There is this real life story about a cat and a British road-repairer and how their encounter changed the way roads appear to motorists. While at work on a foggy night in 1933, Percy Shaw happened to look into the eyes of a cat, and the ‘mystery’ he saw there steered him into a universally useful invention that was patented in 1934. And it answers a basic question: can a cat see in the dark?
Two types of cells make electrical signals out of the light that reaches the eye: cones and rods. The rods just switch off in daytime like our street lights, for they are more sensitive, and better suited in making the best of low light conditions. Cats have lots of rods, and their eyes let in more light anyway. What is mysterious (if any) about the proverbial feline vision is not this extra amount of light but what happens to it.
Something strange happens in your eyes when they confront a bright source of light. The black layer behind the retina is no more seen as black. A reddish colour replaces it. This comes from the nourishing blood vessels that are abundantly present in front of the “oxygen-hungry” retina. “Electronically” tricked by the brain, we fail to detect those blood vessels, but they light up well and cameras don’t miss them. This is how at times your photos are spoiled by those unsightly Dracula red eyes from camera flash. Cats survive it.
There is a kind of mirror, a layer called the “tapetum lucidum” behind the cat’s retina. This gives the animal an edge. In human eyes, if light that reaches the retina doesn’t hit a rod in its passage, it gets lost forever in the black layer at the back. But in a cat’s eye, light that is past this critical point will reflect off the mirror layer behind the retina, and so it gets a second chance to hit and register a rod.
Consisting of fifteen types of cells and highly reflective, the mirror gives a silvery-greeny-golden glow to the eyes of most cats, but it’s ruby-red in Siamese cats. It is this reflection that inspired Percy Shaw to invent his catseyes or “reflective road studs” and start to bulk-produce them in 1935. They still survive on roads to reflect the motor’s headlight back to the motorist — a success story with the tagline “from rod vision to road vision”, would you say!
SNEAK PREVIEW
POLES: GEOGRAPHIC AND MAGNETIC
People planning a trip to the North Pole in future might want to learn Russian. It seems that the Earth’s North magnetic pole is quickly (in the grand scheme of things) drifting away from Canada and into Siberia. The fact that magnetic north moves is not new. After the north magnetic pole was first discovered in 1831 by the British Navy’s James Clark Ross, explorers who revisited it in 1904 found it had moved fifty kilometres. But the geographic poles are simply where the Earth revolves on its axis, whereas the magnetic poles are governed by the magnetic field produced by the Earth’s liquid iron core.
WAS THAT AN INTELLIGENT PRODUCT?
A battle is raging in Kansas, USA, over a theory known as “Intelligent design”. It’s a Christian theory to advocate that everything in the world is as it is because some higher power made it that way, and Pope Benedict XVI diplomatically commented recently that the entire universe was an “intelligent project”. But not everyone in the Vatican agrees. Some remember that the Vatican played a role on condemning Galileo to house arrest hundreds of years ago, and then pardoned him in 1990, noting his theories were “in keeping with the teachings of the bible.”
QUIZ No.212
1. Is 2005 the hottest year in thousand years? If not, which years was it?
– It is 2005
– No, it’s 1869
– Did you forget 1734?
– Come on, it’s 1998
1. Come on, it’s 1998 (and 2005 is the second hottest).
2. Which feminist wrote a book about how ill-advised feminism harmed the boys?
– Carol Gilligan
– Sophie Treadwell
– Christina Sommers
– Susannah Heschel
2. Christina Sommers (‘The War Against Boys’)
3. Who will be the first woman passenger when Sir Richard Branson launches commercial space flights?
– Meg Mallon
– Sienna Miller
– Anna Kournikova
– Victoria Principal
3. Victoria Principal
4. What was Florence Nightingale’s second passion?
– Applied maths
– Composing music
– Flower arrangement
– Writing stories
4. Applied maths
3. Say “Hand of God” and you know it’s Maradona. Say “Goal No.1000” and you know it’s …
– Rinat Disaev
– Raymond Kopa
– Rob Rensenbrink
– Roberto Carlos
3. Rob Rensenbrink