GREAT INVENTIONS (ENERGY AND ENGINES)

It is hard to believe that until 300 years ago, jobs could only be carried out by people, animals, or by the energy of wind and water. This changed in the eighteenth century, when the steam engine was invented, which boosted transport and manufacturing machines. The Steam Era continued for 200 years, until electric motors and liquid fuels arrived.

The first steam engines were used to extract the water from the mines. In 1763 they asked a Scottish engineer named James Watt to fix one of these engines, but he saw a way to improve it and in 1769 he invented a more efficient steam engine. Watt's invention was so successful that it was used to move the machines of the factories. His invention also helped other people develop steam locomotives for trains.

In 1869, a French electrical engineer named Zénobe Théophile Gramme invented a dynamo; a machine that transforms mechanical movement into electricity and generates a continuous electric current. The Gramme dynamo surpassed other attempts of the time.

Almost all engines that have the current cars are called internal combustion engines. The first, armed in 1859 by the Belgian Etienne Lenoir, was running on gas. Later, German engineers Gottlieb Daimler and Karl Benz developed naphtha engines light enough to use in automobiles.

Photoelectric cells convert sunlight into electricity. They were invented in Germany in the 1890s. A few tiny solar cells can run a pocket calculator, and arranged in large honeycombs can generate electricity in homes and satellites.