F.19 Data Sheet MJS-p-0317

Blundell Rules Limited, Pilot Balloon Slide Rule Mark IV-A, 1957-1964

Serial Number or Date Stamp: 480

Country: UK Primary construction material: pl Case included?: box

General Description: Specialty linear slide rule

Length of 1 decade = 7.5 in, and overall scale length = 22.5 in. The largest physical dimension is 24.5 in.

Front Scales: Log Cos Sin [ K Grat/K ] sec2/Tan

Back Scales:

Notes: Used by the U.K. military/meteorologists to compute wind speed at various altitudes using data from sightings of “weather” balloons from ground-based telescopes; special thanks to Laurie,Peter(!),Stephen,Olivia,Arden for getting this to me from Australia

References: JOS V5.2p51 (1996); Jour. Sci. Inst., V5.11 p345 (1928); https://home.csulb.edu/~mbrenner/

Date Acquired: 08/07/2023