The Dangerous Book for Boys. Conn Iggulden
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Название: The Dangerous Book for Boys
Автор: Conn Iggulden
Издательство: HarperCollins
Жанр: Справочная литература: прочее
isbn: 9780007444403
isbn:
2. THE FIGURE OF EIGHT
This is a “stopper’ – it goes at the end of a rope and prevents the rope passing through a hole. A double figure of eight is sometimes used to give the rope end weight for throwing. It’s called a figure of eight because it looks like the number eight.
3. THE BOWLINE (PRONOUNCED BOW-LIN)
This is a fantastically useful, solid knot. It is used whenever a loop on the end of a rope is needed – for a post, a ring, or anything else really.
1 Make a loop towards yourself, leaving enough free at the end to go around your post, tree or similar object
2 Now – imagine the loop is a rabbit hole and the tip is the rabbit. The other end of the rope is the tree. Feed the tip up through the hole – the rabbit coming up.
3 Pass the rabbit round the back of the tree.
4 Pass the rabbit back down the hole – back into the original loop.
5 Pull tight carefully.
NOTE: You can make a simple lasso by making a bowline and passing the other end of the rope through the loop. The bowline does not slip, so is useful for making a loop to lower someone, or to throw to a drowning person.
4. SHEET BEND
This is a useful knot for joining two ropes together. Reef knots fail completely when joining ropes of different diameters – but a sheet bend works very well.
5. A CLOVE HITCH – FOR HITCHING TWO THINGS TOGETHER VERY QUICKLY
This is a short-term knot – the sort of thing you see used by cowboys in westerns to hitch their horses. Its main benefit is that it’s very fast to make. Basically, it’s wrapping a rope around a post and tucking an end into a loop. Practise this one over and over until you can do it quickly.
These five knots will be useful in a huge variety of situations, from building a treehouse to camping, to sailing, to tying up your horse outside a saloon. They will not come easily. They take practice and patience. Knowing this will not impress girls, but it could save your life – or your horse.
Questions About the World – Part One:
1 Why is a summer day longer than a winter day?
2 Why is it hotter at the Equator?
3 What is a vacuum?
4 What is latitude and longitude?
5 How do you tell the age of a tree?
1. WHY IS A SUMMER DAY LONGER THAN A WINTER DAY?
In Australia, the shortest day is 21 June, and the longest falls on 21 December. In the northern hemisphere, 21 June is midsummer and midwinter falls on 21 December. Christmas in Australia is a time for barbecues on the beach.
Although the North Pole points approximately at the star Polaris, the Earth’s axis is tilted twenty-three and a half degrees in respect to the path it takes around our sun.
While the northern hemisphere leans towards the sun, more direct sunlight reaches us. We call this period summer. 21 June is the day when the North Pole points directly towards the sun, and the tilt is at maximum. The days are longest then as most of the northern hemisphere is exposed. Down in the south, the days are shortest as the Earth itself blocks light from reaching the shivering inhabitants.
As the Earth moves around the sun, the tilt remains the same. The autumnal equinox (22 or 23 Sept) is the day when day and night are of equal length – twelve hours each, just as they are on the vernal equinox in spring on 20 March. ‘Equinox’ comes from the Latin for ‘equal’ and ‘night’.
When the northern hemisphere leans away from the sun, less light reaches the surface. This is autumn for us, and eventually winter. Longer days come to the southern hemisphere as shorter days come to the north. The summer solstice of 21 June is also the moment when the sun is highest in the sky.
The Earth is actually closer to the sun in January rather than June. It’s not the distance – it’s the tilt.
The best way to demonstrate this is by holding one hand up as a fist and the other as a flat palm representing the Earth’s tilt. As your palm moves around the fist, you should see how the tilt creates the seasons and why they are reversed in the southern hemisphere. Be thankful that we have them. One long summer or one long winter would not support life.
At the midsummer and midwinter solstices, the conditions can become very peculiar indeed. The summer sun will not set for six months at the North and South Poles, but when it does set, it does not rise for another six. Northern countries such as Finland also experience the ‘midnight sun’ effect.
2. WHY IS IT HOTTER AT THE EQUATOR?
There are two reasons why the Equator is hotter than the rest of the planet. Strangely enough,the fact that it is physically closer to the sun than, say, the North Pole is not relevant. The main reason is that the Earth curves less in the equatorial region. The same amount of sunlight is spread over a smaller area. This can be clearly seen in the diagram below.
Also, the sun’s rays have to pass through less atmosphere to reach the equatorial band – and so retain more of their heat.
A perfect vacuum is a space with absolutely nothing in it – no air, no matter of any kind. Like the temperature of absolute zero (–273.15 °C /0 Kelvin), it exists only in theory. The light bulbs in your home have a ‘partial vacuum’, with most of the air taken out as part of the manufacturing process. Without that partial vacuum, the filament would burn far faster, as СКАЧАТЬ