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Here follows a variety of articles, some by Philip Collins, which may be
of interest to barometer lovers:
ADMIRAL FITZROY'S REMARKS ON THE CAMPHOR GLASS
(taken from "The Weather Book" circa 1850)
Having often noticed peculiar effects on certain instruments, used as weather
glasses, that did not seem to be caused by pressure, or solely by temperature,
by dryness, or by moisture - having found that these alterations happened
with electric changes in thatmosphere that were not always preceded or accompanied
by movement of mercury in a barometer, and that, among other peculiarities,
increase or diminution of winds, in the very 'heart' of the trades, caused
effects on them, while the mercurial column remained unaltered, or showed
only the slight inter-tropical diurnal change (as regular there as a clock),
we have long felt sure that another agent might be traced.
Considerably more than a century ago what were called 'storm glasses' were
made in this country. Who was the inventor, is now very uncertain; but they
were sold on old London Bridge, at the sign of the "Looking Glass".
Since 1825 we have generally had some of the vials, as curiosities rather
than otherwise, for nothing certain could be made of their variations until
lately, when it was fairly demonstrated that if fixed, undisturbed, in free
air, not exposed to radiation, fire or sun, but in the ordinary light of
a well-ventilated room, or, preferably, in the outer air, the chemical mixture
in a so-called storm glass varies in character with the direction of the
wind - not its force, specially, though it may so vary (in appearance only)
from another cause, electrical tension.
As the atmospheric current veers towards, comes from, or is only approaching
from the polar direction, this chemical mixture - if closely, even microscopically
watched, - is found to grow like fir, yew, or fern leaves - or like hoar
frost - or even large but delicate crystallisations.
As the wind, or great body of air, tends more from the opposite quarter,
the lines or spikes - all the regular, hard, or crisp features, gradually
soften and diminish till they vanish.
Before and in a continued southerly wind the mixture sinks slowly downwrd
in the vial, till it becomes shapeless, like melting white sugar.
Before or during the continuance of a northerly wind (polar current), the
crystallisations are beautiful (if the mixture is correct, the glass a fixture,
and duly placed); but the least motion of the liquid disturbs them.
When the main air-currents meet, and turn towards the west, making easterly
winds, stars are more or less numerous, and the liquid dull, or less clear.
When, and while they combine by the west, making westerly wind, the liquid
is clear, and the crystallisation well defined, without loose stars.
While any hard or crisp features are visible below, above, or at the top
of the liquid (where they form for polar wind) there is plus electricity
in the air; a mixture of polar current co-exisiting in that locality with
the opposite, or southerly.
When nothing but soft, melting, sugary substance is seen, the atmospheric
current (feeble or strong as it may be) is southerly with minus electricity,
unmixed with and uninfluenced by the contrary wind.
Repeated trials with a delicate galvanometer, applied to measure electric
tension in the air, have proved these facts, which are now found useful
for aiding, with the barometer and thermometers, in forecasting weather.
Temperature affects the mixture much, but not solely; as many comparisons
of winter with summer changes of temperature have fully demonstrated.
A confused appearance of the mixture, with flaky spots, or stars, in motion,
and less clearness of the liquid, indicates south-easterly wind, probably
strong - to a gale.
Clearness of the liquid, with more or less perfect crystallisations, accompanies
a combination, or a contest, of the main currents, by the west, and very
remarkable these differences are - the results of these air currents acting
on each other from eastward, or entirely from an opposite direction, the
west.
The glass should be wiped clean, now and then, - and two or three times
in a year the mixture should be disturbed, by inverting and gently shaking
the glass vial.
The composition is camphor - nitrate of potassium and sal-ammoniac - partly
dissolved by alcohol, with water, and some air, in hermetically sealed glass.
There are many imitations, more or less incorrectly made.
Those camphor glasses used by the writer lately were prepared by Messrs.
Negretti and Zambra. There are numerous others, some of which are inexact
in chemical composition; and are not nearly so sensitive.
Various BOOKS AVAILABLE BY POST OR COLLECT
New book on Barographs due in 2001
A Treatise on Meteorological Instruments by Negretti & Zambra
This treatise was first published in 1864. The authors describe the method
of construction, the scientific principles and practical uses of barometers,
thermometers, hygrometers, rain gauges, anemometers, electrometers, ozonometers
and other meteorological instruments. With the help of 98 illustrations
and 19 tables every instrument is fully described and there are adequate
directions on how they should be used. The authors, Enrico (Henry) Negretti
and Joseph Zambra were Italians who formed the partnership of Negretti &
Zambra in London in 1850 as philosophical instrument makers and became the
most prolific and leading makers of meteorological instruments during the
second half of the nineteenth century.
Softback. 159 pages. £7.95
The Banfield Family Collection of Barometers by Edwin Banfield £6.95
An illustrated guide to the Banfield Family Collection of Barometers housed
at Barometer World, Merton, Okehampton, Devon. Includes an introduction
to the collection and a short description of each instrument, including
the estimated date of manufacture. 280 stick, wheel and aneroid barometers
and barographs made between 1680 and the present day. Softback. Over 300
photographs.
The History of the Barometer by W E Knowles Middleton £24.95
This book was first published in 1964 and was out of print for around 20
years until it's reprint in 1994. It is the acknowledged authority on the
subject of barometers and is the first and only complete world history of
the mercury, aneroid and all other barometers, including barographs. Essential
reading for every barometer enthusiast. Hardback. 512 pages. 197 illustrations.
The Italian Influence on English Barometers from 1780 by Edwin Banfield
£7.95
The author traces the origins and background of the early Italian migrant
barometer makers. He discusses the Italian influence on the style and design
of wheel, stick and aneroid barometers and explains how they were able to
dominate the British market. Three chapters cover important Italian makers.
A fascinating history. Softback. 160 pages. 200 illustrations.
Barometer Makers and Retailers 1660 - 1900 by Edwin Banfield £9.95
An alphabetical list of more than 4000 makers and retailers who were active
in England, Scotland, Wales and Ireland. Information includes makers working
or estimated working dates, the business addresses where known and other
items of interest. Softback. 256 pages. 28 illustrations.
Antique Barometers: An Illustrated Survey by Edwin Banfield £6.95
A reprint of a popular guide to stick, wheel and aneroid barometers and
barographs. Softback. 128 pages. 118 illustrations.
Barometers: Stick or Cistern Tube by Edwin Banfield £14.95
The author traces the history of the domestic, marine, station, Fitzroy,
angle, double-angle and two-liquid barometers. Hardback. 256 pages. 296
illustrations.
Barometers: Wheel or Banjo by Edwin Banfield £11.95
The book traces the history and development of wheel barometers from 1663
to the twentieth century.
Hardback. 160 pages. 165 illustrations.
Barometers: Aneroid and Barographs by Edwin Banfield £11.95
The author describes the development of domestic, marine, traveller's and
mountain barometers, barographs, storm glasses and weather houses. Hardback.
160 pages. 130 illustrations.
Care & Restoration of Barometers by Philip R Collins £6.95
The author describes in detail how to restore wheel barometers and touches
on stick and aneroid barometers. He also gives advice on how they should
be handled and maintained. Softback. 128 pages. 175 illustrations.
Barometers by Anita McConnell £2.25
A brief outline of the development of barometers and the many types with
good illustrations, some from original catalogues. A comprehensive little
book. Paperback. 32 pages. 50 illustrations.
Vulgar & Mechanick, The Scientific Instrument Trade in Ireland, 1650
- 1921
by J E Burnett & A D Morrison-Low £15.00
A useful addition for the barometer enthusiast covering scientific instrument
makers in Ireland, some of whom made barometers. Hardback. 166 pages. 53
illustrations.
Brass & Glass, Scientific Instrument Making Workshops in Scotland
by T N Clarke, A D Morrison-Low and A D C Simpson £25.00
Another useful addition, covering scientific instrument makers in Scotland,
some of whom were barometer makers. In-depth study of several interesting
firms with excellent photographs. Well researched. Softback. 320 pages.
218 illustrations.
English Barometers 1680 - 1860 by Sir Nicholas Goodison £45.00
High quality print and photographs. Covers development and history of the
barometer, highlights individual makers and list some makers and retailers.
Hardback. 388 pages. Over 200 illustrations.
Directory of British Scientific Instrument Makers 1550 - 1851 by Gloria
Clifton £65
Aneroid Barometers and their Restoration by Philip Collins £18.95
Explores the history and development of the aneroid barometer since 1844.
Deals in detail with restoring aneroid barometers, particularly the movements,
and is the only book available on repairing them. Hardback 209 pages. Illustrations,
some colour plates.
CHILDREN'S BOOKS
The Weather - Usborne Spotter's Guide £3.50
Ideal field guide for both children and adults. Deals with the basic elements
that cause all weather and explains how these elements combine to produce
different kinds of clouds, winds, precipitation and storms - everything
from dew to tornadoes. Describes how weathermen forecast the weather and
tells you how to use and make simple weather recording instruments. Paperback.
64 pages.
What Makes it Rain? - Usborne Starting Point Science £2.99
Simple text, detailed illustrations and lively cartoons combine to answer
the question in clear, step-by-step stages. Aimed at children of 6 years
and upwards. Paperback. 24 pages.
A clear and comprehensive introduction to all aspects of the world's weather
and climates and suggests many activities to help you understand the processes
which form different weather phenomena. Packed with clearly explained activities,
experiments and projects. Aimed at 10-16 year olds. Paperback. 48 pages.
My Science Book of Weather - Dorling Kindersley £6.99
Finding out about science becomes fun with this practical activity book.
Packed with projects and simple experiments which can be carried out at
home. Introduces the basic principles of science. Hard back. 29 pages.
Why does lightning strike? - Dorling Kindersley £4.99
Questions children ask about the weather. Hard back. 21 pages.
Weather - Eyewitness Guide £9.99
Discover the world's weather - why it rains, how clouds form, what causes
a hurricane and where you might see a tornado. Hard back. 63 pages.
How The Weather Works - Eyewitness Science Guide £14.99
An original introduction to the weather, filled with hundreds of experiments
to discover the way the weather works. Suitable for Key Stages 2,3, and
4 of the National Curriculum. Hard back. 192 pages.
Weather - Dorling Kindersley Explorers £4.99
How to watch and understand the weather and its changes with things to make
and do. Softback. 59 pages.
Weather Facts - Dorling Kindersley £4.99
Pocket reference guide with superb full colour photographs, explaining causes
and effects of all kinds of weather. Paperback. 160 pages.
Science with Weather - Usborne Science Activities £4.95
Activities to help young children learn about the weather. Hard back. 24
pages
OTHER BOOKS
Red Sky at Night, Shepherd's Delight £12 Paul J Marriott. Hard
back 355 pages. Weather lore of the English countryside with 1900 sayings
explained and tested.
POSTAGE EXTRA
(price of postage for all overseas orders on application)
WILD OATS
Many antique mercurial barometers incorporate a hygrometer, these were actually
operated by part of a wild oat. The upright stem referred to is more commonly
called the Oatbeard obtained from the wild oat seed. When magnified
one can see that its structure is that of a twisted fibre, like that of
a rope, and has been used for its natural ability to twist to the right
when moistened, and to the left when drying. The rate of movement will vary
from oatbeard to oatbeard as they vary slightly in length and thickness.
Some turn two or three revolutions when moistened and some will turn even
more. This action stands the seed upwards with the aid of the tail, or arm,
which is set at right angles to enable the seed therefore to locate a crack
or crevice in the soil structure of the ground in which to drop, thereby
increasing its chances of propagation.
The use in the hygrometer dials of antique barometers was commonplace up
until approximately 1840 when some makers must presumably have tried to
cut corners on production costs. Generally barometers not originally fitted
with wild oatbeards are of poor quality in some of the finer details. This
tendency seemed to increase as the years went by, perhaps the start of mass
production! And more profit! Although there are fine examples of operational
hygrometers with oatbeards after 1840, they seem to be almost non existent
after the 1870's. The typical barometer which did not usually have an oatbeard
fitted is the 'onion' or 'tulip' design barometer. A cross section of the
middle of the hygrometer dial often encountered on such barometers, fig.
2, and of the earlier style, fig. 1 - which actually works (!) - illustrates
this progression. When using an oatbeard, some support is needed, even when
only slightly encumbered with a dried grass pointer, to enable the pointer
to revolve near enough parallel to the dial and not twist up to the glass
or down to touch the dial. This is provided by a brass tube surrounding
the oatbeard. It is interesting to note that on some early stick barometers
circa 1790 and earlier, which are fitted with oatbeard hygrometers, the
allowance for length of the beard is greater than most normal wheel barometers
of later date. It is perhaps possible that in the 18th century larger oatbeards
were more commonly available or found than the ones which are used today.
As an experiment wild oats have been grown which have oatbeards of approximately
1/2" long and operate well when used as described, but accuracy is
just not available; the best one can hope for is a comparative indication.
The divisions on the dial are almost meaningless. Although few people observe
their hygrometers, the only satisfactory course when restoring them is to
make it as near the original as possible.
ADIE'S SYMPIESOMETER
Alexander Adie, born in Edinburgh in 1775, was apprenticed to his uncle
John Miller, a leading 18th century Scottish instrument maker, and became
his partner in 1804. Adie had a great interest in meteorological instruments
and in 1818 he invented an improved air barometer, known as the sympiesometer,
and obtained a British Patent No. 4323.
Adie's sympiesometer was made by both himself and others. It has a bulb
filled with hydrogen and another bulb which, with part of the connecting
tube, contains coloured almond oil. A thermometer is also mounted. The scale
of pressures is made to slide against a fixed scale of temperatures, both
being graduated. To use the instrument, the thermometer is first read and
an index pointer on the slide is set to correspond with the reading of the
thermometer. The pressure is then read from the sliding scale opposite the
level of the oil in the tube and the pressure reading can be recorded on
the small dial at the base of the sympiesometer.
The sympiesometer was calibrated by comparison with an ordinary barometer
in a pressure-vacuum chamber, and the scale was calibrated by varying the
temperature with the pressure constant at some mean value. The correction
for temperature will, of course, be exact only at this pressure.
Adie had his sympiesometer tested on ships in the Tropics, the Arctic, and
near the coast of Scotland. All the reports received seem to have been enthusiastic.
A letter from the Commander of the Isabella, one of the ships on
the Ross expedition to the Arctic, states:
"The Sympiesometer is a most excellent instrument, and shews the weather
far better than the marine barometer. In short, the barometer is of no use
compared to it . . . in my opinion it surpasses the mercurial barometer
as much as the barometer is superior to having none at all."
In 1829 the well known Scottish scientist James Forbes commented: "as
a marine barometer, its superiority in accuracy and utility, as well as
convenience, seems fully established".
We have handled old examples of these in the past and have found some to
be still working after 100 years. Our replica is another quality facismile
of this original instrument. Although we do not suggest it is as accurate
as a conventional barometer, it certainly is an intriguing variation of
a barometer.
BAROMETER WORLD LTD
MERTON, DEVON. EX20 3DS
TEL: 01805 603443 FAX: 01805 603344
THE MAGDEBURG EXPERIMENT
National Science Week can be praised for encouraging people throughout the
country to enter into many types of science projects. This year we were
fortunate to be grant aided by Copus, the committee of public understanding
of science, to re-enact the complete Magdeburg Experiment. For those readers
who are not aware of this it is a 17th century experiment first carried
out by Otto Von Guericke in Magdeburg, Germany. Otto Von Guericke, 1602
- 1686, was an incredible natural scientist. In 1654 he designed a vacuum
pump to withdraw air from vessels. In 1643 Torricelli had made the first
barometer, after taking over notes from Galileo and in those days work on
the vacuum was very much in the forefront of pioneering science. It is without
doubt that Otto Von Guericke, considered to be the 'father of the vacuum',
was a showman and he carried out a number of public experiments on vacuums
and pressure. Robert Boyle took over much of the continuation and furtherance
of his work in Britain.
The original experiment grew out of smaller hemispheres and indeed such
was the cost of these hemispheres in productions that even the rich Otto
Von Guericke could not afford to continue all of this work as he may have
liked to. But in 1657 he demonstrated in front of Ferdinand III, and other
people, the tremendous weight of air around us. He believed that the air
presses down upon us in an almost unseen force. To prove this he evacuated
two very heavy large hemispheres, after having placed them together with
a leather seal. This leather seal would certainly have had some thick grease
or fat, possibly beeswax melted into it to provide an airtight seal. With
the use of his newly invented vacuum pump he then evacuated the hemispheres,
which stayed together under the pressure of air outside. Using an increasing
number of horses he then began to try and pull them apart. Horses at that
time were thought to be and recognised as being very strong; they were used
daily in ploughing and working the land, as well as for war horses and transport.
Von Guericke progressed to 16 horses, although I have heard in later discussions
and writings that he was considering using a larger number of horses.
On Saturday 18th March we at Barometer World organised this re-enactment
on the Old Bowling Green at Torrington. Despite being aware of the experiment,
and having seen photographs and a video when it was performed in Germany
previously, this was the first time ever in the United Kingdom that this
experiment took place with 16 horses; it is only seeing the experiment in
the flesh that brings home the tremendous forces involved in holding the
spheres together. With the 16 horses accustomed to daily working on farms,
brought together especially for this occasion, pulling and straining to
pull the hemispheres apart one really gets a feel for this immense weight
of air around us in which we live all the time and in which the daily variations
are indicated on the barometer, which itself indicates the approaching weather
changes. Fortunately on the day the weather was dry. In the morning it was
slightly overcast but lovely and sunny in the afternoon. The pressure was
high at 1035 mb, further ensuring that the hemispheres would be held firmly
together. Very occasionally they will pull apart due to low pressure, particularly
at high altitude and if the horses pull with exceptional force. Before the
main experiment a number of small experiments were conducted with children
pulling on small hemispheres and eighteen men pulling against two horses.
In the afternoon the horses easily overcame the strength of eighteen men.
It was experiments such as these that encouraged early scientists, and indeed
meteorologists to study the air pressure changes and to interpret the wonderful
weather, which fascinates so many of us today. Next time you look at your
barometer try and remember that it is indicating the current pressure but
that normal average pressure is about 15 lb per square inch pressing down.
We are used to this phenomenon and indeed we would suffer greatly if the
pressure reduced. Our whole being depends on this pressure and the air that
we breathe.
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