Hemmi 80 (?)

I have two almost identical Hemmi slide rules with the following scales

although the scales on the front are not labelled.

Neither rule has a model number on it but one has "No 80/1" on a small paper label on one end of the box.  The other rule could have a similar (or identical) number on its box, but the box has been repaired with tape which covers the ends.

On the first rule LL2 runs from 1.1 to 3.2 and LL3 from 2.4 to 100000.  As usual e is opposite either 1 (LL3) or 10 (LL2) on the D scale.

This second rule has unusual LL2 and LL3 scales.  LL2 has been displaced slightly to the left so that 2.74 is opposite 10 on D (rather that e = 2.72).  LL3 has been displaced rather more to the left so that 3.08 is opposite 1 on D.  LL2 runs from 1.1 to 2.9 and LL3 from 2.9 to 100000.  On the slide there is a line marked W to the right of 10 on C.  It is positioned so that the distance from 1 to W on C is the same as the distance between 2.9 on LL2 and on LL3.

Does anybody know why this second rule has its LL2 and LL3 scales arranged this way? Please send me any information at peter.owen@physics.org

Rule with normal alignment of LL2 and LL3 scales
e (=2.72) on LL3 aligned with 1 on D	e (=2.72) on LL2 aligned with 10 on D
Rule with non-standard alignment of LL2 and LL3 scales
3.08 on LL3 aligned with 1 on D	2.74 on LL2 aligned with 10 on D

10 on C scale aligned with 1 on D scale to show position of W marker. The L and T are marks made by a previous owner.

This page was last updated on 7 February 2000.

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