In Jules Verne’s story The Desert of Ice, Captain Hatteras
and a few loyal men were abandoned near the
mutinous crew during an attempt to reach the North Pole.
Although the abandoned men possessed wood for a fire,
they lacked any sparking materials or other means by
which to ignite the wood. Faced with a long trek over the
ice field to reach another ship, the abandoned men knew
that they would soon freeze to death. However, the ship’s
doctor hit upon a scheme by which ice could be made to
ignite kindling. Can you guess how? Will such a technique
actually work?
Answer According to the story, the doctor fashioned a
convex lens from a clear section of ice (it lacked air bubbles
normally trapped in ice during the freezing process).With a
hatchet he chopped out the section and roughly shaped it.
Then he smoothed it with his knife and the warmth from his
fingers. As he held the ice lens in the bright sunlight, he
adjusted its height so that the point of concentrated sunlight
(the focus) was positioned on the kindling. Within seconds,
the kindling ignited.
The idea for this scheme may have originated with
William Scoresby, a noted British scientist who is remembered
for his pioneering
his roughly formed lenses of transparent ice could ignite
wood, melt lead, and light a sailor’s pipe. More recently,
Matthew Wheeler of McBride in
how he took photographs with a camera using an ice lens
instead of its normal lens.
You might also be able to start a fire with a lens in common
eyeglasses. If the lens is designed for someone who is
farsighted, it has a focus that can be positioned on kindling.
However, if the lens is designed for someone who is nearsighted,
the lens does not focus the rays. Thus, the fire-starting
story in The Lord of the Flies is flawed: Piggy is very
nearsighted, and Ralph could not have ignited wood with the
eyeglasses as described.
Taken From "The Flying circus o Physics".
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