Slide rules HOME page COLLECTION 5" RULES
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Make BRL Blundell, UK
Model Type P8

1. In many ways this is a very simple rule. What makes it worth including is that is one of the few rules made of Bakelite.

2. Bakelite, the first synthetic plastic, was invented by a Belgian resident in the U.S.A., Leo Beakeland , in 1907. This material was used for both the stock and the slide covered with stove enamel paint. The earlier models of the same rule have paint only on the front face but tended to warp.

3. This rule was the first slide rule made by Blundell. They had produced a number of different products over the years including felt. During World War II they produced switch-gear for which they used Bakelite. At the end of the war, having an unused stock of Bakelite the decided to use it for slide rules. Although Bakalite had been around for a long time, improvements had been made to the basic formulation which rendered it suitable for machining and less brittle. This is why earlier rules had not been made of that material. Soon after other plastics more suitable for slide rule manufacture became available.

4. The bakelite was almost black in colour. That is why the image of the slide in the back view was scanned against a white background.

Front view
0527-brl-p8-01.jpg (6212 bytes)
Detail - front left
0527-brl-p8-02.jpg (8724 bytes)
Detail - back left
0527-brl-p8-03.jpg (7189 bytes)
Manufacturing date 1947 to 1949 (P. Hopp)
Length 5"
Material Celluloid on Bakelite.
Scales A [B, CI(RC), C] D
Cursor Glass with metal runners.
Hair lines Single line