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Barometer
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The barometer is an instrument for "weighing" air. It works in much the same way as a set of scales: the weight of the mercury column is offset by the pressure of air on a bowl full of mercury. In 1644, Torricelli observed the level of mercury in a tube closed at one end, tipped upside down, and lowered into a bowl of mercury. He observed that the mercury in the tube did not descend all the way. This was because its weight was counter-balanced by the pressure of air on the mercury in the bowl. He also discovered that the height of the mercury column varied, at the same altitude, with changes in temperature. Torricelli's discovery paved the way for the development of the mercury thermometer. At sea level, at 0° C and at a latitude of 45°, the mercury column stays at around 76 cm, whereas at the top of a 2,500-meter mountain, it settles at only 57 cm. In the eighteenth and nineteenth centuries, the barometer underwent many design changes that made it more sensitive, easier to read, and less cumbersome. Toward 1850, the international community adopted aneroid barometers, which are compact and easy to carry.

Objects
Barometer

Barometer

Inv. 1134
Maker unknown, late 18th cent.

Barometer

Barometer

Inv. 1153
Maker unknown, first half 19th cent.

Barometer

Barometer

Inv. 1143
Maker unknown, first half 19th cent.

Barometer tube

Barometer tube

Inv. 114
Maker unknown, Florence, mid-17th cent.

Cecchi balance barometer

Cecchi balance barometer

Inv. 3816
Niccolò Masini, Florence, ca. 1860

Cistern barometer

Cistern barometer

Inv. 1147
Edward Nairne, London, ca. 1770

Cistern barometer

Cistern barometer

Inv. 3707
Nairne & Blunt firm, London, ca. 1780

Cistern barometer

Cistern barometer

Inv. 1161
Maker unknown, second half 19th cent.

Cistern barometer

Cistern barometer

Inv. 1148
Antonio Matteucci, Siena, ca. 1850

De Luc barometer

De Luc barometer

Inv. 1150
Maker unknown, ca. 1760

De Luc barometer

De Luc barometer

Inv. 1556
Maker unknown, late 18th cent.

Double barometer

Double barometer

Inv. 1155
Maker unknown, Italian, second half 18th cent.

Pillar barometer

Pillar barometer

Inv. 1135
Daniel Quare, London, early 18th cent.

Pillar barometer

Pillar barometer

Inv. 1136
Daniel Quare, London, early 18th cent.

Pocket aneroid barometer

Pocket aneroid barometer

Inv. 3659
Giustino Paggi, Florence, ca. 1880

Portable barometer

Portable barometer

Inv. 1131
Galgano Gori, Florence, 1846

Portable barometer

Portable barometer

Inv. 1146
Maker unknown, first half 19th cent.

Registering barometer

Registering barometer

Inv. 1163
Felice Fontana, Italian, late 18th cent.

Siphon and cistern barometer

Siphon and cistern barometer

Inv. 1132
Maker unknown, mid-19th cent.

Siphon barometer

Siphon barometer

Inv. 1141
Giovanni Domenico Tamburini, early 18th cent.

Siphon barometer

Siphon barometer

Inv. 1144
Deleuil firm, Paris, ca. 1850

Siphon barometer

Siphon barometer

Inv. 1142
Giovanni Domenico Tamburini [attr.], early 18th cent.

Siphon barometer

Siphon barometer

Inv. 3627
Giovanni Domenico Tamburini, early 18th cent.

Stereometric barometer

Stereometric barometer

Inv. 1137
Maker unknown, late 18th cent.

Stick barometer

Stick barometer

Inv. 697
Maker unknown, late 18th cent.

Wheel barometer

Wheel barometer

Inv. 1139
Maker unknown, Italian, late 18th cent.

Wheel barometer

Wheel barometer

Inv. 1140
Santino Donegani, Italian, late 18th cent.