You won't believe your eyes
I was interested to read that Lloyd Kaufman has further experimental evidence
for the now generally accepted explanation he put forward in the 1960s for the
illusion of a large Moon on the horizon
(15 January, p 12). That is, the Moon
looks large when it is full and close to the horizon because our sky dome is not
a true hemisphere and we perceive the sky above to be closer to us than the
horizon.
It is easy to remove the horizon signals from the brain by closing one eye
and viewing the Moon with the other eye through a small hole, such as can easily
be formed with the root of the thumb and first finger. When you look at the Moon
in this way it suddenly returns to its normal, smaller size and distance.
For a more interesting and less well-known phenomenon, keep one eye looking
through the small hole and then open the other eye to look directly at the Moon.
The effect is dramatic鈥攜ou can see two entirely different sized Moons
simultaneously. Go slightly cross-eyed and you can play with the two Moons,
sliding them together or separating them at will.
Whatever tricks your brain is playing to create the illusion of a large Moon
it can, at one and the same time, discard them. I strongly urge readers who have
not seen this extraordinary phenomenon to look for it within a few days of a
full Moon. The next full Moon is on 19 February.
Celtic tiger
I refer to the comments concerning the Irish famine and the possibilities of
genetically modified technology. Your correspondent Joe Hartney
(15 January, p 50)
correctly outlines the political situation when the life of the Irish
peasant meant nothing to the British landlord, who took most of the crops the
peasants grew as rent, leaving only potatoes as the staple diet. So the areas of
biology and politics intertwined, as they still do today.
However, to say that this was the “true cause” of the famine is not
completely accurate. A severe fungal infection did ruin the “organic” crop of
potatoes that was the only foodstuff left for millions of Irish rural tenants.
Had the Irish invented GM technology to stop famine happening again, I am sure
they would have implemented it immediately to replace the organic farming
methods that had let the rural community down.
Ireland has embraced many new technologies in the past to break its political
and economic reliance on its old neighbour and allow it stand alone as a nation.
A perfect example of this is the fact that Ireland is currently the second
largest producer of software in the world, second only to the US. Ireland today
has been dubbed the “Celtic tiger” of the West.
There are numerous factors to the Irish famine and to use it as a “spin” in
either direction in the GM debate reflects a lack of understanding.
Big bad bird?
I want to set the record straight on the cassowary’s supposed aggression
(4 December 1999, p 13).
It is not the bird that is aggressive, but us, with our
fences, roads and dogs.
We invade the habitat of this big bird and woo it with easy food. We soon
have it eating out of our hands. It is at this point that we have sealed its
fate, for the cassowary will now run up to people鈥攊n cars or on
foot鈥攁nd check them out for food with a nudge and a push.
This can be daunting indeed and more than likely misconstrued as aggression.
However, hand feeding should not be confused with setting up feeding stations to
supplement the cassowaries’ diet when their diminishing rural environment cannot
support the population.
Feeding stations are carefully planned to make the right sort of food
available in a way that is not associated with people.
It is also important that the seeds of fruit that don’t belong in the forest
are not fed to the birds and dispersed by them. We must not inadvertently
undermine the ability of the natural environment to support the birds.
If left alone, cassowaries are, in fact, nervous and afraid of people,
retiring silently into the darkness of the forest if people approach.
Seeing shapes
Interpretation of leaf shape has enticed Lynn Dicks into a quagmire which has
entrapped many a botanist during the past century or two
(25 December 1999, p 26).
Similarly shaped leaves occur so often in different environments, that many
plant names reflect the fact. For example, the aquatic ivy-leaved crowfoot,
Ranunculus hederaceus, has floating leaves that resemble the lobed leaves
of common ivy, Hedera helix, a land plant. Such facts make it very
difficult to interpret the function of leaf shape, and it is far too easy to
look for a simple explanation when there are so many variables.
Flushing success
B. McManus’s patented gadget, which is designed to tell you when your toilet
cistern is about to overflow, is an example of a costly method of solving a
self-imposed and unnecessary difficulty
(25 December 1999, p 9).
If a flap valve flush were used instead of the primitive siphon flush, the
excess water would simply enter the pedestal audibly and visibly, and there
would be no need for an outside overflow.
After decades of use in North America, Japan and much of the Continent, the
flap (or drop) valve was finally approved last July for installation in British
lavatories.
Body sensing bags
Your article on car airbags reported that a Swedish company is working on
airbags that cushion a person all the way round in a crash
(8 January, p 7).
However, I hope these new airbags will be fitted with sensors to measure a
person’s height and build. Many people have already been killed by car airbags
in Britain. A small woman who sits close to the steering wheel is particularly
at risk from death or serious injury, even in a minor collision, as the force of
an airbag inflating can do a lot of damage to head and face. Sensors could
remove this danger, but unfortunately most manufacturers do not use them.
Letter
Your correspondent Alan Elkan
(25 December, p 86) is slightly mistaken
regarding car airbags. They were indeed first introduced in America because
seatbelts were not often used there, but they have also proved invaluable in
Europe in conjunction with a seatbelt.
Airbags reduce face and chest injuries from the steering wheel. Door or
seat-mounted bags can also provide side impact protection. A seatbelt is
certainly the best protection in a crash, but the airbag has an important role
to play as well.
Blues for Santa
I like the American definition of a bluenose
(Feedback, 8 January), but woe
betide anyone sending a card with a bluenosed reindeer to a supporter of Celtic
football club, as everyone in Scotland knows that a bluenose is a fervent
Glasgow Rangers supporter, and the enmity between these fans is legendary.
Letter
The reindeer mentioned in Feedback was probably one of Santa’s. They move so
fast on Christmas Eve that they are subject to the Doppler effect. A blue nose
means that the reindeer is rushing towards us. Rudolph is normally seen moving
away, hence the usual red nose.