We know very little about the early history of Africa. There must have been great
civilizations there, but very few of them developed writing or left any records. Some
civilization built fine communities, such as the east coast port of Kilwa or the mysterious
stone complex of Great Zimbabwe. After about AD 700, Muslims from the Near East
began to take over many coastal regions and trade routes. One of the wealthiest of
the medieval African empires was Mali. Starting in 1240, its Islamic rulers built up a
kingdom stretching for around 1,600 km over West Africa. Much of the land was desert,
but Mali grew rich from gold.

The bubonic plague (or ‘Black Death’) was a disease which brought death to most parts
of Asia, North Africa and Europe. The first outbreak was recorded in 1331 in China. The
plague started as a bloody swelling in the armpit or groin and quickly invaded the whole
body. It was highly contagious and killed millions of people. The infection probably
began on the steppes, the grassy plains of Asia. IT was carried by fleas which lived in
the fur of the rat. The rats lived closed to humans and thus the disease spread rapidly.
Corpses were left out in the road for people to collect, thus causing the disease to spread
even further.

 The youngest son of Henry II, John, inherited from his brother Richard the throne of
England, as well as the Plantagenet dominions of France, which he had lost to the French
by 1204. John’s failure to recapture these territories, his dispute with Rome over the
Pope’s choice of a new Archbishop of Canterbury, and a high level of taxation, had the
English nobility up in arms against him. In 1215 they forced the King to agree to the
Magna Carta, guaranteeing their rights in relation to those of the crown. It was intended
to protect the rights of nobles, and made sure that no-one was imprisoned without a fair
trial. Copies of this document, which tried to put an end to the king’s abuse of his power,
were distributed across the whole of England. This led to civil war, which only ended
with John’s death in 1216, Despite all these disasters, it is now known that John was
much better king than history has actually portrayed him.

The Byzantine emperor, a Christian monarch who lived in Constantinople, needed help.
He turned to the pope, who in 1095 called for all Christians to start a holy war against the
Suljuk Turks. Thousands rushed to join the Crusader armies. They crossed into Palentine
and recaptured the important cities of Nicaea and Antioch. Jerusalem fell in 1099 after a
desperate siege lasting six weeks, and the Crusaders took terrible revenge by slaughtering
thousands of Muslims. There were to be three more crusades: one in 1144, the second
in 1187 and finally the Children’s Crusade in 1212. Fifty thousand children set off from
France and Germany for the Holy Land. Many died on the journey, many more were
captured and sold as slaves in Africa.

Traditionally, glue is made from boiling up the bones, skins and other parts of animals such as fish
or horses in order to extract the gelatin, which is then purified and concentrated to make a sticky
substance that will form a bond as it dries. There are now many different types of glues, made from
plant material or minerals such as petrol, as well as different kinds of synthetic glues. One of the
simplest glues is flour-and-water paste and traditional wallpaper paste is made with starch. Latex
adhesives were originally made from the latex extracted from rubber trees, but synthetic forms are
now also available. Another type of synthetic glue is epoxy resin, in which the user mixes an adhesive
substance with equal quantities of a hardener. The two substances react chemically together, causing
the adhesive to set rapidly. Glues are widely used in many industries, such as furniture-making and food-
packaging.

There are a few factors that govern how valuable a stamp is to stamp collectors: the most important
is how rare it is. Obviously, very old stamps are uncommon so these, such as the ‘Penney Black’ very
seldom come up for sale and so are unbelievably expensive. Other things that might make a stamp rare
might be where a mistake was made in the printing and the stamp was withdrawn after only a few had
been sold. Undamaged stamps are more valuable than similar ones that have been damaged.

A cloud is made up mainly of water. When hot air rises from the land or the sea, it carries water vapour
with it. Because the atmosphere usually gets colder with height, and cold air can hold less vapour
than warm air, the vapor eventually condenses in the form of water droplets or ice crystals around
particles of dust to form a cloud. If it continues to cool further, the cloud will become denser until the
atmosphere is no longer able to hold the moisture and rain, hail or snow will fall. The general rule is that
the deeper a cloud is relative to the deeper a cloud is relative to the height of its base above the sea or
ground, the more heavily it will rain, hail or snow, so thin, high clouds produce no rain, while thunder
storms produce a great deal.

It would be easy to think that a duck’s feathers would soon become waterlogged so that it would sink,
but in fact, ducks, geese and swans, as well as seabirds, have waterproof feathers, which enable them
to swim and dive beneath the surface of the water. Ducks create this waterproofing using the oil from
the preen gland, near the base of the tail, which they spread through their feathers and the underlying
dense layer of down with their bills. A layer of fat under their breast skin also helps to keep them
buoyant. Different ducks feed in different ways, some dive, some upend and feed from the bottom of
the lake or river while others ‘dabbles’, stirring up the water with their feet to find food.

Dinosaurs lived for an enormously long time-some 150 million years – before they died out about
64 million years ago. All the dinosaurs disappeared at about the same time. However, whether
this happened over a few days, a few years, one or two centuries, or even a few thousand years is
impossible to say. Many people believe that the dinosaurs became extinct as a result of climate change
after a huge meteor or a small asteroid struck the Earth. The extinction of the dinosaurs was not an
isolated event. At the same time most marine reptiles and pterosaurs also died out.

Several families of birds can be trained to ‘talk’, but in reality they are simply mimicking noises without
really understanding what they are saying, although they can be taught to associate a given word or
phrase with a given action, for example saying ‘give us a peanut’ to get a reward. The best talkers are
parrots and mynas, and members of the crow family such as crows, jackdaws and ravens can also learn a
few simple words. They can do this because the are highly intelligent birds and they are excellent mimics
in the wild. Other bird mimics that do not pick up speech are starlings and some of the bowerbirds in
Australia, including on individual that had learned to copy the noise of the logging machines that were
destroying his habitat.