Letters: Just plane weird
I am hoping that some reader can help explain to me the mechanism behind
a rather strange phenomenon I have occasionally observed at Los Angeles
airport.
A friend and I would go to the airport to watch the planes come in,
stopping on Sepulveda Boulevard, which is just at the edge of the airport
and runs right underneath the flight path of most landing planes.
While the huge planes were impressive enough, our attention was captured
by an event that sometimes occurred between twenty and thirty seconds after
a plane had flown over: a thin tube of misty air would zap past us at apparently
high speed accompanied by a rather loud flapping sound. Sometimes the ‘mist’
would follow a straight path, but often it would follow a really contorted
path that made the ‘mist’ look like a snake engaged in a violent path –
rather captivating to watch.
We suspected that the effect was some sort of remnant of the vapour
trails that sometimes came off the tips of the wings and tried to confirm
this by direct observation, but we could never keep track of such a trail
for more than 5 seconds. Also, we were never totally convinced that the
two effects were correlated. Anyway, wouldn’t such a trail dissipate within
a few seconds?
Timothy Surendonk Auckland, New Zealand
Letters: No problem
T. Roche writes about the service volunteer programme at the Chemical
and Biological Defence Establishment, Porton Down (Letters, 12 February).
This began in the 1920s and has involved some tens of thousands of servicemen.
These human studies are carried out in such a way as to ensure that there
is no harm to the members of the armed forces.
Each volunteer on arrival at CBDE Porton Down is given a thorough
medical examination and is only allowed to take part in a study if judged
to be medically fit and not suffering from any condition that might prejudice
the results of the study. The study is explained carefully to the volunteer
who is advised that he or she may withdraw without any explanation at any
stage during the study and without any detriment, penalty or pressure.
The explanation about the study is given by those conducting the study
and by a military officer in a lay statement, in words that the volunteers
will understand. At the end of the study, each volunteer is again medically
examined and the fact that the person has been a volunteer at CBDE Porton
Down is entered on the individual’s medical records.
Such human studies are only carried out when there is a clear military
need. Studies fall into three categories: assessment of the ability of service
personnel to operate new equipment and procedures; evaluation of the military
acceptability of proposed new drugs to ensure that there are no undesirable
side effects; studies of the effects of very low and medically safe concentrations
of chemical agents on unprotected personnel.
The standards adopted for these volunteer studies are in line with
those for use of healthy civilian volunteers elsewhere in Britain and are
in accordance with the guidelines published by the Royal College of Physicians.
All proposals for human studies are evaluated by an independent ethics committee.
Recently, the practice has been instituted in which the lay statement
read to all volunteers by a military officer states that: ‘It is CBDE policy
to call back some volunteer subjects for re-testing from time to time to
ensure that techniques used give consistent and reproducible results and
that no changes in the way we have applied the tests have occurred with
time.’ From time to time, service volunteers have been recalled so that
checks on their medical health can be made. There is no particular frequency
or pattern to such recalls.
Over the past 30 years, there has been no evidence available to the
Ministry of Defence to suggest that service volunteers who have participated
in human studies at the CBDE have suffered any long-term harmful effect.
Insofar as service volunteers who at some later date fall ill are concerned,
the MOD will make available their medical details to their doctor on request.
Graham Pearson Ministry of Defence Chemical and Biological Defence
Establishment Porton Down, Salisbury, Wiltshire
Letters: Coming and going
Once again it seems that the Science and Engineering Policy Studies
Unit (SEPSU) statistical survey on the brain drain has served only to muddy
the waters.
Andy Coghlan concludes that ‘Roughly equal numbers of researchers left
the country and arrived between 1984 and 1992′ (This Week, 20 November
1993), Jon Turney claims that ‘The latest results . . . appear to indicate
a net inflow’ (Forum, 11 December 1993) and William Waldegrave draws comfort
from his view that ‘The study shows that the UK is benefiting from a two-way
flow of high-quality scientists and engineers’ (This Week, 20 November 1993).
I have just received my own copy of the 1993 report, however, and
the figures tell me a somewhat different story:
a) Britons entering: 144 b) Foreigners entering: 318 c) Britons leaving:
447 d) Foreigners leaving: ?
Yes, that’s right, the 75-page report remains silent on the number of
foreign scientists leaving Britain, without which any conclusion about
a ‘net inflow’ is a complete non sequitur.
Exactly the same omission appeared in the 1987 SEPSU survey, allowing
similar conclusions to be drawn: ‘The data show that there is a net inflow
to Britain, from, for example, India and the Middle East’ (Alan Smithers,
Letters, 25 January 1992); ‘. . . a general survey in 1987 found almost
as many researchers arriving in Britain as leaving’ (Forum, 11 December
1993).
I can well understand why government ministers might wish to be economical
with the truth by adding (a) to (b) and subtracting only (c), but it beats
me why British scientists should want to go along with the deception.
Michael Duff Texas A&M University College Station Texas
Letters: Concrete advice
While the theme of your article ‘Concrete claim for conservation’ (Technology,
30 October) is entirely praiseworthy and effective, may I draw your attention
to an innovative invention which takes a different approach to the mixing
of materials by nonmechanical means?
The method of using compressed air to create turbulence in a tube while
the medium is falling by gravity has a number of advantages: it permits
the ingredients to be transported dry to a site, does not require a purpose-built
cement mixer lorry, and is totally self-cleaning. So it can be seen to be
even more environmental-friendly than the method suggested in your article.
D. G. Ellan Whitehaven, Cumbria
Letters: Global holidays
In ‘If it’s warm it must be a workday’ (This Week, 29 January) I noticed
with some amusement that ‘at least 2 per cent of Thursdays are Thanksgiving
holidays in the US’. Strange, for a one-day-a-year holiday . . .
Nevertheless, this concept may offer hope for a pleasant battle against
global warming. There has been a trend (in this light, a very healthy one)
toward an ever-greater number of national holidays in the US, at least,
particularly honouring ethnic minorities (Martin Luther King Day and Kwaansa
come to mind). If each of these has a nearly 3 per cent input into this
cooling effect, not to mention the ancillary benefits of less pollution
and power use during these periods, perhaps Adrian Gordon has stumbled on
something really revolutionary. An answer to global warming may simply
be declaring holidays – lots of them.
John Townley Virginia, US
Letters: Eye exercises
Alison Brooks left us in suspense at the end of her interesting article
on myopia (Forum, 5 February). I bought The Art of Seeing (Aldous Huxley)
and a lighter interpretation, Better Eyesight Without Glasses (Harry Benjamin),
in the early 1940s. The former book referred to a system of remedial exercises
due to William Bates, which was featured in the Daily Mail of 26 October
1993. Practitioners of this system can be contacted through The Bates Association
of Great Britain, 11 Tarmount Lane, Shoreham-By-Sea, West Sussex BN43 6RQ.
Incidentally, Brooks seems unkind to optometrists in general. Their
speciality, as I understood it, is the sight-testing aspects of diagnosis
of ophthalmic disorders and not so much the justification of the regular
upgrading of our spectacle lenses.
Peter Sculpher London
Letters: Self-dialogue
John McCrone (‘Inner voices, distant memories’, 29 January) tells how
a child, in acquiring its inner voice, talks aloud to itself – that is,
practises Lev Vygotsky’s ‘self-addressed speech’. In the evolution of our
line, might not such speech have emerged long before our inner voice?
Might not self-addressed speech be both necessary and sufficient for
the first stirrings of abstract thought, memory and self-awareness? If Neanderthals
talked to themselves, might not this species bury its dead in a ceremony
employing language that gives names to whatever concepts, feelings and abstractions
it has created to accompany the solemnity?
Yet we can suppose, along with McCrone, that silent, inner speech is
what sets us apart from earlier species in our line. We can suppose that
the emergence of unvoiced self-dialogue accounts for the ‘astonishing suddenness’
of evidence of human culture in the archaeological record.
Our inner voice is the outer voice’s servant in a verbal exchange: each
speaker uses it to supply the last part of another’s sentence and to prepare,
even rehearse silently, the first part of a response. The inner voice permits
us to prepare an argument and persuade. It permits us to increase our repertoire
of expected outcomes. Words become matter for dreaming.
Acting through dream, the inner voice permits the creation of stories
or ethical principles and facilitates their retelling, word for word, generation
after generation. Language becomes more powerful for organising and transmitting
knowledge; for creating academies that indoctrinate novices and guard ‘truths’;
for promoting and elaborating play; for inventing a new pattern of behaviour
and endowing it with ‘this is what is right to do’; for creating history
and a future.
Arthur Squires Virginia Polytechnic Institute and State University Blacksburg,
Virginia
Letters: Maundering maths
I much appreciated John Gribbin’s article (New 杏吧原创, Science, 22
January) on the power of mathematics, and his kind references to a letter
and preprint of mine (in the latter, as a slight amendment, quark pair structures
are conventionally described as ‘mesons’).
On the larger questions he raises of the nature of reality and associated
issues of mathematical Platonism, it is perhaps unfortunate that the work
of the physicist and mathematician can generally proceed without regard
to these questions, with the consequence that these practitioners often
tend to view such considerations as irrelevant maunderings suitable only
for the studies of philosophers – who thus, almost by default, are left
to explore virtually alone these fascinating areas.
Bruno Augenstein Santa Monica, California
Letters: Not so super
May I comment on the article on Scottish superquarries (Focus, 8 January)?
There is a feeling among many people in Scotland who are interested
in the subject, that the time has come for a government inquiry into the
whole idea of superquarries.
Among the basic factors that need to be addressed are environmental
factors (including airborne and water-borne pollution) and the ‘jobs’ issue.
The number of local jobs created by a superquarry is small (around 100);
more and smaller quarries provide more local jobs.
The Highland economy is highly dependent on tourism and it is certain
that in at least some of the areas Wilson designates as potential quarry
sites, the siting of a superquarry would result in a decline in the local
economy, through loss of tourist-related jobs and income.
We should also consider how many jobs could be created by recycling
more demolition rubble – and how much less material would then need to be
transported.
Gay Anderson Onich, Fort William, Scotland
Letters: Sensible solstices
Charles Moore (Letters, 5 February) wishes to understand why the earliest
sunset and the latest sunrise do not coincide at the winter solstice.
The apparent motion of the Sun across the sky is actually a superposition
of two effects, the rotation of the Earth on its axis, and the orbital
motion of the Earth about the Sun. The Earth rotates on its axis at an
effectively uniform rate, but its movement round the Sun is more variable.
The Earth in its orbit does not keep a constant distance from the Sun,
and when it is nearer to the Sun it moves faster than when it is further
away, in accordance with the law of conservation of angular momentum. The
Sun does not therefore appear to move across the sky at a constant rate.
Our clocks, on the other hand, divide the passage of time into days,
hours and minutes of equal duration regardless of the speed of Phoebus’s
chariot. The result is that the clock and the sundial get ahead of each
other as the year progresses. The effect is most pronounced when the Earth
is closest to the Sun, which just happens to fall rather close to the Northern
winter solstice. In early December, the Sun is well ahead, and appears to
rise and set early; by late January, the clock is well ahead, and the Sun
appears to rise and set late.
Leslie Harris Cheltenham, Gloucester
Letters: Making a point
I am fascinated by ‘Headstone is no pushover for vandals’ (Technology,
19 February), in particular the use of a downward-pointing spike. Presumably
a slightly longer spike could be fitted for burials of people with a craving
for blood?
Rob White East Barnet, Hertfordshire
Letters: Own goals
Poor Peter Beardsley, hit by the curse of the cliche where he might
least expect it. Genius he may be. But ‘a wayward genius’? Never.
Tim Lincoln Redhill, Surrey
Letters: Own goals
Re your Comment on risk-taking and football (5 February): how can
you call a defender who regularly scores (the other day with a header from
outside the box!) ‘safe and steady’? Rather than axing Carlton Palmer, Terry
Venables should be signing another Sheffield Wednesday player – Chris Waddle.
Perhaps in future you should make your comment on subjects you know something
about, rather than football. PS I notice that your Australian advertising
rep. is Ian Wright. You’re not a bunch of Arsenal fans are you?
Ian Rogers Sherwood, Nottinghamshire
Letters: Sensible solstices
There are other noticeable aspects related to this phenomenon. After
Christmas, the evenings pull out very quickly, but the dark mornings drag
on well into January. In the early autumn, the evenings suddenly pull in
with disturbing rapidity.
K. A. Harrison Royston, Hertfordshire
* * *
Note – there was an error in our published version of Charles Moore’s
letter, the second sentence of which should have read: ‘Sunrise is latest
about a week after the mean winter solstice, while sunset is earliest a
week before it . . .’ – Ed
Letters: Sensible solstices
If Moore throws away his watch and clocks and installs a sundial, he
will find that earliest and latest sunrises and sunsets do occur at the
solstices.
Alan Lane West Ewell, Surrey
Letters: Sensible solstices
If Moore made another observation, he would discover a further irregularity.
He would discover that the Sun is rarely at its zenith at 12 o’clock (allowing
for British Summer Time, of course).
Chris Randall Swindon, Wiltshire
Letters: Sensible solstices
Midday Greenwich Mean Time is not the time when the real Sun reaches
its highest point during the day at Greenwich – it is the time when the
mean Sun reaches its highest point.
The mean Sun is a fictitious sun which, during the course of the year,
moves around the celestial equator (a great circle on the sky projected
from the Earth’s equator), rather than the ecliptic like the real Sun. It
is defined to have perfectly uniform motion so as to allow clocks to run
smoothly.
In contrast, clocks running according to the real Sun would have to
continuously vary their ticking rate during the course of the year due to
the varying angular speed of the Earth in its elliptical orbit around the
Sun and the varying angular distance of the Sun from the celestial equator.
If the times of sunrise and sunset (of the real Sun) are measured on
a time-scale in which midday is taken as the time when the real, rather
than the mean, Sun reaches its highest point, the paradox does not arise.
Alan Harris Institute for Planetary Exploration Berlin