Barometer and Thermometer
Accession Number: 2012.ihpst.17
The instrument is mounted on a vertical wood backing, and is a black enameled metal pole with a mercury capsule towards the bottom. In approximately the middle of the pole, there is a brass thermometer, and at the top, a metal barometer. The mercury capsule is a short glass cylinder held closed by brass screws that go from the top to the bottom. There is a white rectangle behind it in the wood to make the level of the mercury more visible. The thermometer has centigrade and Fahrenheit scales, and the barometer gives measurements in both centimetres and inches. The barometer is a tall cylinder of grey metal with a slit in the front though whith the mercury level can be seen. The moveable precision scale on the barometer is adjusted by means of a large brass screw below the barometer. There is another white rectangle in the wood backing behind the barometer to make the level of the mercury more visible.
Backing: Wood. Apparatus: Metal, Brass, Glass, Mercury
Thermometer: ‘CENTIGRADE’, temperature scale: ‘-20 – 50’; ‘FAHRENHEIT’, temperature scale: ‘0 – 120’.
Barometer: Engraved arrow with an ‘N’ in the middle; ‘NO. 7322’; ‘BAIRD & TATLOCK (LONDON) LTD’; barometric scale: on the left, in cm: ’68-84′; on the right, in in: ’27-33); on moveable calibration between the two: ’25-100′ on left, ‘1-5’ on right
Dimensions (cm): Height = 110; Width = 13; Depth = 10
Function: To tell temperature and pressure
The brass screws holding the mercury capsule together are oxidised, and the brass facing of the thermomter is spotted and discoloured in places. The screws at the very top and bottom that hold the instrument to the wood backing are very oxidised and rusted, and the glass on the mercury capsule, barometer casing, and white backing in the wood is dusty.
Manufacturer: Baird & Tatlock
Date of Manufacture: c. 1912
Provenance: Used by Charles Cross at Canada Packers
This instrument appears as entry number 7995 in a 1912 Baird & Tatlock trade catalog housed in the Smithsonian Libraries. “Price List of Apparatus for Experiments in Practical Physics manufactured and sold by Baird & Tatlock,” London: 1912.
According to the Baird & Tatlock catalog, this instrument originally sold for 10 pounds. It was used by Charles Cross (MSc in Chemistry, University of Toronto, 1952) to measure the pressure of headspace gas of cans in the 1980s while working at Canada Packers. The barometer was in possession of Canada Packers since at least 1953 when Cross began working there and was retained by Cross upon his retirement in 1990. The barometer initially came in a box with a front glass door, although this box was eventually discarded by Canada Packers. Although old for its time, Cross appreciated the barometer’s high degree of precision (it measures to a tenth of a millimeter of mercury).