| 2521/
In about AD 130 Ptolemy added the letter 'omicron' as a zero
to the Sumerian number system based on 60, but this fell into
disuse. The starting point for the zero in use today was in
India. In the seventh century Indian mathematicians often
used a word to denote the absence of a number in their place-value
decimal syetem (so avoiding confusion of, say, 305 with 35
or 350). This was represented as a dot, which developed into
a recognisable zero symbol.
2522/ In 1202 the Italian
mathematician Leonardo of Pisa (nicknamed 'Fibonacci') published
his Liber Abbaci, which popularized the new arithmetic
of the 'nine Indian numerals' and the 'zephirum' or 'zero'.
Fibonacci devoted considerable space to mercantile mathematics,
and an industry for professional 'calculators' developed to
handle financial calculations. The first printed book on accountancy
was Luca Pacioli's Summa Arithmetica (1494), and books on
financial and navigational calculations became very popular
in ports throughout Europe.
2523/ Atmospheric Pressure,
the weight of the air above the surface of the Earth; means
that it is possible to pump water to a hight of almost ten
metres but no higher.
2524/ Carolus Linnaeus,
a Swedish Naturalist and Physician, published his system of
nomenclature in Systema Natura in 1735. His method of referring
to species works so well that it has been used, unchanged,
for two and a half centuries. Biologists refer to a species
by a Linnaean two-part name, such as Equus caballus,
which is the formal title for the domesticated horse. The
first of the two words (Equus) always takes an initial
capital and is the name of the genus; the second (caballus)
always takes lower case and is the name of the species. A
genus may contain more than one species: the plains' zebra,
for example is Equus burchelli, but the combination
of both names is unique to one species.
2525/ Although Joseph
Priestley first observed Oxygen in 1774. It was actually named
by French Chemist Antoine Laurent Lavoisier. Who in 1777 gave
the gas its name: oxygene, meaning 'acid-former',
as he believed it (wrongly) to be the fundamental constituent
of all acids.
2526/ Following a 14-year
mass vaccination campaign, the World Health Organisation announced
in 1980 that smallpox
had been eradicated once and for all. The last case of smallpox
in the United States was in 1949. The last naturally occurring
case in the world was in Somalia in 1977.
2527/ On 21st July 1820
the Danish Physicist Hans Christian Oersted published a six-page
paper in Latin announcing his discovery of electromagnetism.
While lecturing to a class of students, he had noticed that
a compass needle is deflected when brought close to a wire
carrying an electric current.
2527/ On the 29th August
1831, a laboratory director at the Royal Institution in London,
Michael Faraday, succeeded in turning magnetism into electricity.
He wound two coils of wire on opposite sides of a soft iron
ring. When a current passed through one coil, the ring became
magnetized and momentarily induced a current in the other
coil. This was in effect the first electric transformer. Within
six weeks, Faraday had also invented the dynamo. Here a permanent
magnet is pushed and pulled through a coil to induce an electric
current in the wire. All generation of electricity to this
day, no matter what the primary source of energy, is based
on this principle.
2528/ Charles Lyell's,
Principles of Geology, was first published as three
volumes between 1830 and 1833, selling more than 15,000 copies
and eventually running to eleven editions (the last in 1872).
Clearly and attractively written, the first volume famously
served as a 'Beginner's Guide to Geology' for Charles Darwin
when he set sail on the Beagle on 27th December 1831.
2529/ In 1842 the British
anatomist Richard Owen coined the term 'dinosaur' ('terrible
lizard') and its scientific category 'Dinosauria' to distinguish
recently discovered fossils of the giant reptiles Iguanodon
and Megalosaurus from known living reptiles. With
his taxonomic trick, Owen stole the initiative from Gideon
Mantell and William Buckland, who had first discovered and
described the giant reptile fossils.
2530/ Charles Darwin
conceived natural selection in the 1830s, but waited 20 years
before publishing it - and then because another British naturalist,
Alfred Russel Wallace, had independently developed much the
same theory and presented it to Darwin. Darwin and Wallace
jointly published the theory in 1858, but eveolution and natural
selection were little noticed until Darwin's Origin of
Species came out a year later. Only 1,250 copies were
printed, and every one was snapped up on the first day of
publication.
2531/ Crops planted in
soil in which beans have recently been grown produce higher
yields. The reason for this is that the roots of beans have
nodules housing bacteria that convert atmospheric nitrogen
into a form that plants can use for growth.
2532/ Enzymes are natural
catalysts that increase the rate of chemical reactions. Perhaps
the most popular example is found in the brewing industry
in which sugars are converted into ethyl alcohol and carbon
dioxide by the action of enzymes secreted by yeast cells.
2533/ The word 'virus'
is Latin for 'poison'.
2534/ The Austrian Karl
Lansteiner made blood transfusions safe. In 1900 he found
that a sample of human serum 'clumped' red blood cells from
some people but not others. He suggested in 1901 that the
clumping was due to the reaction of 'antibody' molecules in
the recipient's serum with 'antigen' molecules on the surface
of the donor's red cells - antibodies are proteins that defend
the body from foreign substances. He concluded that there
were two related antigens, A and B. Some cells carried A,
some carried B, some carried both and some carried neither.
Hence the four blood groups, A, B, AB and O. Since that time
other blood groups have been described, but the principle
is the same.
2535/ In 1961 Edward
Lorenz accidentally found a mathematical system with chaotic
behaviour in a computer model of the atmosphere. Small changes
in the initial conditions produced wildly different, and so
completely useless, long-range weather forecasts - a phenomenon
that became known as the 'butterfly effect'.
2536/ Albert Einstein
explains Relativity:
"When a man sits
with a pretty girl for an hour, it seems like a minute. But
let him sit on a hot stove for a minute - and it's longer
than any hour. That's relativity."
2537/ Applying relativity
to the idea of energy, Albert Einstein discovered his most
famous equation E = mc². It means that there is energy
hidden in matter - a huge amount of energy; equal to the object's
mass times the speed of light squared. A kilogram of anything
holds enough energy to boil a hundred billion kettles. Or
destroy a city.
2538/ The word 'vitamins'
derives from 1912 when Casimir Funk called the 'accessory
food factors' that were being investigated by English bio-chemist
Frederick Gowland Hopkins at the time - 'vitamines' - from
'vital amines'. This was because he believed they were chemically
(the 'e' was dropped when it turned out that not all vitamins
were amines). As each vitamin was identified and isolated,
researchers gave it a new letter, although several vitamins
are in fact groups or complexes of different compounds.
2539/ James
Usher, Archbishop of Armagh, Ireland, (1581-1656), used
Judeo-Christian texts to date the Creation at 4004 BC. This
date was widely accepted and even printed in the Bible as
an historic truth - and was still being quoted in the infamous
anti-evolution Scopes
trial in America in 1925.
2540/ Cosmic
Rays from outer space account for around 15 per cent of
the average person's natural radiation dose and probably cause
more than a hundred thousand fatal cancers per year.
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