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    Wasting Away in Keuffel & Esser-ville
    From: Hewitt Schlereth
    Date: 2009 Jul 21, 09:47 -0700

    As part an eBay purchase of a K&E slide rule case which I wanted
    because it had the bulge for a magnifier, I got a 4090-3 rule. When I
    looked at the rule, I saw it's stator had Tangent, Sine (called S2)
    and ST (called S1). Its slide, though, only had [CF, CIF. CI, D] on
    the front and [B, K, CI] on the back.
    I wondered if a slide from one of my other rules with T, ST, S would
    fit this 4090. Turned out the slide from a 4070-3 [B, T, ST, S] did.
    I've found this saves steps in doing sine/cosine Hc and Az because
    it's not necessary to zero the slide at the beginning and end of each
    string of calculations.
    The problem I've had is not to look at the Tangent scale instead of
    the Sine scale(s). As you can see from the attached, the stator's T
    scale is directly under the slide's S scale, so my eye tends to fall
    on the T scale first thing.
    I'm now experimenting with various highlighters (on another really
    beat-up rule) to see if highlighting either the Tangent or Sine 2 scale
    will help avoid this.
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