Science: Technoquest - Weather records/ Cats' eyes/ Blue Whales/ Noses/ Smelly eggs

Questions for this column may be submitted via e-mail to sci.net@campus .bt.com
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Q Who kept the first weather records?

Our Eurocentric view of science and technology sometimes fails to credit the debt we owe early scientists and inventors in the East. The study of oracle bones from the Shang dynasty capital of Anyang shows that systematic meteorological records were being kept as long ago as the 13th century BC. The Anyang oracle bones also refer to rainbows, which were thought to be visible rain dragons. In the Song period, AD 1070, a double rainbow was described as being due to the reflection of sunlight from suspended water droplets. This was two centuries before Qutb al-Din al-Shirazi, a Persian, first satisfactorily explained that, in a rainbow, light is refracted twice and reflected once through a water drop. In Europe, the use of such a simple instrument as the rain gauge only started in AD 1639, but there were rain gauges in Korea two centuries earlier, and in China in the 13th century.

Q Why do cats' eyes glow in the dark?

The back of a cat's eye reflects a small amount of the light that shines on it so that the optic cells get extra stimulation - improving the cat's night vision. This reflected light shines back out of the cat's eye so that it seems to glow in the dark.

Q How big is a blue whale?

A blue whale can be up to 30 metres long and weigh about 143 tonnes - that's about three times the length of a London bus and about 18 times as heavy. Its large size protects it against predators, scaring other animals away: it is the largest animal on Earth. An animal this large could not survive on land because its own weight would squash it. In the sea, it has water to support it against the effects of gravity.

Q What is the evolutionary advantage to Homo sapiens in having a prominent nose, as most other primates have flat noses? (asked by Luela Palmer)

The nose serves two main purposes: to moisten the air we breathe, and to warm it. Races from Equatorial regions tend to have flatter noses, as they don't need to put extra moisture into the air they breathe, whereas people who live in desert countries tend to have longer noses as the air is very dry, and needs more moisture added. On the other hand races from colder countries, such as the Inuit and Tibetans, have flatter noses because the importance of warming the air you breathe is outweighed by that of not losing heat through your extremities. It's difficult to establish an exact evolutionary advantage, as selective pressures vary between different people living in different environments, but the overall advantage compared with primates is that Homo sapiens roamed to practically every environment in the world - and adapted through selective pressures to survive in each particular environment.

Q Why do bad eggs float?

As soon as an egg is laid it starts to lose moisture through its shell. This moisture is replaced by air, which makes the air sac in the egg larger, and the egg less dense. At the same time, proteins in the egg white break up, producing hydrogen sulphide - which smells horrible. This gas eventually makes the egg light enough to float.

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