General Information

Serial #

361/57

Part Number

2

Total Parts

2

AKA

N/A

Patents

N/A

General Description

non-ferrous metal base, frame, aneroid, spring, bimetal, pen and arm, clock and drum, parts/ plastic cover

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

36.5 cm

Width

16.5 cm

Height

23.6 cm

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Meteorology

Category

Atmospheric pressure measurement

Sub-Category

N/A

Manufacturer

AKA

Environment CA

Country

Canada

State/Province

Unknown

City

Unknown

Context

Country

Canada

State/Province

Unknown

Period

late 1950's +

Canada

An example of a type of barograph designed and built by MSC in the late 1950's and used to measure atmospheric pressure at observing stations across Canada. This specimen was used in the Calibration laboratory at MSC's Toronto headquarters. The MSC Type B barograph was developed between 1952 and 1957 and first appears in M.S.C. literature in the 1957 manual ‘Barographs'(Ref. 1) and the 1958 ‘Vocabulary of Instruments' (Ref. 2) as well as the 1961 and 1965 instrument lists (Refs. 3-4). The Meteorological Branch became the Atmospheric Environment Service in 1971. Part of a large collection of meteorological instruments acquired from the Meteorological Service of Canada (previously Atmospheric Environment Service) by the CSTM since 1967. MSC is the government agency responsible for collecting and disseminating meteorological data and forecasts in Canada. It was founded in 1871 in Toronto where it is still headquartered. The MSC was originally on the University of Toronto downtown campus but moved to Downsview in 1971 on land owned by UofT. The headquarters houses laboratories, research facilities and calibration and instrument maintenance facilities (now largely contracted out).

Function

An instrument that measures and records atmospheric pressure through its effect on an aneroid, a metal chamber partially evacuated of air.

Technical

The first barograph to be designed and built in the MSC workshops was the Type A, which was developed in 1940 (1987.0528-1987.0539). The late 1950's Type B was designed to overcome some of problems with assembly and calibration of the Type A. Like its predecessor,, the M..S.C. Barograph Type B is characterized by the use of a large aneroid in order to overcome friction of the moving parts and provide greater control of the pen arm, allowing recording of smaller fluctuations in pressure. Type B barographs have an external spring and bi-metallic compensation for temperature. Compensation for temperature changes which would affect the aneroid is made by the insertion of a bi-metal strip into the aneroid-pen linkage so that when the temperature does change, the bi-metal bends and its displacement compensates for the displacement caused by the weakening of the spring. This instrument has a metal aneroid and a strong external spring. A bearing is attached to the post extending from the bellows top and the spring's lower end is connected to the bearing. The spring's upper end is attached to a lever controlled a head screw to form the zero adjustment mechanism. The adjustable link on the bellows post leads through a series of levers and links to the pen arm; the bimetallic strip that provides temperature compensation is part of that system. The adjustable link contains pin holes to allow the barometer to be set for different altitudes. As in the Type A barograph, the clock turns the drum around completely once every 78 hours and a three day chart is used. The Type B has a plastic case with a top hinged at its base to reduce damage during shipping and facilitate access for cleaning and maintenance (Ref. 1).

Area Notes

Unknown

Details

Markings

red lettering on frame top reads ‘M.S.C. Type B/ 361/57'

Missing

pen, clock and drum

Finish

glossy green painted base and frame/ plated aneroid, spring, pen arm, bimetal, parts/ brushed chart drum, parts

Decoration

N/A