I am, of course, talking about the
vacuum flask, invented by accident in 1643 by Evangelista Torricelli, when he was
trying to build the world’s first barometer, having previously created the
world’s first vacuum.
Torricelli did not invent the vacuum flask itself. It’s the concept that was his. In fact, the vacuum flask has been around for a
hundred years, invented by Cambridge
scientist Sir James Dewer in 1892 and patented in
1903 as the “Dewer Flask.”. The name was the result of a competition held in
Germany to come up with a title.
The product had been adopted by two German glassblowers who eventually awarded the
prize to a Munich resident who suggested “Thermos” from the
Greek word “Therme” meaning “hot.”
Since that time the vacuum flask has gone from
lifesaver in WWI trenches to style icon not out of place in an executive briefcase.
Thermos flasks were an immediate success. In an age when discovery was the watchword, no
expedition was complete without a Thermos. Shackleton took one with him to the South Pole,
whilst at the other end of the earth Robert E. Peary was enjoying his flask in the
Arctic . The Wright brothers carried one in their aeroplane
and Count Von Zeppelin’s flying machine included a Thermos too.
Memories of childhood picnics, days out to the seaside
and school lunch boxes jostle with visions of builders’ tea breaks and shivering
anglers at the very mention of Thermos – a brand name that has become virtually
generic.
“We have 99% brand awareness,” says Paul
Johnson, Thermos’ business development manager. “Even the French, who are
notorious for keeping their own language, call the vacuum flask ‘le
Thermos’.”
Vacuum flasks are simple enough in concept. The
best way to stop heat transfer is to create a barrier between contents and outside world.
Foam insulation will work for a while, but a vacuum cannot transfer anything, thus
preventing conduction and convection. The silvering on the glass inside a flask (or the
polished steel on the trendy new ones) reduces infrared radiation.
In the quest to balance vacuum and practicality,
traditional bugbears of weight and volume have seen the lining and casing becoming smaller
and thinner allowing greater capacities inside. In 1928 double-walled Pyrex® glass was used to create
a twenty-eight gallon monster, popular with ice cream parlours and fishmongers.
But it is with domestic users that the humble
vacuum flask has found its niche. From the introduction of the pint-sized “Blue
Bottle” in the early 1920s, it has found a place in the heart of every secretary,
builder’s mate and film star – W.C. Fields famously sipped martinis from his.
Styles have changed – my family
had a tartan one in the sixties, a
charming tin-cased affair topped with a cream plastic lid doubling as a cup. Handles came
slightly later, along with funky 70s flowers and geometric patterns – examples of
which change hands in antique markets today for around £20.
For the last twenty years or so, moulded plastic
with a silvered glass interior has been the standard. “It’s like an old
mate,” says Derek Murphy, patting his green plastic moulded Thermos which has
accompanied him to building sites all over the South East for the last seven years.
“It comes with me wherever I go and is more faithful than my dog.” Somewhat less
faithful himself, Derek has his eye on one of the new stainless steel varieties.
There’s definitely a swing
towards the brushed steel “bullet” styles,” says Paul Johnson.
“It’s not entirely due to aesthetic reasons
though – they are safer, have better heat retention and now that steel prices
are tumbling they are cheaper too.”
Sara Davey, buying manager at the Cookshop in
Selfridges in London has also noticed the huge increase in sales in stainless steel
this year. She says. “We
stock two kinds – Thermos and Elia, and our top sellers in each brand are stainless
steel. This year I’m introducing a Light and Compact from Thermos which is in a
rather nice powder-blue steel and meant for people who are out and about. Then I’m
going to the other extreme with the “work” series. They’re tough. They look very traditional – the
whole retro thing is very big just now. There’s one called “The Rock” which
keeps liquid hot for up to 24 hours.”
Internet survival guru Kurt Saxon claims that an
entire family’s cookery can be done using vacuum flasks. “Save on wood, weight
of food carried, and food odours to alert bears or enemies,” he enthuses, cheerily
advising how to create 1½lbs of “dessert” for 46 cents. More discerning web
surfers might prefer to investigate www.thermosonline.com
offering a titanium version for a mere $129.
Vacuum flasks have carried everything from rare
tropical fish to blood, bones and insulin, in ‘planes at high altitudes. But by far the most popular contents are tea and coffee. Some complain that
flasks impair the taste, but John Rickaby of specialty coffee company Café Origin
disagrees. “Obviously fresh coffee is preferable,” he says, “but whereas a
traditional hotplate will just “stew” coffee, a good quality vacuum flask will
slow the rate of deterioration.” Chris Wright,
from tea merchants London Cuppa has other ideas. “The best way is to bring the hot
water in the flask and then make the tea on the spot – it’s not
hard to bring a few teabags. And carry milk in a separate container. ”
 But what of Evangelista Torricelli’s
invention? Well, he suffered for his service to flask-kind. The Renaissance Church
declared that since God was omnipresent there could be no such thing as a vacuum.
Torricelli was declared a heretic and ultimately buried in an unmarked grave.
A version of this article first
appeared in the Times newspaper
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