My Science School

                 Mammals and birds are the main groups of warm-blooded animals. Some very active fish, such as tuna, are also warm-blooded. However, the mechanism that heats their bodies is different from that of mammals and  birds.

What is the advantage of being warm-blooded?

                    The chemical reactions that power the bodies of animals work best at warmer temperatures.

                   Warm-blooded animals are able to live and move about at any temperature that they experience in their normal environment. They can do this because their internal temperature is always the same. Cold-blooded animals, however, become sluggish as the temperature around them drops, and many will hibernate or migrate in very cold weather.

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                     Vertebrates have a backbone that provides support for the muscles and protection for the spinal cord. The backbone is actually a series of small bones called vertebrae. They are jointed together and locked with rope-like ligaments to provide a flexible but extremely strong anchor for the back muscles. The spinal cord runs down a channel inside the vertebrae, providing protection from damage. In some primitive fish, such as sharks and rays, the spine is made of a tough rubbery material called cartilage.

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                 The animal kingdom is divided into two groups — vertebrates and invertebrates. The vertebrate group contains all animals with backbones (as well as some that have a primitive form of backbone).Vertebrates include fish, amphibians, reptiles, birds and mammals. Invertebrates have no backbone. They include worms, molluscs, corals, scorpions, spiders, insects and crustaceans such as crabs and lobsters. Scientists divide these two main groups into smaller groupings that show the relationship between all these animals.

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                 Animals are one of the major groups of living things. The other two groups are plants and fungi.

                The cells of animals differ from plant cells because there is no hard cell wall. The cell contents are held together with a flexible membrane. Animals are not able to make their own food, but must obtain food from plants or fungi. Most animals are able to move about and to respond to changes in their environment.

About three-quarters of all living things are animals.

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            Various types of mechanical calculators had already been invented when, in 1835, Charles Babbage, a professor of mathematics at Cambridge University, described the principle of an analytical engine. This was the world’s first programmable computer, using a system of cogwheels and data entered by means of punched cards. Ada, Countess Lovelace was also a mathematician, and she wrote several computer programs for Babbage’s device. The analytical engine was, sadly, far ahead of its time and was never developed past its first crude form.

            The first practical computer was Colossus, a huge mechanical device invented to help break German secret codes during World War II. It was based on the theories of the eccentric mathematician Alan Turing.

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            In 1771, Nicolas Cugnot produced what was probably the first self-powered vehicle, driven by steam. In 1801, the Englishman Richard Trevithick ran a steam car along a road in Cornwall, reaching a speed of 14 km/h. From then until the end of the 1800s, all successful road vehicles were powered by steam, although there were many experiments with petrol engines. Then in 1885 Karl Benz in Germany built the first successful modern motor car, powered by a petrol engine.

 

 

           Frank Whittle designed the first true jet engine between 1928 and 1930, but it was not used to fly a jet aircraft until 1941. Meanwhile, the German engineer Hans von Ohain began work on a similar jet engine in 1936. His engine had flown a Heinkel aircraft by 1939. German developments proceeded more rapidly, and Germany had a jet fighter plane in action before the end of World War it.

 

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            In 1903, at Kitty Hawk in the United States, Orville Wright made what is said to be the first controlled powered flight of a heavier-than-air craft. People had already flown small airships, but there was now a race to make the first successful aeroplane. The Wright brothers and other would-be pilots had already built several gliders. The Wright biplane looked like a huge box kite, with a home-made engine that drove two propellers by means of chains – but it flew and it was controllable.

            Clement Adler, in France, had flown under power in 1890 in a bat-shaped aeroplane powered by a steam engine. However, the aircraft was not controllable; so many people do not accept his attempt as the first flight.

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            Alexander Graham Bell (1847-1922) was born in Scotland but moved to the USA. He realized that sound consists of vibrations, and he began working out a way of changing these vibrations into electrical impulses. These impulses could then be carried along a wire – this was the origin of the telephone. His rival, Thomas Edison, soon produced a much improved version of Bell’s telephone. Bell retaliated by devising a better version of Edison’s own phonograph.

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                        Although he was actually a draper, the Dutchman Antonie van Leeuwenhoek (1632-1723) ground glass lenses and used them to examine the world about him. In the 1670s he made his first crude microscope with a tiny lens, and this allowed him to be the first person to see microscopic life such as bacteria, yeast and living blood cells. During his career, van Leeuwenhoek ground a total of 419 lenses, and his microscopes became progressively more effective.