F.105 Data Sheet MJS-p-0325

Halden, Calculex, c.1918

Serial Number or Date Stamp:

Country: UK Primary construction material: ss Case included?: yes

General Description: Basic circular polyphase simple pocket watch style slide rule

Length of 1 decade = 6.3 in, and overall scale length = 6.3 in. The largest physical dimension is 2.5 in.

Front Scales: L D [ C R1 R2 ]

Back Scales: S D [ CI RI33 RI32 RI31 ]

Notes: Halden’s Calculex Circular Slide Rule, earlier version type 3b, beveled glass, single screw; Made in Manchester, England by Joseph Halden; folded leather case and instruction book

References: JOS 6.2p40 (1997), JOS 8.2p45 (1999); Peter Hopp, Pocket-Watch Slide Rules, Astragal Presss (2011)

Date Acquired: 11/13/2023