Letters: Busting ghosts
One way in which the ghosts could be exorcised from London’s TV would
be to stop transmitting from Crystal Palace and transmit instead from the
top of the Canary Wharf Tower.
This would give a more even distribution of signal in the London area
and also provide a much-needed raison d’etre for the tower.
F. G. Johnson Lymington, Hants
Letters: Whalers lose
By Bravo, Jeremy Cherfas, for being the first journalist to get the
new quota-setting rules of the International Whaling Commission about right.
But whoever wrote the title of his article (‘Whalers win the numbers game’,
11 July) managed to miss the point entirely. It is the ex-whaling and non-whaling
countries in the IWC that, if any, have ‘won’ the game. The new rules take
the existing uncertainty about the biology of baleen whales sufficiently
well into account to allow the catch limits set under them, when not zero,
to be so small by the whalers’ standards that the North Atlantic whalers
hate them. That’s why Iceland left, and Norway is now cocking a snook at,
the IWC.
Norway fought for years against having any new rules, having done nicely,
thank you, under the old ones. Iceland decided to leave as soon as the
IWC agreed last year, in principle, to Justin Cooke’s algorithm. The governments
of both countries were upset that the majority of countries adopted the
rules; their hope was that the majority would find an excuse to reject them
and so expose themselves to the renewed accusation that non- and ex-whalers
were procrastinating.
Cherfas quotes Icelandic scientist Johann Sigurjonsson as saying, with
respect to the commercial whaling moratorium, ‘Iceland manages cod, all
the time revising the management procedure, but we don’t stop catching cod
while we are revising.’ The day I read that I also read, in fishing industry
magazines, that cod fishing in the western North Atlantic has been stopped
completely for 18 months, because of management errors, and for the same
reason Iceland has had to cut dramatically its own cod catches. A difference
is, of course, that fish populations such as cod can recover substantially
in a couple of years, while whales need several decades.
The fact is that the commercial whaling moratorium has provided the
conditions under which it was feasible for a few scientists to put all their
energy into trying to devise fail-safe management rules. The present continuation
of it likewise can in theory provide the conditions for negotiating, for
the first time in whaling history, effective international arrangements
for monitoring and enforcing the implementation of the new rules. Unfortunately
the Norwegian authorities, in particular, are as anxious to avoid successful
negotiations of that kind as they have been to avoid agreement on safe quota-setting
rules.
Sidney Holt Citta della Pieve, Italy
Letters: Cannibal quarrel
The debate on cannibalism generated by Paul Bahn, Bill Arens and Michael
Pickering is relevant not only to our perception of our ancestors, but
also to the relationship between indigenous peoples and colonisers.
The Aborigines of Australia were deemed to be cannibals before the First
Fleet arrived. That perception justified the process and brutality of colonisation:
for ‘they are cannibals’ read ‘we want their land’.
Fear and fertile imaginations then coloured observations (for example,
of burial rituals), leading to the exaggeration, distortion and fabrication
of evidence; turning suspicions and allegations into assertions.
One derivative popular on the Palmer River goldfields in the 1870s
asserted a preference for the flesh of Chinese over that of Europeans.
Miners used it to deter competition from going onto the goldfields.
The handful of anecdotal supporting accounts, which became more gory
and implausible with repetition, have been exposed as fabrications. There
is not a single credible account of a person of either race ever having
been eaten by Aborigines.
The myth persists, resistant to challenge. It offends and hurts Aboriginal
people; it underpins white attitudes of hostility, rejection and superiority.
This correspondence is now closed – Ed
Richard Buchhorn Brisbane, Australia
Letters: Cannibal quarrel
In your letters column of 20 June, Tim White responded to Paul Bahn’s
review of White’s book Prehistoric Cannibalism (11 April). Bahn argued that
mortuary ritual, rather than cannibalism, was a more likely explanation
for the damage or destruction of some prehistoric human remains. In his
review Bahn made reference to my article ‘Food for Thought: An Alternative
to Cannibalism in the Neolithic’ (Australian Archaeology 28: pp 35-39).
White defended his position through a criticism of my paper. He accused
Bahn of ‘outrageous assault’ on his scholarship and ‘egregious mischaracterisation’
of his work. I am afraid I must now level the same charges against White
on the basis of his letter.
In my article I did not dismiss cannibalism as a possible explanation
for damage to skeletal material. Rather I argued that available quality
ethnographic evidence supported mortuary practices as providing an alternative,
more testable, and more realistic explanation for deliberate damage or destruction
of human remains.
White intimates that my evidence was limited and relied largely on a
single historical account. In so doing he ignored other references, in
both the article and in my thesis, and my own observations. White makes
reference to a particular film as being the reliable evidence of mortuary
ritual related to destruction of bones. This is true. The film is, however,
representative of a well-documented mortuary ceremony once common in northern
Australia. The quality of the film supports my arguments that many early
observers failed to stay for the non-cannibal culmination of funerary proceedings,
preferring instead to leave and let their preconceptions fill in the missing
pieces.
My research examined 440 supposed instances of Aboriginal cannibalism
from 298 reports. Of these, 125 (29 per cent) claimed first-hand experience.
Of these, only six, or less than 1 per cent, were objectively irrefutable.
In other words, valid alternative explanations existed for 99 per cent of
reports claiming cannibalism, with mortuary rites being the most likely
explanation. Why then shouldn’t a similar percentage loading be applied
to the interpretation of archaeological remains?
The question that still remains unanswered is, given that the quality
material and documentary evidence for bone damage occurring during mortuary
rites is so great while similar evidence for such damage occurring during
cannibalism is so poor, why do some researchers insist on the ‘odd man out’
explanation?
Michael Pickering La Trobe University Victoria, Australia
Letters: School support
To Stephen Dibb’s suggestion about support subscriptions (Letters, 18
July), let me append another idea that I adopted years ago.
Just before each autumn term I remind the science department at our
local comprehensive that a year’s worth of New 杏吧原创 awaits collection,
and they go to supplement the miserably inadequate supply of books now provided
for schools.
I’m told that they are much appreciated.
John Brunner South Petherton, Somerset
Letters: Whalers lose
Your interesting editorial on whaling (Comment, 11 July) says, quite
rightly, that almost nobody was willing to take a moral stance on whaling
at the recent IWC meeting. But IWC itself has addressed the moral issue
of cruelty since the late 1970s. Indeed, the use of a specific method of
killing, the cold harpoon, was banned as cruel in 1982.
Over many years the Royal Society for the Prevention of Cruelty to Animals
has consistently said that whaling should not continue because of the inevitable
pain and suffering that is involved. No method of killing whales is humane.
And the moral argument is that if you cannot kill whales humanely then you
should not kill them at all.
T. Suckling RSPCA Horsham, West Sussex
Letters: Top quark
With regard to William Bown’s article on the so-called discovery of
a top quark (This Week, 27 June), when I spoke with him I did not claim
to have found the top quark. That is a job for an experimenter, whereas
I am a theoretical physicist. The ‘earlier paper’ he mentions gave a speculative
analysis of an event already published by the collider detector (CDF) group
at Fermilab, but there was no claim that this event was due to top-antitop
production and decay.
We were completely open and told Bown the current situation in this
research, and even sent him copies of our three papers on top-antitop event
analysis.
The CDF group at Fermilab is not blocking the publication of any paper
of ours. I should note here that we would never publish data from any group,
unless it has given us formal permission to do so or has already published
it itself. We have never done so in the past, and will not do so in the
future.
When Bown asked me what, supposing that a top quark were found now,
would be the effect on the Tevatron Main Injector project, I told him that
this upgrading programme would then have the highest priority, since the
Tevatron would be the only accelerator capable of top quark studies before
the next century. His statement in the last paragraph that money spent on
the Tevatron upgrade would be wasted is opposite to what I said.
Richard Dalitz Department of theoretical physics University of Oxford
Letters: Move the mountain
Re your issue of 18 July. It seems to me that moving the European sludge
mountain (page 11) to the Pacific island of Nauru (pages 12 and 13) might
solve two major environmental problems (provided the transporting tanker
does not break).
Marilyn Minchom Pinner, Middlesex
Letters: Physics flourishes
Contrary to Stephen Clackson’s assertions, (Forum, 4 July) the Physics
Unit at the University of Aberdeen is not closing at the end of this academic
year. It is true that the single Honours physics degree course will no longer
be available from 1992-93 because of the funding policies of the 1980s.
However, this year 575 students have been registered for a total of 15 courses
in physics at Aberdeen and these courses will continue to be run. A mathematics
with theoretical physics Honours degree is still taught and the university
is planning to develop in the near future combined Honours programmes with
physics as a key component.
There is a considerable amount of activity in physics in the university,
including that of the only 5-research rated biomedical physics and bioengineering
department in Britain. Funded research is also continuing in X-ray scattering,
upper-atmosphere physics and a range of areas in engineering physics and
material science, within the departments of engineering and chemistry. The
redevelopment of physics is being carefully plannned in ways which will
ensure its future as a core discipline in the University of Aberdeen.
Physics in Aberdeen is clearly not at an end.
J. M. Irvine University of Aderdeen
Letters: Water warrior
May I counter the suggestion made in your Comment of 20 June, that
Bukar Shaib, Chairman of the Federal Environmental Protection Agency, has
apparently no awareness that his government is ‘creating deserts’ in Northern
Nigeria.
Shaib is at the forefront of a wide-based initiative to rationalise
and plan the water resources of the Komadougou Yobe basin.
Shaib has twice spearheaded a deputation to the presidency of Nigeria
with specific recommendations that aim to achieve a sustainable-use scenario
for the large-scale irrigation schemes, the urban water supplies, and the
small-scale users of the wetlands.
Shaib and his associates in the Federal Environmental Protection Agency,
and other relevant federal ministries and agencies, are all presently striving
to apply these recommendations without completely dismantling the developments
made in the past 30 years, much of which were performed under ‘Western’
advice.
Henry Thompson Hadejia-Nguru Wetlands Conservation Project Kano, Nigeria
Letters: Comet concern
Inaccuracies abound in your Giotto article ‘Close encounters of the
comet kind’ (11 July).
A number of us in the Giotto Science Team did expect the comet probe
to survive the Halley encounter and we planned to continue our observations.
The spacecraft was of course protected against destruction by ‘a small grain
of dust’ impacting at 68.4 kilometres per second – protected by a special
dual shield of 1-millimetre aluminium, 25 centimetres ahead of a thick kevlar
plate.
The first sizeable impact of 20 miligrams, 15 seconds prior to closest
approach did not break the radio link ‘for about half an hour’. The actual
blackout, lasting only 22 seconds, was due to a pointing error, probably
resulting from an electrical discharge 8 seconds before closest approach.
The spacecraft wobble, caused by several impacts over 20 seconds, did
not stop radio transmissions. The magnitude of the wobble turned out to
be remarkably close to our prediction of 1 degree.
The best of the new data on comet Grigg-Skjellerup came from the magnetometer
and plasma detectors, not – as disparagingly written – to ‘fill gaps in
models of plasma physics’ but to model quite a different plasma regime where
the gyrations of the ions are large compared with the interaction region.
That situation is relevant to all comets as they weaken, and will help us
understand how these bodies are protected from the energetic solar wind.
The lack of a bow shock, yet the presence of highly energetic comet ions,
will throw light on a key mystery of astrophysics – the generation in interstellar
space of high energy particles, even cosmic rays.
Max Wallis University of Wales, Cardiff
Letters: Freezing faster
Cold water reaches maximum density at 4 掳C, and stratifies. It can
only lose heat by conduction internally, which is slow. Most of the heat
loss is from the top surface by evaporation and by air convection. Hot
water acquires vigorous internal convection currents during early cooling
and the momentum continues to bring water to the surface when cool, thus
preventing stratification. The hot water reaches 0 掳C throughout first,
and even then currents may persist allowing overall supercooling and increasing
the rate of conduction through the surface ice. The shape and material of
the container must not impede circulation or conduct too much heat.
Now, why are peas green? (What use is chlorophyll inside the pod?)
J. K. Wood Liverpool
Letters: Busting ghosts
Several years ago I was involved in a project aimed at measuring the
reflectivity of metallised glass. The problem was to safeguard the many
civil radar sites round Britain from encroachment by property development.
Increasing numbers of buildings were being designed then with metallised
glass.
Tests showed that a fine pattern of lines cutting the reflective film
on the glass into a series of disconnected islands would reduce the reflectivity
significantly. It should be possible to etch a broad band UHF pattern on
window films with a laser on site, so that incident signals reflect from
the glass 180 degrees out of phase with that reflected by the metal cladding
of the building. The two sets of waves will then cancel each other out.
Alternatively the engraved pattern could scatter the waves so that the building
no longer acts as a reflector.
Enterprising manufacturers of solar-protection glass could specify
the appropriate frequency bands to be ‘tuned out’ at the design stage of
large development.
J. V. Langley National Air Traffic Services London
Letters: Busting ghosts
Re the problem of television ‘ghosts’ caused by reflected signals from
Canary Wharf tower (Technology, 18 July). Until recently, most local television
programmes in New York City were transmitted from the Empire State Building,
and aside from problems caused by an overenthusiastic simian visitor (King
Kong), this system generally worked.
However, in the late 1960s construction began on the World Trade Center
towers, a twin set of 110-storey buildings, rectangularly shaped, and clad
in highly reflective metal. As they are located approximately 3 miles south
of the Empire State Building, a great deal of multi-path ghosting was expected,
and, in fact, occurred.
To ameliorate the problem, ‘translators’, or ‘repeaters’, were placed
in service to rebroadcast the affected signals on a different frequency,
and in a directional beam facing northwards. The people affected by ghosting
then had the option of switching to a second frequency, on a different channel,
which, being directional, did not bounce off the towers
Danny Burstein New York City, US
Letters: Freezing faster
Mark Channon (Letters, 25 July) asks why warm water freezes more quickly
than cold in a domestic fridge (and reports that it really does). Attempts
to repeat this experiment in laboratories usually show that the cold water
freezes faster. The difference? The surfaces of domestic fridges are usually
covered with a layer of frost. The warm water melts the frost, so that the
surrounding vessel makes better contact with the cold metal below. The
cold water remains partially insulated by the frost layer. (The same mechanism
explains why something very similar occurs for buckets of water left out
in the snow.) Mr Channon should thoroughly defrost his freezer compartment
and try again.
Ian Stewart University of Warwick
Letters: It really hurts
Andy Coghlan informs us that ‘mastitis brings discomfort and fever’
(This Week, 11 July).
I had mastitis when I was breastfeeding, and I can vouch for the fever.
As for the physical sensation, I invite male readers to imagine that their
testicles are inflamed, twice the normal size, hot, and being pressed on
all sides by the tight skin of the scrotum. This I would guess to be about
the equivalent of what females feel when they have mastitis. ‘Discomfort’
my foot.
I feel it is important to make this point because it would seem that
unfortunate cows with mastitis are not let off the machine milking routine.
What must it be like to be subjected to such handling in that state? I understand
that mastitis often gains entry to the udder in the first place via bruising
and damage caused by careless and rough fitting and removal of mechanical
milkers. What must it be like to have metal teats roughly fitted and removed
when the udder is already inflamed with mastitis? There’s a lot of suffering
going on on our farms, and as a first step towards doing something about
it I suggest we start accepting that mastitis is extremely painful, and
not just uncomfortable.
Gerda Spence Brussels, Belgium
Letters: Sexual discrepancy
Regarding the statistics of sexual partners. A village has 50 prostitutes,
150 nuns and 100 bachelors. The bachelors each savour all the prostitutes,
the nuns remain chaste. Thus the men have had an average of 50 partners
while the women have an average of (50×100+150×0)/200=25.
John Chapman Perth, Western Australia
Letters: Sexual discrepancy
Feedback (18 July) spotted the glaring discrepancy between the average
number of sexual partners claimed by French men (13), and French women (2
to 5). It just goes to show that you can use statistics to prove anything
you want (well 95 per cent of the time anyway).
However, I did wonder why the figure for women is quoted at between
2 and 5, if it is indeed an average. Are French women unable to remember
how many partners they have had?
Peter Calver North Harrow
Letters: Counting holes
I was surprised to see Edward van den Heuvel’s claim that his calculation
of the number of black holes in the Galaxy is original (Science, 11 July).
Roger Blandford made exactly the same calculation five years ago, and presented
it to the Newton Tercentenary meeting in Cambridge (see my book In Search
of the Edge of Time).
John Gribbin Newhaven, East Sussex
Letters: Freezing faster
This is often called the Mpemba effect, after Erasto Mpemba from Tanzania,
who observed it while making ice cream. A good account of his discovery
and subsequent experiments and a discussion of possible causes can be found
in Physics Education, vol 14, p 410 (1979). The effect had been noticed
as early as the 17th century by Bacon and Descartes, neither of whom could
explain this apparent anomaly.
Fraser Gordon, David Tilley University of Essex
Letters: Freezing faster
Other things being equal, Channon should realise that warm water is
significantly less dense than cold water. The warm water will also evaporate
far faster from an open beaker. If he starts with equal volumes, the mass
of ice in the ‘warm’ beaker will be less than that in the ‘cold’ beaker
at the end of his experiment! There is simply less water there to freeze!
Chris Reynolds Tring, Hertfordshire
Letters: Character count
Does it really require 50 characters on the envelope for Colin Bemrose
to write to his neighbour? (Feedback, 25 July). He could try writing to
me at 41, S17 4PN. If our postcode system is all it’s cracked up to be,
I should receive his letter the following morning. Some residential addresses
in this city require only six characters.
Correspondence from overseas requires the addition of just two characters,
UK.
Colin Singleton Sheffield