Editing Barometer (section)

==== Wheel barometers ====
A wheel barometer uses a "J" tube sealed at the top of the longer limb.  The shorter limb is open to the atmosphere, and floating on top of the mercury there is a small glass float.  A fine silken thread is attached to the float which passes up over a wheel and then back down to a counterweight (usually protected in another tube).  The wheel turns the point on the front of the barometer.  As atmospheric pressure increases, mercury moves from the short to the long limb, the float falls, and the pointer moves.  When pressure falls, the mercury moves back, lifting the float and turning the dial the other way.<ref>{{cite web|last=Hood|first=Jean|title=Barometers : History, working and styles|date=5 December 2017|url=http://www.jeanhood.co.uk/barometers_history_and_styles_etc.html|access-date=21 June 2020}}</ref>

Around 1810 the wheel barometer, which could be read from a great distance, became the first practical and commercial instrument favoured by farmers and the educated classes in the UK. The face of the barometer was circular with a simple dial pointing to an easily readable scale: "Rain - Change - Dry" with the "Change" at the top centre of the dial. Later models added a barometric scale with finer graduations: "Stormy (28 inches of mercury), Much Rain (28.5), Rain (29), Change (29.5), Fair (30), Set fair (30.5), very dry (31)".

Natalo Aiano is recognised as one of the finest makers of wheel barometers, an early pioneer in a wave of artisanal Italian instrument and barometer makers that were encouraged to emigrate to the UK. He listed as working in Holborn, London {{circa|1785}}–1805.<ref>{{cite web |title=Natalo Aiano |url=https://www.aianos.co.uk/about-us/ |website=About us page |date=22 May 2017 |publisher=C. Aiano & Sons Ltd.}}</ref> From 1770 onwards, a large number of Italians came to England because they were accomplished glass blowers or instrument makers. By 1840 it was fair to say that the Italians dominated the industry in England.<ref>{{cite book |last1=Nicholas |first1=Goodison |title=English barometers 1680–1860 : a history of domestic barometers and their makers and retailers |date=1977 |publisher=Antique Collectors' Club |isbn=978-0902028524 |edition=Rev. and enl.}}</ref>