Tongue tied
Question: What are those little flaps of skin arranged in two rows under the
tongue called and what is their function?
Answer: The two flaps of skin that you are seeing underneath the tongue are
located on either side of the submandibular duct (the bottom of the cord in the
middle). They are the sublingual folds and these serve as part of the mucosal
lining of the mouth and they cover the salivary glands.
However, if you are referring to the flaps that appear on the underside of
the tongue itself, these are called the plica fimbriata. The deep lingual vein
runs underneath these structures and this is why they are there鈥攖hey cover
the vein to protect it and they also compensate for it when the tongue
moves.
Advertisement
Benjamin Spletzer
by e-mail, no address supplied
Heating disorder
Question: I use hot water only in the morning and after work. Is it more
economical to leave my gas water boiler on constantly or to set it to come on
twice a day?
Answer: These sorts of questions were often asked by members of the public
who were concerned about their heating bills and overuse of scarce resources
during the energy crisis of the early 1970s.
The answer that was most often given on television and in the newspapers was
to leave the heating on, because it takes more energy to heat up the water again
and again than it does to keep the system running. This is, of course, a
fallacy.
Apart from the heat which is required to warm any additional water after some
of it has been drawn off via hot water taps, the heat supplied to a boiler
replaces heat losses to its surroundings.
Newton showed 300 years ago that the rate of heat loss from a system is
proportional to the temperature difference between it and its surroundings.
If no heat is applied, as the system cools down, the rate of loss decreases
until, as the temperature reaches that of the surroundings, there are no further
heat losses. When the heat source is subsequently turned on again, the heat
supplied simply replaces those losses.
For a heater which is kept on constantly, the temperature and the rate of
heat loss remain high. The heater is continually replacing these higher heat
losses.
If a boiler has perfect insulation there will be no heat loss, and it makes
no difference whether its heater is left on constantly or not. With
less-than-perfect insulation, which is obviously the norm, it would be more
economical to set the timer so that the boiler comes on twice a day.
P. Smith
Long Ashton, Somerset
Berry worry
Question: Why does one blackberry often ripen well before an adjacent
blackberry on the same bush?
(continued)
Answer: I have observed that many plants with multiple flowers do not all
open them all at the same time. Initially only a few open. If these early
flowers are pollinated, the rest will open a few days later鈥� if not, there
is a much longer delay and then another 鈥渟couting鈥� flower opens and awaits
pollination.
If the fruit of the plant is a multiple berry, the first flower gets the full
treatment and then usually goes on to form the best single fruit.
Knowing this, a skilled gardener can delay flowering of the plants by
ensuring that there is no pollination of the scouting flowers and therefore
large berries at each of these points. Thanks to this, the ripest and juiciest
berries can be artificially cultivated.
Douglas Nelson
Averon-Bergelle, France
This week鈥檚 questions
Eggstrapolate please: Does anybody have a formula to calculate the correct
boiling time for a soft-boiled egg, given its weight and initial
temperature?
And which gives better results: starting with an egg that is at room
temperature or one at 5 掳C, and does putting it into cold water or boiling
water make a difference?
I imagine that to get the hardest white and softest yolk one would put an egg
from the fridge into boiling water, but they are likely to crack. How do you
avoid this?
Chris Finn
Beverley, East Yorkshire
Greener and greener: When waste paper is recycled the new product is clearly
of a poorer quality than the original paper. Is there a further deterioration if
recycled paper is itself recycled?
Can papers recycled several times be separated from nonrecycled waste paper?
And is there a limit to the number of cycles that constituent materials can go
through?
Michael Ghirelli
Hillesden, Buckinghamshire
Watermarks: When the tide is going out, the sea (at least here in Belgium)
leaves the shelves on a sandy beach in nice quasi-geometric rows and not
scattered all over the place. Why is this?
Philip Spriet
Bornem, Belgium
Backwash brio: When filling a can from a petrol station hand pump in
preparation for the summer grass-mowing routine, I have noticed that no matter
how hard I try, it is impossible to overfill the can.
The automatic stop mechanism on the petrol pump can detect the smallest
amount of back pressure (if that鈥檚 how it works). Can anyone explain how this
mechanism does its job so well?
Roger Rowland
by e-mail, no address supplied.
Who dose? If there are more than 200 different viruses which are capable of
causing the common cold in humans, is it possible to catch several colds at
once, with each cold being caused by a different virus?
Does immunity that has been built up against one of the viruses work against
any of the others?
Leigh Sprague
by e-mail, no address supplied
Waterfall: On a riverboat trip in Ghent in Belgium I noticed that, as the bow
of our boat passed a point on the shore, the water level at the bank at that
point began to drop. We were travelling at about 5 knots. By the time the point
was amidships the level was down at least 10 centimetres. This was several
seconds before the bow wave of the boat reached the bank.
The effect was particularly noticeable where there were piles along the river
bank because the water would gush out from behind them, although there was no
apparent backwards motion of floating debris as you would expect if water were
being drawn into the bow wake.
What was happening and where did all the missing water go to?
C. R. Cavonius
University of Dortmund, Germany