What are SPLATs? They are explained here.
More to come...
The technology of agriculture
- Humans have been practising agriculture for about 10,000 years after
 agriculture was independently invented in at least Mesopotamia, America
 and New Guinea.
- For all that we know, there may have been other independent
 inventions of agriculture in other societies, but so far, we have no 
evidence of this.
- The development of agriculture allowed humans to settle in 
one place and so have better shelter, and also own more possessions than
 they could carry around.
- Farmers were generally able to produce more food than they 
and their families needed, and this opened the way to some people being 
able to specialize.
- Some parts of the farming cycle left farmers with nothing 
to do but watch their crops grow. This gave them time to think, to 
observe, and perhaps even tinker.
- Farmers were able to observe the same basic situation, year
 by year, with slight differences that allowed them to observe cause and
 effect at close hand.
- One of the key changes that allowed agriculture was the 
development of systems of irrigation, but these required more organized 
societies to maintain them.
- The aqueduct was an early means of transporting water with 
no energy cost, using gravity to carry the water, although inverted 
siphons were also used at times.
- The aqueduct could work by gravity when builders could 
survey a suitable route, build supports and construct a waterproof 
channel to carry water without leaks.
- The qanat of ancient Persia was an early means of 
transporting water with no energy cost, relying on a tunnel going 
upwards, beneath the water table in hills.
- Irrigation, combined with agriculture, delivered regular 
food surpluses allowing some people to specialize in making things that 
they could sell or barter.
- Irrigation and agriculture together led to a society in 
which some people could become full-time soldiers and rulers, while 
others could become scholars.
- In 1630, Johann Glauber suggested the use of saltpeter, 
sodium nitrate, as a fertilizer, implying a recognition of the need for 
nitrogen when growing plants.
- In 1645 Sir Richard Weston described crop rotation as he 
saw it in Flanders: the first reference in English to the habit of using
 different crops in one field.
- Around 1701, Jethro Tull invented the seed drill, allowing 
farmers to sow seed more efficiently and more economically, increasing 
the efficiency of large farms.
- Most crops are grown as monoculture crops, making massive 
outbreaks of pests easier, but offering large economies of scale. Sprays
 make the risk less.
- Most sprays kill more than just the pests they are aimed 
at. Many of the pesticides are accumulated to dangerous levels, either 
in the soil or the food chain.
- Many organohalogens are used as pesticides in farming, and 
the use of these pesticides in agriculture is driven by a consumer 
demand for blemish-free food.
- Overgrazing can be a problem in some situations, trading 
off long-term viability of a farm for short-term gain by a farmer. 
Economic pressures may favor this.
- In many cases, the energy output from a farm in the form of food is less than the energy input in terms of materials like fertilizer and pesticides, and fuel.
The principles of materials science
- Materials have a measurable elasticity: metals are highly elastic 
and commonly have high tensile strength, which is the reason why wire 
cables are so strong.
- Materials can have either or both of two forms of strength:
 strength in compression or strength in tension. Most materials have 
only one of the two strengths.
- Many constructions combine two phases, one material with 
compressional strength, one material with tensional strength, like 
reinforced concrete or fibre-glass.
- Materials are usually selected to suit the purpose they are
 to be used for, while two-phase materials combine the advantages of two
 different materials.
- Structures are designed to stay up, and they do so because 
they distribute stress and load in a way that allows all components to 
be supported and held.
- Arches transfer loads and reduce stress in gap-spanning 
structures such as bridges, and a cantilever can be used to support a 
projecting structure.
- The aim of the arch is to convert tensional forces to 
compressional forces, as these are usually easier to manage when people 
are working in stone.
- Stone is a material which can withstand large forces of 
compression, but it can be shown to be not so strong when it is placed 
under tension.
- Cathedrals and mosques were early structures targeting a 
large floor space with no columns to block views. This led to a better 
understanding of engineering.
- Large structures like cathedrals, mosques and bridges 
achieve large spans by transferring the loads to where they can be 
handled by the materials used.
- Any pure material has a characteristic constant density. 
Density is determined by differences in packing of particles and atomic 
mass and radius.
- Robert Hooke proposed what we now refer to as Hooke's law 
in these words: The power of any Spring is in the same proportion with 
the Tension thereof.
- In 1744 Leonhard Euler calculated the length of a rod that will buckle under its own weight when stood on one end, indicating that materials have their limits.
The principles of measurement science
- Old units of measurement include the grain and the line, the yard 
and other units which were at best poorly-defined and which varied from 
place to place.
- In 1832, Karl Gauss pointed out that a few fundamental 
units, once defined, could be used to generate many more derived units 
in a consistent system.
- Around the world, SI units are the standard units of 
science, based on the meter, kilogram, second and ampere and a variety 
of combinations of these units.
- Many of the things that we measure are scalar quantities, 
having a value but no direction component, like length, speed, but not 
velocity, and mass.
- Some of the things that we measure are vector quantities, 
having both a value and a direction aspect, like velocity (but not 
speed) and acceleration.
- We can use various observations taken from a distance to 
measure where we cannot go, so that we can measure the distance to the 
Sun, or its temperature.
- One of the standard units of astronomical distance is the 
light year, the distance that light could travel in one year at 300,000 
kilometres per second.
- All measuring instruments operate within limits of 
accuracy, and when several different measurements are combined, the 
possible error is increased.
- Indirect measurements of values like the distance to the 
Sun or the Sun's temperature, are more open to error, because of the 
indirectness.
- A correlation between two measurements that seem to vary 
together does not indicate with any degree of certainty that one of them
 causes the other.
- In 1784, Charles Coulomb described the operation of the 
torsion pendulum, later used to measure very small electrostatic and 
gravitational forces.
- Before electronic surveying equipment, a chain was commonly
 used to measure a long baseline, from which sightings were then taken 
on prominent landmarks.
- Given time and patience, it is possible to use a theodolite
 and chain to take enough measurements of bearings and distances to map a
 whole continent.
- The process of mapping by chain and theodolite involved 
building a sequence of triangles linked together, so it was called 
triangulation.
- Classic major surveys were done by Mason and Dixon 
(America), John McDouall Stuart (Australia) and assorted French 
scientists in France, Lapland and Peru.
- Some of the key mapping exercises were to measure the 
length of a degree at different latitudes on the Earth's surface, some 
at the equator, some further north.
- Once the degree had been measured at different latitudes, 
scientists knew the true shape of our planet was not a sphere, but more 
like a flattened sphere.
- Very large distances on land can be measured using radar 
and similar signals, much more easily than the old survey method of 
'chaining' the distances.
- The Fahrenheit scale was designed to avoid any temperature 
that was negative, since Fahrenheit felt ordinary people could not cope 
with negative numbers.
- Until there were reliable thermometers to use, it was not 
possible for scientists to recognise the important difference between 
heat and temperature.
- Temperature may be measured as absolute temperature on the Kelvin scale. It is possible to approach a zero temperature, but it cannot be reached.
The principles of time measurement
- A sundial can be accurate, within limits such as fuzziness of the 
shadow, variations in day length, and the annual 'equation of time' 
which must be allowed for.
- Slow-burning candles, protected from draughts, can be used 
as clocks at night and on cloudy days, and have been used since the days
 of the Anglo-Saxons.
- The Julian calendar was used until the Gregorian calendar 
was adopted: the Julian calendar was well out of synchronization with 
the seasons by that time.
- Christiaan Huygens invented the pendulum clock around 1655,
 and patented it in June 1657, introducing a new standard and opening 
the way to chronometers.
- Pendulum clocks use the uniform motion of a pendulum to 
produce an accurate timekeeper, although the rate varies with small 
variations in gravity.
- An accurate mechanical clock needs a good escapement, a 
device which converts the rhythmic movement of something such as a 
pendulum to equal steps.
- Clocks such as pendulum clocks which can be affected by 
expansion in warm weather often have Invar parts, or other compensation 
systems to allow for expansion.
- Water clocks can be calibrated: the earliest form of water 
clock was the klepsydra of the ancient Greeks, but many cultures have 
used water clocks.
- An effective water clock was used in Indonesia, in the 19th
 century, made by sitting a half of a coconut shell with a small hole in
 it, in a bucket of water.
- The Julian date is a day-numbering system used in 
astronomy, and it is entirely unrelated to the Julian calendar. It 
counts days from January 1, 4713 BC.
- Time around the world is based on Greenwich Mean Time, and 
time zones are defined by their time relative to that time zone, usually
 in one-hour jumps.
- Accurate time zones and consistent times within zones were 
not essential until the world began to be linked by railways and 
telegraphs and needed standards.
- Occasional leap seconds are used to align planetary time 
with clock time, as these are not always precisely the same. These are 
applied when they are needed.
- The solar day differs from lunar and sidereal days which 
are defined by the time taken for the Sun, the Moon and a star to reach 
the same position again.
- Our understanding of the Earth's history comes from the 
science of geological dating, which has allowed us to place geological 
events in a rough order.
- Tree growth rings are useful for measuring time over a few 
hundred to a few thousand years, relying on patterns of thickness that 
reflect good and bad seasons.
- Most living things have internal 'clocks' that operate on a
 cycle of approximately 24 hours, and kept in alignment with real days 
by exposure to light.
- Humans suffer 'jet lag' when they travel too far east or 
west, if the extent of the travel is too great for the internal clock to
 realign itself immediately.
- Jet lag shows up in human beings as wakefulness in the 
night and sleepiness in the daylight hours that correspond with night 
time at the point of origin.
- Studies of the Earth have led to a consistent geological time scale that reflects a wide variety of measures from many different branches of science.
The principles of navigation
- Navigation is the art of knowing where you are on the surface of the
 globe. It is an ancient art that has largely been replaced with 
technology in recent times.
- As late as the 20th century, celestial navigation relied on
 the observer being able to see the sun, the moon, or stars at exactly 
the right time.
- Latitude can be measured by taking sightings on the sun or 
stars, although it is mostly done today by GPS hardware that relies on 
the locations of satellites.
- Simple interference in the form of fog, cloud, mist, or 
being busy when deciding was to be taken, could cause a 24-hour delay in
 getting an accurate position.
- Longitude can be measured best with a good chronometer, so 
you can relate your present position to the reference position from 
which longitudes are measured.
- Longitude may also be measured by careful observation of 
the moon and using tables, but this is an unreliable method, especially 
when a ship is moving.
- In 1735, John Harrison built his first marine chronometer 
(Number One), designed to win the award of the British Board of 
Longitude for an accurate time keeper.
- In 1759 John Harrison completed his fourth chronometer 
(Number Four), which would eventually gain him the Board of Longitude's 
prize for accurate time keeping.
- In 1761 John Harrison's portable chronometer (Number Four) 
was successfully tested on a trip from Britain to the West Indies and 
back, proving itself at sea.
- The quadrant was an early navigational instrument with limited use.
- The sextant was an early navigational instrument with 
limited use, but it was able to give remarkably accurate results when 
latitude needed to be found.
- A compass is needed to make sure a boat sails in the right 
direction, once it is out of sight of land, although radar and GPS 
equipment are more reliable.
- One of the drawbacks of the old magnetic compass was that 
it tended to swing around when used on a small rocking boat. Oil damping
 fixed this.
- One of the drawbacks of the old magnetic compass was that 
it relied on a magnetic field that was not uniform in its direction from
 place to place.
- Edmond Halley experimented with the use of charts of 
magnetic deviation, the difference between true and magnetic north, to 
find longitude around the world.
- Between 1783 and 1824, the national Ordnance Survey of 
England, mapped all of Britain, except for the eastern part of England 
and north-west Scotland.
- The main role of the people we call Australian explorers was to work across Australia, surveying the series of triangles to map the continent by triangulation.
The social effects of technology
- Technology is much older than science: once, science was derived from new technology, today, it is more likely that technology will be derived from new science.
- Alan Kay's point that the only way to predict the future is to invent it remains valid. History has too many examples of impossibles that became possible.
- Every technology that has ever been developed has been attacked by people who see it, usually irrationally, as threatening their way of life in some way.
- Every technology, having been developed, has had social effects and consequences that could never have been anticipated when it was first introduced.
- Most new technologies have been dismissed as useless and dangerous nonsense by at least one elderly and experienced scientist who knows all about the subject.
- Many pieces of useless and dangerous nonsense have been correctly attacked and dismissed for what they are by at least one elderly and experienced scientist.
- That which scientists dismiss as impossible is only so under a set of assumptions and knowledge that are always open to revision, question and change.
- A new technology typically goes through a twenty-year development phase before becoming generally adopted and maturing over the next thirty years.
- At the end of the fifty years of development and maturation that all technologies seem to need, the social effects of the new technology start to become apparent.
- Technology is neither good nor bad. In the long run, every technology improves the lives of humans, but it can exact an incredible toll upon some human beings.
- These days, there is never enough appropriate technology, using small solutions to tackle and crack small problems at a local level with simple equipment.
Simple machines
The principles of forensic science
- Humans vary in many ways, and leave hints of these variations 
behind at the scene of a crime, in the form of prints, stains, traces 
and impressions.
- People who visit a particular location don't only leave 
traces of themselves at the site, they generally take traces of the site
 away with them.
- In 1860 Sir William James Herschel used fingerprint 
impressions made on paper to provide reliable identification of 
individual government prisoners in India.
- In 1890, Francis Galton began his study of fingerprints. 
Originally, he was looking for racial differences in fingerprints, but 
failed to find any.
- Francis Galton was able to show that human fingerprints 
stay the same throughout the owner's life, so doing away with the 
physiognomy of Cesare Lombroso.
- Individuals may be distinguished by DNA fingerprinting, but
 this remains less than totally reliable, as related people can have 
similar patterns.
- Individuals may be distinguished by DNA fingerprinting 
which looks for unique aspects of the DNA found only in an individual 
and his or her relatives.
- DNA fingerprinting is unreliable in cases where more than one member of a family or related community is under suspicion, since they will have similar profiles.
- The credit for an invention does not always go to the first person 
to invent it, but to the first person to patent it or associate their 
name with it.
- In 1813, a methane explosion in a mine at Gateshead-on-Tyne
 killed 92 miners, making the British public very aware of the problems 
of coal mine explosions.
- George Stephenson invented a safety lamp for miners at the 
same time as Sir Humphry Davy, who called Stephenson "a thief, and not a
 clever thief".
- Humphry Davy is remembered today for his miners' safety 
lamp, which let the coal-miners see what they were doing without making 
methane explode in the mines.
- Stephenson was given a reward of one thousand pounds, and a
 House of Commons select committee found in his favour, but the lamp is 
still the Davy safety lamp.
- In 1836, Edward Davy invented the electrical relay in 
London, so as to make a telegraph work over distances, but he later sold
 the patent and went to Australia.
- The Bunsen burner was probably invented by Peter Desaga, a 
technician in Robert Bunsen's laboratory, but neither of them applied 
for a patent on it.
- Later, Carl Desaga, Peter Desaga's son, founded a company, 
C. Desaga, Factory for Scientific Apparatus, to make and sell the 
burners, all over the world.
- André Ampère was an inventor of things, but also a great 
coiner of names: his invented words include 'electrodynamic', 
'electrostatic' and 'solenoid'.
- Alexander Graham Bell only just managed to lodge his patent
 claim for the invention of the telephone before Elisha Gray lodged a 
lesser caveat claim.
- Thomas Edison invented many things, mainly by seeing a need
 and then trying large numbers of solutions, improving as he went, until
 he had something to sell.
- Thomas Edison and Joseph Swan both invented electric light 
globes at almost exactly the same time, and coming up with similar 
solutions to the problem.
- Thomas Edison observed the thermionic effect, but failed to realise that it had potential in electronics, even though he took out a patent on the effect.
The principles of printing
- Around 1450, Johannes Gutenberg introduced the use of moveable type 
in printing, allowing books to be produced in large numbers to supply a 
growing market.
- In 1478, the first printed medical work appeared, a version
 of the 'De Medicina', the medical views of a 1st century Roman 
physician, Aulus Cornelius Celsus.
- Albrecht Dürer wrote his book of the methods for achieving 
correct perspective in German, but a translation into Latin carried his 
ideas to the rest of Europe.
- In 1543, 'De Humani Corporis Fabricae', the first modern 
work on anatomy, was published by Vesalius, bringing a modern light to 
medicine for the first time.
- In 1556, Agricola published 'De Re Metallica', which not 
only described the methods of metallurgy, but also of mining, and so 
dealt with questions of geology.
- In the early 1600s, Galileo Galilei was one of the first to
 write about science in his local tongue, rather than in the Latin that 
scholars had used until then.
- In the middle of the 1600s, scientists began showing each 
other what they had discovered (and how), and began to publish notes for
 absent members.
- In time, the published 'proceedings' of the various 
societies began also to include letters sent by distant members, 
widening the scientific networks a great deal.
- When the various national societies began to exchange 
copies of their published proceedings, modern science was able to really
 take off, all over the world.
- By the late 1600s, most scientists wrote of their work in 
their own languages, rather than Latin. Hans Oersted, in 1820, was one 
of the last who wrote in Latin.
- In late 1788, Gilbert White published his Natural History 
of Selborne, introducing a new style of studying nature, and changing 
the way people saw nature.
- In 1830, Charles Babbage published his Decline of Science 
in England. This stimulated the formation of the British Association for
 the Advancement of Science.
- In 1845, the magazine Scientific American was established 
as a way of sharing news about science and technology with the general 
public. It opened a new era.
- In 1869, Norman Lockyer became the first editor of the 
scientific journal Nature, which has remained one of the great journals 
of science ever since.
- Around 1800, the first subject-related scientific journals 
began to appear, dealing with limited topic ranges, rather than general 
magazines of curiosities.
- Valid new science will now normally be published in a 
peer-reviewed specialist journal. Claims which are published in other 
ways have to be regarded as suspect.
- Some valid new science may also be presented at 
conferences, where other scientists are able to comment on it: much of 
it will also appear later in a journal.
- In the middle of the 20th century, Marshall McLuhan wrote several books to bring us the message that the book was dead. One day, we will see he was right.
The science of images
- Around 1520, Albrecht Dürer was using mechanical arrangements to get
 accurate perspective into his drawings, and published a book for 
artists on his methods.
- In 1727 Johann Schulze saw that some silver salts go black 
in the presence of light, setting the basis for photography, although it
 would take a century more.
- James Clerk Maxwell showed in 1861 how he could reproduce a
 tartan from three separate filtered photographs, red, green and blue, 
when these were recombined.
- The thing Maxwell had not allowed for was the total 
inability of the films of the day to react to red light. In short, the 
experiment should not have worked!
- The red dye in the tartan also reflected ultraviolet light,
 and by luck, the film used to record the 'red' component also 
registered UV, and so made an image.
- In 1973, Fairchild semiconductor released the first large 
image forming CCD chip which had 100 rows and 100 columns, a forerunner 
of the digital camera.
- In 1982, compact discs, CDs, were introduced, first as a 
means of storing and recording music in digital form. Other digital 
applications soon followed.
- Holography is a process that relies on interference effects
 to create 3D images with coherent light after the interference patterns
 have been captured on film.
- Sonar uses reflected sound to locate objects. Ultrasound is
 similar in its operation, but it uses reflected high-pitched sound to 
locate objects.
- Magnetic resonance imaging (MRI) is a method used to form 
images of the inside of a living thing without any risk of tissue damage
 from radiation effects.
- MRI creates images by detecting hydrogen atoms, mainly in 
water, but also in other molecules in the body, with a clever use of 
radio frequency radiation.
- Computerised tomography or CAT scans provide 3D images from X-rays, after massive computer processing has been applied to data to produce simple images.
The principles of transport (stub)
- In 1662 Blaise Pascal proposed a horse-drawn public bus which had a 
regular route, schedule, and fare system, which started its operations 
in 1663.
- Early in the Industrial revolution, it was important for 
factories to be close to sources of power, and close to rivers and 
ports. With time, that changed.
- Canals were extensions of rivers, waterproof channels that 
mostly followed contour lines and allowed goods to be moved in all 
weather with minimal breakages.
- Canals were an effective way to move goods before rail and 
road, offering smooth travel, and a low-friction path, where a single 
horse could move large loads.
- The steam turbine was a more compact and powerful unit, 
leaving more room for cargo, and moved the ship faster and more 
reliably, thus revolutionizing shipping.
- The internal combustion engine is used in most mobile applications. It is inefficient and noisy, but highly convenient, and its fuel can be obtained anywhere.
The principles of military technology (stub)
- The introduction of cannon into warfare meant that walled cities and
 towns were of no great use, and opened the way to open cities and towns
 with suburbs.
- Around 1500, Leonardo da Vinci was designing and possibly 
making a variety of mechanical devices and siege engines to carry out a 
variety of warlike functions.
- Most of the work done on developing rockets was done on military budgets, mainly by people like Robert Goddard and von Braun, who just wanted to get into space.
Nanotechnology (a stub)
- Nanotechnology is the art of making very small machines that will 
perform useful functions. Some methods are known, no useful functions 
have been achieved yet.
- Nanotechnology is new and little understood, but that has 
not stopped people from coming up with all sorts of 'Frankenstein' and 
'grey goo' scenarios about it.
- At the moment, nanotechnology is easy to dismiss or rule out, but there are some interesting developments around that will be used somewhere, at some time.
 
 
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