General Information

Serial #

67/57

Part Number

1

Total Parts

2

AKA

N/A

Patents

N/A

General Description

plastic rule/ brass framed cursors with synthetic substrate for the graticles/ brass knobs

Dimensions

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

Length

62.6 cm

Width

5.8 cm

Height

N/A

Thickness

2.0 cm

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Mathematics

Category

Calculating devices

Sub-Category

N/A

Manufacturer

AKA

Farrow

Country

England

State/Province

Unknown

City

London

Context

Country

United Kingdom

State/Province

Unknown

Period

late 1950's+

Canada

A British made instrument possibly used by the Meteorological Service of Canada, though the specific use there is not known. Part of a large collection of meteorological instruments acquired from the MSC (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.

Function

An instrument used to carry out the computations based on observations (altitude, azimuth and distance) of pilot balloons with radar in order to measure the speed and direction of wind in the upper atmosphere.

Technical

An example of a specialized function slide rule used to make meteorological calculations. It is a typical looking slide rule but with scales only on one side and with scales suited to determining the speed and direction of winds using radar bouncing off pilot balloons. Scales include sine, cosine, height in meters and range in meters and there are 2 cursors. It has a Meteorological Office mark (O stamped over M). The serial number 67/57 is consistent with UK's Air Ministry codes used on air sextants made during WW II and indicates a date of manufacture of 1957. This particular slide rule was designed by the Meteorological Office of the Air Ministry (UK) in 1957. From MSC meteorologist Ken Devine: this appears to be the British slide rule used to compute pilot balloon winds. See Handbook of Meteorological Instruments, Part II, British Met Office, London, 1961 (Ref. 1). Slide rules have been used in various from since the early 17th c soon after John Napier invented logrithmetic tables. Wherever calculations were required that involved logs or trignometric functions, slide rules provided an efficient way to do the computations. Mechanical and electromechanical calculators supplemented slide rules beginning in the 18th c but their expense limited the impact. More models, particularly de Thomas' Arithometer and Curta calculators (ca. 1948) further impacted the scientific use of slide rules but they were not made obsolete until the HP-35 electronic calculator appeared in 1972.

Area Notes

Unknown

Details

Markings

Black lettering on rule reads 'REF. No MET. 10496 M.O. 67/57 MO [logo]', 'RADAR WIND SLIDE RULE MK.1' and 'JAMES FARROW & SON/ LONDON'/ red and black scale markings and lettering reading 'COSINE SCALE', 'HEIGHT IN METRES', 'RANGE IN METRES' and 'SINE SCALE'

Missing

appears complete

Finish

white rule/ gold coloured brass/ colourless transparent parts

Decoration

N/A