Slide Rules & Rulers

[CommanderJameson]

Well, I can't think of a better forum for this post, so here it is.

I've just picked up a number of slide rules and rulers of pre-1960s vintage, that were my father's, and I'm in the process of investigating their provenance and value.

Information on these items is thin on the ground, so I wondered if any PHers had interests in this direction.

One of the slide rules, to give a flavour, is a "RULES, SLIDE T.E.R. NO. 5." which appears to be for determining the impedance of various lengths and gauges of cable, and appears to have been issued by the GPO in 1958, and carries the broadarrow marking.

[CommanderJameson]

Here are some examples of what I've got:

Firstly, a RULES, SLIDE T.E.R. NO. 5.



And two views of a 6-inch wood/bone ruler:





I'm particularly fascinated by the method of construction of the ruler. Surely it would have just been easier to make it from steel?