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.
Inv. 1134
Maker unknown, late 18th cent.
Inv. 1153
Maker unknown, first half 19th cent.
Inv. 1143
Maker unknown, first half 19th cent.
Inv. 114
Maker unknown, Florence, mid-17th cent.
Inv. 3816
Niccolò Masini, Florence, ca. 1860
Inv. 1147
Edward Nairne, London, ca. 1770
Inv. 3707
Nairne & Blunt firm, London, ca. 1780
Inv. 1161
Maker unknown, second half 19th cent.
Inv. 1148
Antonio Matteucci, Siena, ca. 1850
Inv. 1150
Maker unknown, ca. 1760
Inv. 1556
Maker unknown, late 18th cent.
Inv. 1155
Maker unknown, Italian, second half 18th cent.
Inv. 1135
Daniel Quare, London, early 18th cent.
Inv. 1136
Daniel Quare, London, early 18th cent.
Inv. 3659
Giustino Paggi, Florence, ca. 1880
Inv. 1131
Galgano Gori, Florence, 1846
Inv. 1146
Maker unknown, first half 19th cent.
Inv. 1163
Felice Fontana, Italian, late 18th cent.
Inv. 1132
Maker unknown, mid-19th cent.
Inv. 1141
Giovanni Domenico Tamburini, early 18th cent.
Inv. 1144
Deleuil firm, Paris, ca. 1850
Inv. 1142
Giovanni Domenico Tamburini [attr.], early 18th cent.
Inv. 3627
Giovanni Domenico Tamburini, early 18th cent.
Inv. 1137
Maker unknown, late 18th cent.
Inv. 697
Maker unknown, late 18th cent.
Inv. 1139
Maker unknown, Italian, late 18th cent.
Inv. 1140
Santino Donegani, Italian, late 18th cent.