Luminous objects are responsible for our vision.In complete darkness we cannot see  the different objects around us. Human eye perceives the light reflecting from different objects to cause the sensation of vision. Luminous intensity,  the quantity of visible light that is emitted in unit time per unit solid angle. The unit for the quantity of light flowing from a source in any one second.

The extraordinary scientific family — the ‘Lighthouse Stevensons’ — built 97 ligh_51039637_jex_942243_de29-1thouses round the coasts of Scotland from 1790 to 1940. The Scottish poet Kate Clanchy told me after a Royal Society of Literature lecture on Sargent’s little masterpieces. The Bell Rock Lighthouse, off . The Light is visible from 35  statute miles inland. The masonry work on which lighthouse was constructed is such a high standard that it has not been replaced  in 200 years. That’s really surprising.

There were so many challenges which were faced during the time of building lighthouse .  Even it is  being described as one of the Seven Wonders of the Industrial World.Stevensons were tinkering  away the lighthouse lights years before. Robert Louis Balfour Stevenson was a Scottish novelist, poet, essayist, and travel writer. His most famous works are Treasure Island, Kidnapped, and Strange Case of Dr Jekyll and Mr Hyde.