Random reminder

Press, 13 September 1988, Page 29

Random reminder

TWEETNESS AND LIGHT

There is a lot of power in sunlight, as you would expect from a fusion reaction only eight light-minutes away. As well as inspiring personkind to develop the fusion bomb — a sadly temporary and short-lived effort, compared to what can be found in the cosmos, which comment may also turn out to be true of personkind — all that energy has inspired personkind to develop the Thermonuclear Teas-maid, or solar kettle. One kilowatt of free heat per square metre, bounced off an umbrella lined with foil, can bring a pot to the boil faster than you can say Ouch if you get your hand caught in the beam. Anyone can pass their hand through a flame quite slowly, for the dry heat is conducted slowly. Steam causes worse and quicker injury, for the enormous energy difference between steam and boiling water is quickly transferred to whatever that boiling water covers. Even

so, there is from domestic kettles a certain amount of hiss and puff which gives you warning. Radiant heat gives you no warning. Fireworks fans will remember how Lucifer Pyrotechnics (our local firm) sets off acetylene flares. Pop! And all the upturned faces flinch, and think of shadows etched on tile.

Anyhow, our experimenter copied a solar kettle that she saw in a shop window, and' tried it out on a family picnic. She slotted the bits together, aimed it at the sun, and lifted the kettle up to the OUCH!

Mild heat over a square metre becomes 400 times stronger when it is focused to saucer size. She burnt herself.

“You dillbrain!” snapped her mother a few minutes later. “You have melted the handle and lid of the kettle, and it is not even foiling.” ... 1 - - ----- -