Q1 What does a barometer do?
Q2 How do I set my aneroid Barometer?
Q3 How do I compensate my barometer for my altitude?
Q4 Should I tap my Barometer?
Q5 How do I convert inches to millibars.
Q6 Should a barometer hang on an outside wall?
Q7 What is the brass coloured hand for?
Q8 My barometer points to fair but it is raining what is wrong?
Q9 Does my barometer need servicing?
Q10 Can I screw the adjuster at the base of my stick barometer
to make it read correctly?
Q11 I have heard that I can use a magnet to make the mercury
in my barometer join together, is this true?
Q12 How can I get my barograph drawing a line properly?
Q13 How can I make a barometer?
Q14 When do I change the battery in my barometer?
Q15 How do I clean the dial of my barometer?
Q16 How can I send a barometer to you for repair?
Q17 Is a mercury barometer more accurate than an aneroid?
Q18 What is an Otheometer?
Q19 How do I find my altitude?
Q20 I have heard mercury will be banned soon?
Q21 What is air pressure?
Q22 What size barograph paper do I require?
Q23 What books has Philip Collins written about Barometers?
Q24 How do I change the chart on my Barograph?
Q25 How do I check the wild oat Hygrometer?
Q26 How do I set a Barograph?
Q27 How do you set a Mercury Wheel Barometer?
Q28 Why are barometers seldom used outside?
Q1 What does a Barometer do? [top]
A barometer measures the weight of air above it at any time. As this weight
(or pressure) varies then we can often foretell the future days weather,
the barometer does not forecast, it is the person that uses the barometer
that makes the forecast.
Q2 How do I set my aneroid Barometer?
[top]
Once decided where to position your barometer, the screw at the back
of the barometer (sometimes visible through a small hole) should be turned
left or right to adjust the black indicating hand to read the correct
sea level reading. So, the idea being, everybody with an aneroid barometer
reads this at sea level reading regardless of the altitude at which they
are living. (For barographs adjustment of the knurled screw often near
the top of the mechanism will move the pen arm up and down to reach the
required reading.) Weather forecasters often give the air pressure during
forecasts particularly during settled weather which is the best time to
set a barometer. Alternatively, you can get the correct reading from a
Met office or Weather station or a known good barometer. In the UK you
can enter your postcode at the following link and get the reading nearest
to you, beware not to rely on this during times of changing pressure as
the data may not be updated more than once or twice a day. www.bbc.co.uk/weather
Some barometers read in inches of mercury, others in millibars or Hectar
Pascals, some in millimeters. Once set, your barometer should not need
resetting unless you move although you may wish to check it every year
or two.
Q3 How do I compensate my barometer for
my altitude? [top]
With aneroid barometers once set there should be no need to correct for
altitude as you should then always be reading your barometer as if it
was at sea level. With Stick barometers it may be necessary to add an
amount for altitude. The figures are available in tables but for general
domestic use the old calculation of adding 1/10 of an inch for every 100
feet above sea level is usually quite accurate enough. We do print a small
booklet on how to read the barometer from 1830's which we have added the
more accurate compensation tables if required (currently available at
£1.50 inc P & P in U.K.)
Q4 Should I tap my Barometer? [top]
Any dial barometer aneroid or mercury will always have
some amount of 'sticktion' therefore a GENTLE tap is normal.
(Tapping actually helps the user as it indicates which way the barometer
is moving at the time it is being looked at.)
Q5 How do I convert inches to millibars.
[top]
To convert inches to millibars multiply by 33.86
To convert millibars to inches multiply
by 0.02953
Q6 Should a barometer hang on an outside
wall? [top]
It makes no difference to the pressure reading which wall
you hang a barometer on. There may be a slight difference in temperature
but not pressure. The pressure is the same inside as well as outside.
Q7 What is the brass coloured hand for?
[top]
You normally adjust the brass hand so that it lines up with the blue(black
hand), you do this once a day usually in the morning and than you can
tell which way the pressure is moving and by how much in 24 hours.It is
more important to know the amount and direction of change than the actual
pressure to predict the weather.
Q8 My barometer points to fair but it is
raining what is wrong? [top]
A barometer measures air pressure and as such the words
should be ignored. It is more important to see which way the pressure
is moving, this will indicate the approaching weather more than the words.
Admiral Fitzroy coined a useful phrase which is as good today as it was
then.
Long foretold - Long Last
Short notice - Soon Past
Q9 Does my barometer need servicing?
[top]
Most aneroid (non-mercury type) barometers do not require a regular service.
A good aneroid will maintain reasonable accuracy for many years. Antique
aneroid barometers have generally suffered from old age and often benefit
from checking in the pressure chamber and will often need correction for
differences in the diaphragm movement. There is, over many years, a tendency
for the aneroid to loose some movement and become less sensitive, for this
reason a check and clean of the movement may be advisable perhaps between
25 and 50 years. Mercury barometers similarly will often last many
years most times getting damaged when moved. If all is working well then
they can be best left alone until they stop functioning or become 'sticky'
in their movement. Should you decide for us to overhaul any barometer we
request you DO NOT send until we have seen pictures and discussed method
of transport with you FIRST.
Q10 Can I screw the adjuster at the base of my stick barometer to make it read correctly?
[top]
If you have a fortin barometer, which is a metal tube with a glass reservoir
at the base and scale at the top it will be designed to adjust the level
of the mercury in the lower reservoir to the fuducial point which is a small
ivory point. This means that the reading will then be more accurate as it
is actually reading the true height of the mercury column. The divisions
on the scale will be precisely engraved as will the vernier. Many people
understandably confuse the adjusting screw,(more correctly called the transporting
screw) at the base of wood cased domestic barometers for the screw they
may have heard of or seen many years previous at school - college - university
- work etc. It is not for altering the level of mercury (except in a few
special types with level indictors on) but for restricting the movement
of the mercury in the reservoir and tube by reducing the volume. It lifts
up the leather base in the reservoir to do this, whilst it will appear to
raise the level of mercury and thereby 'correct' the barometer to read as
if it was at sea level it will restrict the mercury from being able to fall
when the pressure falls and only work when the pressure increases. Generally
this transport screw should be unscrewed so as not to interfere with mercury
level. On a few occasions it may be possible to support the leather and
make very minor adjustments to the level but this is coincidental and not
the normal procedure.
Q11 I have heard that I can use a magnet to make the mercury in my barometer join together, is this true? [top]
This is a common misunderstanding, perhaps confusing the magnet used on
a minimum and maximum thermometer to re-set the small steel level indictors.
Mercury is non magnetic and will not join together what is probably an air
gap. To rectify this problem it will need to be taken to a suitably skilled
barometer specialist. It should not be sent or posted!
Q12 How can I get my barograph drawing a line properly? [top]
Barographs of the traditional type use a wet ink bucket style nib. You
should put a drop or two into the bucket of the nib and it should write
reasonably even line. If it does not then you should check the following.
Is the paper the correct type? it must be a special grade of paper that
will not soak up the ink but will absorb a small amount of it. (Photo copies
will not do) You should also have the correct ink for the paper and there
are different types of recording inks. The pen should be in good condition,
it may need cleaning carefully but if very old and corroded may need replacing.
Our paper and ink work well together. We can not guarantee our ink on other
paper or paper with our ink. It is normal to add a drop or two of ink every
2 or 3 weeks, if you are putting more than 2 drops a week in then something
is probably not right! Nibs can be adjusted by altering the gap between
the points carefully , they should be of even length and the wider apart
they are the fatter the line is drawn. It is common with new nibs or nibs
that have not been used for some time to be dry on the ends and even with
ink in them they will not draw a line. This is because the nib works by
capillary action (like a fountain pen) It may often be necessary to start
a new or very dry nib by using a small needle or pin etc to put ink on the
paper, once started the nib will continue to draw a line until the ink is
exhausted. Then a drop more will work easily. Blotching of ink is often
a sign of incorect or not matching paper and ink. Our director Philip Collins
wrote a useful book about barographs a few years ago which will assist many
poeple in understanding the types of barographs, ages etc, and has a bit
about general use and care, the book, as well as charts, ink and nibs can
be bought online direct from us at BAROGRAPH
PARTS
Q13 How can I make a barometer? [top]
Occasionally we are asked how to make a barometer. We make many types and
believe me it is not that easy. Most people have a set type in mind, often
a mercurial stick. Our services do not extend to assisting for the many
hours necessary to teach someone to make their own barometer but if you
have an idea about which type of barometer you may wish to make then send
a picture or sketch and we can estimate the parts that may be needed to
make such a piece. The barometers we make need special parts making which
we often do to suit the individual barometer we are making,(that is why
most of ours cost so much! they can take more than 100 hours of skilled
labour to complete and many hundreds of pounds of parts.)
The simplist form of stick barometer will be one with a glass tube and
this can be positioned along side a scale to read the pressure, the decorative
case can be as simple or elaborate as is liked. Our own designs are normally
based on antique models.
Q14 When do I change the battery in my barometer?
[top]
So far as we know only electronic types have batteries, these will need
changing when they no longer work. The usual aneroid or mercury barometer
does not have a battery so will not need changing.
Q15 How do I clean the dial of my barometer? [top]
Most dials on antique barometers will be silvered brass and can not normally
be cleaned at home. This really is a job for the specialist restorer. Other
dials such as glass, card and ceramic need special care later barometers
from about 1920's have aluminium dials which can not be cleaned.
Q16 How can I send a barometer to you for repair? [top]
There are many different types of barometers, We request that you DO NOT
send us any item before first contacting us preferably with a picture of
the barometer. We can then advise if a repair may be possible, likely cost
and how best to send or arrange for sending the item to us. Remember to
include your address and other details.
Q17 Is a mercury barometer more accurate than an aneroid? [top]
Well it will depend on just what they are both like. You could ask a similar
question about cars, is a petrol car better than a diesel car? The answer
in both cases is that it will greatly depend on how well made they both
are and what condition they are in. Aneroid barometers generally are similar
in accuracy to mercury barometers, both do have some small errors even if
made well. There are accurate aneroid barometers and accurate mercury stick
barometers which will normally be Fortin or Kew pattern ones - built for
scientific accuracy not looks!
Q18. What is an Otheometer? [top]
Well Robert Hooke made an Otheometer but no drawings survive. It worked
opposite to a barometer and the root of the word is derived from othe- to
push so it is some type of push meter. probably a type of weather glass.
With our fascination in barometers we have re-designed this instrument based
on Mr Collins experience and knowledge of old barometers and weather glasses.
We are pleased to offer our own 'Hooke's Otheometer' for sale with accurately
engraved style of paper charts and special patented tube which as Robert
Hooke's Otheometer, moves down for low pressure and up for higher pressures.
please contact us for details if you wish to have a truely unusual barometer!
Q19. How do I find my altitude? [top]
Try looking on an ordnance survey map - the contour lines are at set altitudes
and with a good pair of eyes you should be able to work out your altitude
within a few meters. Knowing your altitude is not necessary for setting
a barometer. Provided you are not over 1000 feet then most will adjust easily,
if higher than 1000 feet some adjustment may be needed in a workshop and
so the altitude where the barometer will be is needed.
Q20 Is mercury banned? [top]
The E U have agreed a ban on the sale of New Mercury Measuring instruments
including New Barometers. This came into force in October 2009. The sale
of second hand and antique barometers as well as their repair has not and
is not in any way threatened at the moment. Dispite the fact that we make
a few barometers and our glass blower makes tubes for repairs as well as
new ones in future we will only be able to offer tubes for restoration.
Of course if we sell a tube we do not know what it will be used for and
as it does not have a scale on it it will not be a barometer - an interesting
question. We may well be able to sell a barometer case without a mercury
tube in it as well.
The ban is in order to stop tons of mercury that pollutes the world especially Europe, the likeley fact is that the UK manufacture of new domestic stick barometers accounts for less than 20 kilos of mercury per year - little of which is likely to get into the food chain or be wasted - begs the question as to how the tons of mercury currently entering into the food chain is getting there! certainly not by barometers!
The UK burns coal in its power industry (we import 491 Million Tons per year!) and it is reported that the small amount of trace mercury sometimes found in coal is polluting the atmosphere with mercury vapours which turn to methyl mercury and settles and pollutes Europe. For many decades the UK and other countries have been using mercury amalgam fillings, and excellent they are as well. But what happens to the fillings when they get cremated? - into the atmosphere with the smoke! how many cremations a year do we have in the UK alone?
Florecent lights have a small amount of mercury in them, any chance of banning them - NO! (I asked the EU and they think there is no alternative so no ban in sight) what if the light manufacturers were taxed 1 euro for every bulb made? that would produce funds to help tackle the mercury waste problem. Where do old flourecent light bulbs end up? well the regulations state that they should not be sent to land fill (mercury might leak out of them) so where do you send them? well if you are really dedicated to saving the enviroment you search around until you find a special bank to collect them (at a cost) or like us you arrange collection and they end up with Mercury Recycling in Manchester (tel 0161 877 0977) who correctly re-cycle them and extract the mercury. Where does your company or council get rid of its flourecent light bulbs? chances are normal waste! where do you dispose of yours?
But never mind EU are banning the faithfull domestic barometers so all will be well with the plant earth and mercury pollution will be a thing of the past! Dream on European masters.
watch our NEWS section of this website for more recent updates as they occur.
Q21 What is air pressure?
[top]
Q22 What size barograph paper do I require? [top]
We are often asked what charts suit someones barograph, and to be honest
it is very difficult to know over the phone. Regrettably we do not know
all the models ever made, there were many variations. However many accept
standard type charts. Our most common types is ref 1005750 which is 300mm
long and 90mm high in millibars, we also have ref 1005775 which is a MET
office style chart which measures 306mm by 90mm high both measure vertically
950 to 1050 millibars. To get the best fit chart we always suggest to start
from the beginning. Often charts that are being used are not the original
ones anyway but came with the barograph or were only ones available at the
time. So measure the circumference of the drum by wrapping a piece of paper
around the drum and marking were the two ends overlap, add about 5mm to
this measurement and this is approx the length of chart required, it can
be a little longer but hardly any shorter. Then measure the height of the
drum, a chart should not exceed the height of the drum and often can be
1 or 2mm shorter. Our standard charts are available to be seen and ordered
at www.barometerspareparts.co.uk
Many different types were made over last 125 years, on occasions we can
arrange special reprinting of charts to suit a more unusual item but quantities
often need to be 1000 to defray cost of set up of printing machine and artwork
preparation. If best time keeping is required then this will need to be
checked by starting the barograph and marking the beginning of a chart after
an hour or so (to allow the clockwork gears to catch up any slack) after
exactly 7 full days (168 hours) mark the chart again and measure the length
- seldom does anyone ask for such accuracy but it gives a guide as to the
length of printing required for 7 full days. Barograph makers years ago
supplied many similar barographs but with slightly different time speeds.
Also to check is the range of the barograph, this is harder and our own
manufacturing and restoration involves testing in a pressure chamber and
calibrating the barograph accordingly. However most old barographs of common
size will generally measure 3 inches of mercury from 28 to 31 vertically
(on a curved graph) millibars equivalent is 950 to 1050 usually. Another
couple of factors to consider is the measurements required in terms of pressure
readings, we sell millibar charts as well as inch measuring charts which
is rather old fashioned these days, the weather reports use millibars on
TV and Radio. The 2nd consideration is whether the charts you require are
held on with a clip of some type of if no clip then need to be adhesive.
We sell both adhesive and non adhesive, the adhesive ones are more expensive
and unnecessary if your barograph has a clip system to secure the charts
in position. Most of our charts are also printed in old fashioned colours
as many old charts were, green, orange or red charts, we think they look
better than boring old grey. We probably supply 75% of the standard type
of charts and certainly without the actual item to undertake the above checks
we would be unable to be certain which might suit best. If you have a different
size drum than the charts we have then e-mail us a picture of the barograph
with the lid (or cover) open so we can see the design etc. It may be possible
to use something close or we may be able to supply blank paper for you to
print your own small numbers of charts - the paper is a special type for
the ink that is used. Hope that helps.
Q23 What books has Philip Collins written about Barometers?[top]
Q24 How do I change the chart on my Barograph?[top]
Q25 How do I check the wild oat Hygrometer[top]
Q26 How do you set a Barograph?[top]
Q27 How do you set a Mercury Wheel Barometer?[top]
Q28 Why are barometers seldom used outside? [top]
In actual fact a few barometers are used outside - such as those used for
measuring altitude either above or below sea level for a variety of reasons
such as water pressure supply, walking and climbing, reading maps, ordanance
aiming and several other reasons. For weather prediction, the main use of
a domestic barometer, then very few are used outside. There are some designed
for public display such as rare ones on church towers or public buildings
more for loccal interest than serious weather prediction. Famously Admiral
FitzRoy placed some around the coast for publc use when barometers were
more expensive and only the rich would own one. These days barometers are
primarily used indoors because the pressure inside the house is the same
as outside the house (unless you live in a totally sealed envirment - which
is rare indeed).
However if you want to know the pressure to attempt to predict the weather
then a nice decorative barometer fares better in the more aimable climate
of a house than outside.