982.
Billingsgate is thought to be the site of an ancient water gate, a fortified gateway leading to a quay or wharf. the 12th-century cleric and historian Geoffrey of monmouth wrote that it was named after Belinus, a mythical king of pre-roman Britain.
the fruit and vegetable wholesale market at covent Garden was granted a charter by charles II in 1670.
the land was owned by Westminster Abbey during the middle Ages and was referred to as ‘the garden of the Abbot and convent of Westminster’ — covent being a distortion of convent. the market relocated to nine elms in 1974.
Greenwich market dates back to the 14th century. the name comes from the Anglo-Saxon Grenewic, meaning green port or harbour.
leadenhall market also dates back to the 14th century, though the current building is from 1881. In the middle Ages, traders from outside london could sell their wares there. It got its name from a lead-roofed mansion that stood there.
Spitalfields market was established in 1682 specialising in fruit and vegetables. It was called the spitel fyeld in 1561 and belonged to a medieval priory called the new hospital of St mary without Bishopsgate, or St mary Spital.
portobello road market in notting hill began as a food market in the 19th century, but was supplanted by antique dealers after World War II.
the street was named in honour of Admiral edward Vernon’s 1739 victory over the Spanish at porto Bello, now in panama. districts in edinburgh and in dublin also acquired the name of portobello at this time.
the name, which is said to have been coined by christopher columbus, means ‘beautiful port’.
Nigel Armfield, London N14.
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