Point of Interest
1. ARE MARINE VOLUNTEERS AT RISK OF BEING SUED?
(Summarized extract from National Conference of Australian Plaintiff Lawyers’ Association, 2000)
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Based on over-generalised reference to US litigiousness, there is a grossly exaggerated urban myth that rescuers are constantly at risk of being sued. Rescuers and Good Samaritans are generally encouraged and supported by the courts. Taking into account the urgency of the situation and the desirable philosophy of protecting others from harm, leniency is shown if they unwittingly do damage.
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Most of the Australian emergency services legislation is concerned with granting “powers”, rather than imposing duties.
2. WHICH WAY DOWN THE PLUG HOLE?
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Earth spins anti-clockwise when viewed from the North Pole, and clockwise when viewed from the South Pole. You can see this difference by observing a spinning ball from the top and bottom. This is known as the Coriolis effect, and is the reason for cyclones spinning anticlockwise in the northern hemisphere and clockwise in the southern hemisphere. The Coriolis effect is zero at the Equator and maximum at the Poles, and it works only over large distances, increasing as a moving object goes faster.
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The Coriolis effect has little or no influence over the spin of water draining out of a bathtub. Factors influencing the direction of its spin are mainly the shape of the bath and the waves and currents generated by filling of the bath and by the hand pulling out the plug. In order to see the Coriolis effect in the bathtub, you will have to carry out a controlled experiment. The tub must be circular, and all artificial forces must be allowed to die down by letting the water sit for many days. Such a successful experiment was reported in a 1965 edition of Nature, re-reported in Helix in the mid-90s.
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The influence of the Coriolis effect is also not guaranteed in the case of storms smaller than cyclones. Dust devils can spin either way and tornadoes have been known to spin the “wrong” way.
3. SPLITTING AND WANDERING MAGNETIC POLES
(Professor Pat Quilty, Head of Antarctic Division’s Research Program, quoted in the Sydney Morning Herald in 1996)
On Magnetic Poles, the magnetic lines of force run at right angles to the earth’s surface. These poles not only wander but also sometimes split. In the Northern Hemisphere there are now two magnetic poles: one in Canada and the other in Siberia. The South Magnetic Pole, which is about 1500 nautical miles from the Geographical Pole and located in southern South America, is in the process of splitting into two. It has also probably shifted some 2000 miles in 400 years, which is an immense rate of movement. The nickel-iron core of the earth is surrounded by a fluid and then by a silicate mantle strewn with bits of iron. The movement of these bits of iron in the internal convection currents is the explanation given for the wandering and splitting of the magnetic poles.
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(Author’s Note: Another theory is that the North Magnetic Pole is moving southwards, and the South Magnetic Pole is moving northwards on the opposite sides of the earth. In a few thousand years, the two poles may come to be located over the equator and then eventually swap their current locations.)
4. FINDING DIRECTION BY THE MOON
(J.P. Jewell, Australian Volunteer Coast Guard Association)
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