Slide rule Model IV.A, 1915
- Inventor
- UK Meteorological Office
- Invention date
- 1915
- Manufacturing date
- Between 1957 and 1964
- Manufacturing location
- United Kingdom
- Manufacturer
- B.R.L. Blundell Rules, Ltd.
- Dimensions
- L 62 W 6 H 1
- Reference Number
- BR
History and Functionality
This rule, designed by the UK Meteorological Office, was used by meteorologists and some military units to determine the ascending wind speed from information provided by a pilot balloon filled with hydrogen or helium.
The position of the pilot balloon is followed by one or two theodolites at one or two minute intervals. The slide rule is used to convert the azimuth and altitude data into speed and wind direction.
From 1915, six different models were built by the Meteorological Office. The last one was produced at the end of 1960.
It should be noted that this rule has sliders to specifically address different data (altitude, azimuth, graticule). The first model was made of wood, the following ones plexiglass.
