Letter: Ferry trials
My attention has been drawn to the interesting article ‘The risks of
ferry travel’ (18 August). I would like the opportunity to set the record
straight on a couple of points.
The SOLAS regulations and our own national requirements provide for
complete abandonment of passenger ships (including ferries) within a period
of 30 minutes from the time the signal to abandon ship is given. This is
not a ‘theoretical concept’. Trials are carried out on all British ships
utilising the different types of survival systems fitted to determine that
this requirement can be met. The recent test in the Mersey estuary referred
to in the article was not carried out for the Consumers’ Association; it
was, in fact, an exercise organised by HM Coastguard.
One of the objectives of the exercise was to test the evacuation procedures
using volunteer passengers and the ferry’s crew. Evacuation was successfully
achieved within the prescribed limits. The total exercise, which included
the inspection of the various stages of evacuation by independent observers
and the testing of the emergency procedures, communications and liaison
between the participating authorities extended over two hours but this is
not a reflection of the actual evacuation time.
D C S Thompson Principal Nautical Surveyor Department of Transport London
Letter: Here's to Japan
Comment touched on a recurring theme: ‘Japan is not doing enough basic
science and makes unfair use of foreign research’ (15 September). The charge
should be reversed: ‘We applaud Japan for putting to good use hard-won basic
research which would otherwise be wasted. It would be irresponsible for
the Japanese to direct their resources from applied science, product-development
and efficient production while the rest of the world so blatantly neglects
those activities.’
J R Tippetts University of Sheffield
Letter: Ion brew
Ariadne, whose weekly montage of quizzical gleanings affords me much
joy, has drawn attention to the unfamiliar word ‘hormesis’, tagged to the
dubious hypothesis that a little bit of ionising radiation is good for us
(1 September). Hormesis seems to be a new word, but the notion is not. I
am old enough to remember, from the 1920s, a sales pitch on bottled spa
water labels: ‘contains radium’.
R H Fowler Ashburton Victoria, Australia
Letter: Windbreaker
I fear that Wolf Seufert has rather missed the point. I did not say
that the various wings could not fly, only that Bernoulli could not explain
it (Letters, 8 September). Briefly, the Bernoulli argument is fallacious
because it is a circular one. In particular, the idea that the air has to
stream faster over the upper wing surface is itself a Bernoullian deduction
and is not supported by experiment.
Nevertheless I tried Seufert’s alternative experiment of contacting
some flying schools. One referred me to ‘any elementary textbook’. Another
referred me to Techniquest, Cardiff’s permanent hands-on science exhibition
which uses the Bernoulli argument as part of its advertising blurb.
Perhaps I am being overly pedantic about the nefarious effect of persistent
textbook errors. After all, the word ‘aircraft’ was introduced into the
English language, and the first passenger-carrying aircraft was designed,
built, and piloted by Alfred William Lawson, who though that gravity was
a form of suction (the resultant internal pressure being relieved through
an anus at the South Pole).
David Fisher Cardiff
Letter: Fuelling demand
It would appear that Nigel Mortimer is continuing on his course of flawed
logic and subjective analysis in his dimissal of nuclear power as a contributor
to ameliorating global warming (Letters, 15 September).
He quoted the world’s practically useful resources of uranium at 5-10
million tonnes; in his evidence to the Hinkley Inquiry he actually uses
the figure of 6 million. As any mining company will tell him, known mineral
reserves are dictated by demand and new discoveries generally follow growth
in demand. We have had, for example, around a 30-year reserve of oil for
at least the last 30 years. Currently, the uranium reserve to demand ratio
is about 150 years.
Even if Mortimer’s assertions on the limited availability of high-grade
uranium ores were correct, there is an adequate supply to meet half of the
world’s growing electricity demand for the next 70 years or so used in current
designs of nuclear power stations. Used in the fast breeder reactor, which
could be available as a commercial plant within two decades, this limited
resource could supply the world’s electricity demand for centuries. He dismisses
this option on the grounds that his evidence apparently overlooks the large
amounts that will become avalable from an expanding thermal nuclear power
programme.
Perhaps a more telling point is that the concerns expressed by Mortimer
did not appear to weigh heavily in the conclusions of the Intergovernmental
Panel on Climate Change when they identified nuclear power as a long-term
contributor to global warming amelioration.
D M Donaldson AEA Technology London
Letter: Global problems must of necessity have global solutions?
Nigel Mortimer seems to be under the misapprehension that global problems
must of necessity have global solutions. If this were the case, then his
test of practicality for solutions to the problem of global warming would
rule out not only nuclear power but also improvements in energy efficiency
and conservation and more extensive exploitation of renewable sources. The
social, environmental, technological and economic practicalities of world
energy supply dictate that we shall need all of these and a substantial
contribution from coal, oil and gas if we are to have a realistic chance
of meeting the energy needs of the next century without curtailing the expanding
living standards of the developing world.
Conservation and improved energy efficiency will have to play a key
role but they are principally options for us, the privileged inhabitants
of the north. They are unlikely to be realistic options for India or China
or the other nations who are struggling to improve their people’s health
and living conditions.
Inevitably, the countries of the south will increase their rate of coal
burning to meet their needs. Nuclear power offers the countries of the north
the only practical possibility for substantially offsetting the resulting
increase in the rate of carbon dioxide emissions. The extent to which this
opportunity could be exploited depends partly on economics and partly on
availability of high grade uranium ore. We concluded that a world nuclear
programme of at least 1000 gigawatts, but probably no greater than 2000
gigaqatts, would be feasible by 2025.
J K Wright, R S Rodliffe Nuclear Electric plc Bristol, Avon
Letter: Animal wrongs
D Jack’s analysis of Peter Singer’s book Animal Liberation is too inaccurate
to pass unchallenged (Letters, 1 September). Singer himself later apologised
for using the term ‘animal liberation’, and it is not used in the book with
that title. Tom Regan has a better claim to being the philosopher of animal
rights. Neither of them have encouraged the use of violence against individuals
or sabotage in their writings. If philosophical justification was necessary
to engage in violent activities the world would be a much less violent place
than it is today.
Neither Singer nor Regan consider that animals have ‘essentially equivalent
rights to those of human beings’. They argue that for those characteristics
common to humans and (some) other animals, all animals with the same characteristics
should receive equal consideration of this aspect only.
For instance, as all vertebrates have a similar pain perception system,
the pain of a rabbit should (in itself) be considered as important as the
pain of a human. Other things may also be important (the rabbit does not
know that the pain will not kill it, a social vertebrate’s pain will affect
its fellows, and so on).
Nobody is claiming that the rabbit has human-style rights to freedom
of expression, or education.
L C Gamsa-Jackson Chelmsford Essex
Letter: Dinosaur donor
Such an important and exciting project as the forthcoming Dinosaur Gallery
at the Natural History Museum will obviously arouse a great deal of public
interest. May I therefore state that there is no dilemma over the funding
of this gallery, and that when the gallery opens in Spring 1992 it will
be the finest of its kind in the world, bringing to life the history of
the dinosaurs through newly displayed fossils and models (Feedback, 15 September).
Current discussions with Customs and Excise do not in any way affect
the progress of the gallery, or The Ronson Foundation Pledge, which has
already donated the second of its five gifts of 100,000 Pounds towards this
permanent display.
The example taken of the Natural History Museum does, however, raise
a much larger question which could affect other charities and scientific
institutions. This concerns the possible imposition of a VAT ruling on charitable
sponsorship. The implication of this ruling, if it were to be enforced,
would be to tax charities and to impose a huge drain on resources for the
sector as a whole. A tremendous number of charitable appeals would be significantly
affected, particularly those involved in the construction of new buildings
or in scholarships, were these to carry the name of the donor.
Neil Chalmers, Director Natural History Museum London
Letter: Gas station
I do not want to intervene in the argument between British Gas and Earth
Resources Research about the amount of methane which leaks from BG’s pipes
(This Week, 22 September). It seems worth asking, however, whether the figures
for existing leakage rates are relevant to the proposal that the contribution
of fuel use to the greenhouse effect can be reduced by switching from coal
and oil to gas.
It is far from being a universal truth that energy taxes within the
European Community encourage the use of coal and oil rather than gas. It
is not true in Britain, and the reverse situation exists in Denmark. On
the other hand, there is an EC directive which aims to prevent the burning
of gas in power stations. This is the obvious area in which its use could
be increased. I suggest that leakage associated with this would be much
lower than average for the system as a whole simply because large leaks
are more likely to manifest themselves, explosively or otherwise, than numerous
small leaks from the low-pressure distribution system.
John Feather London
Letter: Artistic set
Benoit Mandelbrot’s article (‘Fractals – a geometry of nature’, 15 September)
reminded me of my first sight of one of his sets. It reminded me irresistably
of something, but I could not think what. Recently, the penny dropped. Aubrey
Beardsley. Beardsley’s illustration to Pope’s Rape of the Lock (1896) shows
his anticipation of self-similarity with scale change: a nice anticipation
of science and art.
William Paton Oxford
Letter: The Sierpinski Trangle
Benoit Mandelbrot’s article is the most recent of many I have seen on
fractals showing the generation of the Sierpinski triangle without mentioning
its remarkable isomorphism with that of Pascal. It must have been many years
ago that I saw an illustration of Pascal’s triangle in which the odd numbers
were coloured blue and the even red. The picture of the Sierpinski triangle
brought it back through the mists of time.
The nth generation of the Sierpinski triangle is precisely the Pascal
triangle with 2n rows, in which odd numbers are represented by black triangles,
while the evens are represented by the virtual upright white triangles in
the white space. The isomorphism derives from the rule of formation of Pascal’s
triangle, which converted to odd and even says that each triangle on a lower
line is white or black according to whether the two triangles immediately
above it are of similar or opposite colours.
Stan Armstrong Malvern Worcestershire
Letter: Nitrate readings
Mike Saull’s Inside Science supplement demonstrates a poor understanding
of the issues, and contradicts the conclusions of the authors recommended
in ‘further reading’ (‘Nitrates in soil and water’, 15 September). He would
not have concluded that there is ‘no evidence that fertilisers directly
affect the amount of nitrate in water’, had he read ‘Laying the ground rules
for nitrates’ (New 杏吧原创, 29 April, 1989).
I am most concerned when the author considers what lies behind the ‘wholesome
image of organic farming’. He shows a complete ignorance of standards as
well as the practices and objectives of organic farmers. He is also unaware
of the results of research.
Organic farmers use rotations which balance the fertility building pasture
phase (including clover) with the exploitative arable phase. Consequently,
the average leaching rate of nitrate is actually very low, the higher levels
occurring in the first winter after pasture cultivation being balanced by
the very low losses under pasture. Our research is directed towards quantifying
and minimising this risk. Data show a mean leaching rate of 20 kilograms
of nitrate per hectare from an organic rotation. Further organic farmers
do not spread and plough-in manure on arable land in the autumn.
Christopher Stopes Elm Farm Research Centre Newbury, Berkshire