Naval Signalling Codes  Systems of communication such as radio, semaphore and morse have, to a great extent, outdated naval signalling flags. However, this system of signalling, the same one Nelson used during the Battle of Trafalgar is still used today, especially when electronically-operated systems fail; and it is still very much a matter of course for all naval personnel to be familiar with the code. The International Code of Signals used...

Which famous people have written books in cipher? Many famous people have tried to keep their work secret by means of ciphers. One of them was Leonardo da Vinci, whose notebooks contained details in cipher of his revolutionary ideas. Writing and drawing about such advanced mechanics as flying machines and armoured fighting vehicles in the fifteenth century, Leonardo’s sanity could well have been questioned- he may even have been accused of...

Can cats really see in the dark? No animal can see in complete darkness, but cats are much better than most animals at seeing in very dim light. Many cats do their hunting on moonlit nights, and animals that come out at night — nocturnal animals — have a special layer in the back of their eyes called a tapetum which multiplies the amount of light entering the eyes. This makes...

Which is the fastest Cat? Most of the big cats can move quickly when they have to, for the ability to catch fast-moving prey is necessary if they are to find food. A lame wild cat soon dies from hunger because it cannot catch its prey. The fastest cat, and indeed the fastest animal on four legs, is the cheetah. Lightly built with a muscular body and long legs, the cheetah...

Which is the largest Cat? Lions and tigers are the biggest of the cats, but because there is little to choose between them, it is difficult to say which is the largest. Hunters sometimes used to stretch the skins of lions and tigers they had shot, and this of course gave a rather false impression of the size of the animal when it was alive. 130th lions and tigers often grow...

How do big cats catch their prey? All the animals shown on this page are  members of the cat family. The big cats are well known for the way in which they hunt mid kill other animals to eat as food, although many of them will scavenge and eat dead animals, or carrion, when live prey is scarce. To be able to hunt other animals, cats have strong senses in order...

What is Motion? How astronomers came to understand the structure of the solar system. They arrived at their conclusions by observing the planets and measuring their distances from the Earth and the speed of their orbits. Their findings were not completely accurate because these astronomers did not understand the laws of motion. In fact, these were not fully under-stood until this century, when Einstein, continuing the work of Isaac Newton, formulated...

Why is Johann Kepler so important? Tycho Brahe first heard of Kepler when he read his book Mystery of the Universe, published in 1596. This supported Copernicus’s theory that the Sun was the centre of the Universe and tried to show how the distances of the planets could be worked out. Brahe was so impressed that he employed him to study the movements the planet Mars and so prove Brahe’s theory...