Oldest trick in the book
QUESTION What is the oldest known magic trick?
DECAPITATION tricks involving doves or chickens were popular in the 16th century, but date to Ancient Egypt.
Djedi is a fictional magician in the Westcar Papyrus, which dates to between 1782 and 1570 BC. He slices off the head of a goose then makes it whole again.
The cup-and-ball routine is a classic fairground attraction. The balls appear to pass through the solid bottoms of the cups, jump from cup to cup or disappear from the cup and appear elsewhere.
Sometimes balls vanish and are replaced with fruit, sweets or even small animals.
A mural in Baqet III’s tomb dating from the 21st century BC shows two men at a table with inverted bowls, which is the earliest known depiction of this trick.
The Acetabularii magicians did cupand-ball tricks in Ancient Rome. They used stones or bone dice and vinegar cups called acetabulum, so the name.
In 65AD, historian Seneca the Younger described his enjoyment of the routine: ‘Such quibbles are just as harmlessly deceptive as the juggler’s cup and dice, in which it is the very trickery that pleases me . . . But show me how the trick is done and I have lost my interest therein.’
From 400 to 1500AD in Europe, magic became linked to witchcraft and went underground. In 1584, English gentleman Reginald Scot published The Discoverie Of Witchcraft (Wherein The Lewde Dealing Of Witches And Witchmongers Is Notablie Detected). By revealing the workings of many tricks, he aimed to stop conjurers being burned at the stake.
However, in 1603, his book was ordered to be burned for encouraging such ‘magical’ practices.
By the 18th century, magic shows were a common fairground entertainment. Showman Isaac Fawkes advertised his act from the 1720s and performed for the aristocracy at private functions.
At his death in 1732, his wealth exceeded £10,000, at least £1 million today.
Iona Mills, Skipton, N. Yorks.
QUESTION How was Neil Armstrong chosen to be the first man to set foot on the Moon?
OFFICIALLY, this was a pragmatic decision: it was easier for Neil Armstrong to exit Eagle, the lunar capsule, first. He was also the senior officer on board.
Unofficially, Nasa felt the reserved Armstrong could better handle the pressures of fame than his extrovert crewmate Edwin ‘Buzz’ Aldrin.
The Apollo 11 crew was announced in January 1969.
Of the 29 astronauts who trained for the Moon mission, Armstrong was chosen as commander with Aldrin as lunar module pilot and Michael Collins as command module pilot.
Immediately, attention turned to who would be the first to walk on the Moon.
The speculation was similar to that which assailed Sir Edmund Hillary and Tenzing Norgay after they had reached the summit of Mount Everest in 1953.
In April 1969, three months before liftoff, it was announced that Armstrong would be the first man on the Moon.
The Eagle’s hatch opened to one side, rather than up or down, giving him a clear path to exit, while pilot Aldrin was pinned in the cramped space of the module.
J. G. Southam, Bolsover, Derbys.
QUESTION Why is tyre pressure in PSI (pounds per square inch) when a tyre is three-dimensional? Surely it should be a cubic measurement.
PRESSURE is a force applied to an area. In this case, the area of the internal surface of the tyre.
If a tyre is inflated to a pressure of 30 psi, then every square inch has a force of 30 lb applied to it.
The volume of the air inside the tyre does not come into it, though to achieve the same pressure, a big tyre with a large internal volume will require more air to be pumped into it than a small one.
This 30 lb per square inch multiplied by the area of tyre in contact with the road surface produces the force that supports the weight of the car.
If the pressure is reduced, more of the tyre comes into contact with the road surface to support the weight of the car.
Increasing the area of tyre in contact with the surface improves traction, particularly on soft surfaces such as sand.
The drivers of wartime amphibious DUKW landing craft could use a low tyre pressure while driving up the beach, then increase it without stopping when they reached a hard surface.
Modern SUVs have to stop to change tyre pressure when moving from soft to hard surfaces.
Driving at high speed with a low tyre pressure will cause excessive flexing of the tyre wall, causing over- heating and damage.
Pounds per cubic inch is a measure of density. The density of air is very small — 800 times less than water.
When a tyre is inflated, the density of the air inside is increased, but it is the pressure that supports the weight of a car, not the density of the air inside the tyre.
Denis Sharp, Littlehampton, W. Sussex.
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