A letter published anonymously by Scots' Magazine in 1753 is the earliest description of a method for transmitting text using wires. The invention described in the letter used 26 parallel wires, one for each letter of the alphabet. The sender would place a static electric charge on each of the wires in turn and at the receiver's end the charged wire (with a small sphere at the end of it) would attract a piece of paper which had the corresponding letter marked on it. In this way a message could be spelt out and be read at the other end virtually instantaneously.
While practical telegraphs which came into use a century later used Morse code to transmit messages over a single wire, parallel systems are still very common today (although they use compact binary encoding rather than a very wasteful one wire per letter). A good example is the parallel cable that connects to your printer.
Sir: It is well known to all who are conversant in electrical experiments, that the electric power may be propagated along a small wire, from one place to another, without being sensibly abated by the length of its progress. Let, then, a set of wires, equal in number to the letters of the alphabet, be extended horizontally between two given places, parallel to one another, and each of them about an inch distant from that next to it. At every twenty yard's end, let them be fixed in glass, or jeweler's cement, to some firm body, both to prevent them from touching the earth, or any other non-electric, and from breaking by their own gravity. Let the electric gun-barrel be placed at right angles with the extremities of the wires, and about an inch below them. Also let the wires be fixed in a solid piece of glass, at six inches from the end; and let that part of them which reaches from the glass to the machine have sufficient spring and stiffness to recover its situation after having been brought in contact with the barrel. Close by the supporting glass, let a ball be suspended from every wire; and about a sixth or an eighth of an inch below the balls, place the letters of the alphabet, marked on bits of paper, or any other substance that may be light enough to rise to the electrified ball; and at the same time let it be so contrived, that each of them may reassume its proper place when dropt.The identity of the letter's author has never been determined.
All things constructed as above, and the minute previously fixed, I begin the conversation with my distant friend in this manner. Having set the electrical machine going as in ordinary experiments, suppose I am to pronounce the word Sir; with a piece of glass, or any other electric per se, I strike the wire S, so as to bring it in contact with the barrel, then i, then r, all in the same way; and my correspondent, almost in the same instant, observes these several characters rise in order to the electrified balls at his end of the wires. Thus I spell away as long as I think fit; and my correspondent, for the sake of memory, writes the characters as they rise, and may join and read them afterwards as often as he inclines. Upon a signal given, or from choice, I stop the machine; and, taking up the pen in my turn, I write down whatever my friend at the other end strikes out.
Thanks to Peter for the original pointer
Tiny brass spheres only 120 microns across form a variety of patterns when they are agitated in fluids trapped between glass slides. Rather than mechanically shaking the particles, the researchers applied an electric field to the slides, which caused the particles to bounce back and forth between the slides. The patterns that result resemble those formed in shaken containers of sand, ball bearings, and other large granular materials. In effect, the particles self-assemble in ways that may allow us to create novel and useful nanoscale structures for tiny electrical or mechanical components.
Walloon is the name given to the French speaking people of Belgium. Welsh is the English word for the original Celtic inhabitants of Britain. Both words have a common origin in the Germanic word walah which simply means foreigner and was bestowed upon these Romanised Celtic peoples by invading Germanic tribes (i.e. Saxons, Angles, Dutch etc)1.
A similar Slavic word wallach has been used to refer to the descendents of the Latin-speakers of Rumania but as the following text demonstrates, the same word has been used in its various forms for centuries to label the Other in many places right across Europe.
vlach, bloch, wallach, et alThat onomatapoeic Greek word meaning "the bleating of sheep" reminds me of another famous Greek coinage: "barbarian" or hoi barbaroi - speakers of "bar bar"-sounding languages.
A few years ago, while visiting Israel, I took the opportunity to visit the /Dorot'/ (`generations') computerized genealogical database at /Beth ha-T(e)futsoth/, the (impressive!) Museum of the Diaspora, located on the campus of Tel Aviv University; I sus- pected that our patronymic might be of Jewish derivation. There I discovered that Bloch (as well as Wallach, /etc./) is derived from the Slavic /vlach/, meaning not only `foreigner', but specifically "an alien speaking a Latin- related language"; it seems to be cognate to the Greek /blhxh/, meaning `the bleating of sheep' (obviously designating a meaningless and despised sound), as is the Germanic /Welsch/ for `foreigner (specifically Celtic, Welsh or Italian)'. The Old High German /Walah/ also meant `speaker of a Romance language'; late Gk. /blaxos/ referred to a Wallachian; Anglo-Saxon /wealh/ seems to mean `Celtic, foreign or strange'; and even Latin /Volcae/ referred to a Celtic tribe.
For example, in Bohemia the term /vlach/ was applied to the Italian silver- and gold-smiths whom Emperor Charles imported when those ores were mined in the Crown Lands, for the purpose of establishing coin-minting operations.
A Bulgarian post-doc in my department told me that till today a tribe (?) of Romanian-speaking folk along the border between those countries (Wallachia) is referred to as /vlachii/.
Currently the family name Vlach is used by families of Slavic extraction, apparently with no hint of Jewish lineage; there was also once a letter to the editor of TIME Magazine signed Vlachopoulos. Bloch, on the other hand, seems to be used exclusively by families which were at one time Jewish; this usage implies an attribution by Slavic residents to immigrants into Central Europe from further west (and south), presumably speaking Italian, French and/or Spanish, and conceivably at the time of the Spanish Inquisition and Expulsion of the Jews, commencing in 1492 (although that linkage will probably never be traced in full detail). Bloch families are found in Poland, Latvia, Russia and Germany as well as the Czech Republic; some even seem to have bounced back westward, after having acquired the label, and settled in France and Holland.
Mitachondrial DNA analysis has demonstrated that all human beings living around the world are related to a single group of humans that emerged in the Rift Valley around 100,000 - 130,000 years ago. Based on the fossil record in Africa it is thought that around 50,000 years ago there was a transition (perhaps the acquisition of language?) and with that anatomically modern humans suddenly started migrating out of Africa and colonizing the rest of the world. One of the earliest routes was along the coast of South Asia in boats. Moving at a reasonably swift one mile a year, in less than 10,000 years they had reached the Australian continent.
The accurate dating of this event is important not only for the history of Australia's indigenous population (whose struggle for the recognition of their traditional land rights and native title was given a considerable shot in the arm with the realisation of how long they had been in possession of Australia) but also because this date is an important one for piecing together the entire migratory history of humanity. For example, it is used for calibrating the rate of genetic mutation of human populations. In a technique known as genetic chronology the rate of mutation is then used to estimate when two human population groups diverged and how long ago was their last common ancestor.
In 1999, a research team led by Alan Thorne of the Australian National University threw a spanner in the works of this timeline by publishing a study in Nature which claimed that the age of "Mungo Man", the oldest skeleton found in Australia was at least 62,000 years old and perhaps even older. Thorne is a critic of the so-called "out of Africa" theory of human migration and proposes an alternative theory that humans did not leave Africa in a single wave at all but that modern humans are descended from several strands of hominids which left Africa at different times and which only later evolved in modern humans. His "multi-regional" theory requires a relaxing of the definitions of what constitutes "human" and posits that interbreeding must have occurred between the various contemporary types of homo sapiens, even with the Neanderthals. Thorne later went on to publish a study that claimed Mungo Man's mitochondrial DNA also differed from that of modern humans challenging the "out of Africa" theory even further. While this second study has been greeted with some skepticism because of the difficulties of extracting DNA from such ancient bones, Thorne's early dating of Mungo Man has been generally accepted as being problematic for the dominant theory.
Australia's oldest human remains: age of the Lake Mungo 3 skeletonOne of the big problems in this area is that dating is very difficult for objects that are this old. Carbon-14 analysis which works so well for dating organic material stops being reliable after about 30,000 years (while it can theoretically be used for up to 60,000 years, the chances of contamination from other sources becomes too high). Thorne's study instead used uranium series analysis in conjunction with electron spin resonance analysis of the tooth enamel and optically stimulated luminescence analysis of the sand found at the site.
Alan Thorne, Rainer Grün, Graham Mortimer, Nigel A. Spooner, John J. Simpson, Malcolm McCulloch, Lois Taylor, Darren Curnoe
Journal of Human Evolution, v 36, n 6, June, 1999, p591-612
We have carried out a comprehensive ESR and U-series dating study on the Lake Mungo 3 (LM3) human skeleton. The isotopic Th/U and Pa/U ratios indicate that some minor uranium mobilization may have occurred in the past. Taking such effects into account, the best age estimate for the human skeleton is obtained through the combination of U-series and ESR analyses yielding 62,000±6000 years. This age is in close agreement with OSL age estimates on the sediment into which the skeleton was buried of 61,000±2000 years. Furthermore, we obtained a U-series age of 81,000±21,000 years for the calcitic matrix that was precipitated on the bones after burial. All age results are considerably older than the previously assumed age of LM3 and demonstrate the necessity for directly dating hominid remains. We conclude that the Lake Mungo 3 burial documents the earliest known human presence on the Australian continent. The age implies that people who were skeletally within the range of the present Australian indigenous population colonized the continent during or before oxygen isotope stage 4 (57,000-71,000 years)
Luminescence & Radiometric DatingNow a new study from Melbourne University challenges the Thorne group's findings. By performing thermo-luminescence analysis on sand samples taken from the site they conclude that Mungo Man is not older than 40,000 years and that humans settled in Australia no earlier than 50,000 years ago. No doubt this news was received enthusiastically by most scholars in the field but it also seems likely that the controversy is far from ended.
Luminescence is a phenomenon exhibited by many crystals, such as diamond, quartz, feldspars and calcite. Energy absorbed from ionizing radiation (alpha, beta, gamma, cosmic rays) frees electrons to move through the crystal lattice and some are trapped at imperfections in the lattice. Subsequent heating of the crystal, or stimulation by absorption of light can release some of these trapped electrons with an associated emission of light - thermoluminescence (TL) or optically stimulated luminescence (OSL) respectively
The idea here is that all materials carry extremely low concentrations of radiogenic isotopes, line Uranium, which in turn expose the material to extremely low doses of radiation over a long time. That radiation frees electrons that get trapped in crystal defects, just like dosimetry badges. The total population of trapped electrons in turn determines the total dose. If you know the average dose per unit time, by studying the geology of the site, you can then use the ratio of total dose over average dose, and get the time period.
Sunlight on a crystal will evict the trapped electrons much faster than background radiation puts them in. So once the crystal is buried, the "clock" starts. Dig up the crystal, measure its luminescence (either optically or thermally stimulated), and you know the total dose. Compare with the average dose per unit time, and you know how long the crystal has been buried. This is a favorite means for dating buried sediments that are often rich in quartz and feldspar. For other materials, notably non translucent material, electrons become trapped in defects where the lattice potential is too deep and the electrons cannot be stimulated to come out. In those cases, electron spin resonance (ESR), which is much more complicated that luminescence techniques, can be used to count the number of trapped electrons by using a combination of microwaves and a variable magnetic field. The disadvantage of ESR is that it is much more complicated, and has larger uncertainties than luminescence techniques. The advantage of ESR is that, unlike luminescence, the electrons are not evicted from their traps, so the measurement can be repeated as desired on the same sample.
One of the key tests of reliability for any dating technique is the ability to intercompare with other techniques; they should all give the same age for the same sample, within the bounds of the usual experimental uncertainties.
Dawn in our Garden of EdenFurther reading:
Fifty thousand years ago, a lush landscape greeted the first Australians making their way towards the south-east of the continent. Temperatures were cooler than now. Megafauna - giant prehistoric animals such as marsupial lions, goannas and the rhinoceros-sized diprotodon - were abundant. And the freshwater lakes of the Willandra district in western NSW were brimming with fish. But change was coming. By the time the people living at Lake Mungo ceremoniously buried two of their dead, 40,000 years ago, water levels had begun to drop.
A study of the sediments and graves at Lake Mungo, published this week in Nature, uncovers the muddy layers deposited as the lake began to dry up. Twenty thousand years ago Lake Mungo had become the dry dusty hole we know today, but 20,000 years before that it had been a refuge from the encroaching desert, the study shows. Families clustered around the lake left artefacts, 775 of which researchers used to determine that the number of people living there peaked between 43,000 and 44,000 years ago, with the first wanderers arriving between 46,000 and 50,000 years ago.
This treasure-trove of history was found by the University of Melbourne geologist Professor Jim Bowler in 1969. He was searching for ancient lakes and came across the charred remains of Mungo Lady, who had been cremated. In 1974, he found a second complete skeleton, Mungo Man, buried 300 metres away.
The comprehensive study of 25 different sediment layers at Mungo - a collaboration between four universities, the CSIRO, and NSW National Parks and Wildlife and led by Bowler - concludes that both graves are 40,000 years old.
This is much younger than the 62,000 years Mungo Man was attributed with in 1999 by a team led by Professor Alan Thorne, of the Australian National University. Because Thorne is the country's leading opponent of the Out of Africa theory - that modern humans evolved in Africa about 100,000 years ago and then spread around the globe - the revision of Mungo Man's age has refocused
attention on academic disputes about mankind's origins.
Dr Tim Flannery, a proponent of the controversial theory that Australia's megafauna was wiped out 46,000 years ago in a "blitzkrieg" of hunting by the arriving people, also claims the new Mungo dates support this view.
For Bowler, however, these debates are irritating speculative distractions from the study's main findings. At 40,000 years old, Mungo Man and Mungo Lady remain Australia's oldest human burials and the earliest evidence on Earth of cultural sophistication, he says. Modern humans had not even reached North America by this time. In Europe, they were just starting to live alongside the Neanderthals.
"At Lake Mungo we have a cameo of people reacting to environmental change. It is one of the great stories of the peoples of the world."
THE modern day story of the science of Mungo also has its fair share of rivalry. In its 1999 study, Thorne's team used three techniques to date Mungo Man at 62,000 years old, and it stands by its figure. It dated bone, teeth enamel and some sand.
Bowler has strongly challenged the results ever since. Dating human bones is "notoriously unreliable", he says. As well, the sand sample Thorne's group dated was taken hundreds of metres from the burial site. "You don't have to be a gravedigger ... to realise the age of the sand is not the same as the age of the grave," says Bowler. He says his team's results are based on careful geological field work that was crosschecked between four laboratories, while Thorne's team was "locked in a laboratory in Canberra and virtually misinterpreted the field evidence".
Thorne counters that Bowler's team used one dating technique, while his used three. Best practice is to have at least two methods produce the same result. A Thorne team member, Professor Rainer Grun, says the fact that the latest results were consistent between laboratories doesn't mean they are absolutely correct. "We now have two data sets that are contradictory. I do not have a plausible explanation."