Focused sunlight. Engraving of an experiment to focus sunlight devised by French scientist Georges Louis Leclerc (1707-1788), Comte de Buffon. Buffon (wearing a hat at upper left) had read of the defence of Syracuse, Italy, by Greek scientist Archimedes (287-212 BC). Archimedes had supposedly used mirrors and the Sun's rays to set fire to the attacking Roman fleet. Buffon used 168 mirrors, each measuring 15 centimetres (cm) by 20 cm, to successfully ignite wooden logs at a range of 50 metres. He concluded that Archimedes' could have actually defended Syracuse in this way. Today, light produced by lasers is used to heat, melt and vaporise substances.