The slide rule was a vital tool, which as its name implied
Comprised a ruler-shaped device, in which a central slide
Was free to move, from side to side, and so one might prevail
To draw upon the benefits of logarithmic scale.
As once was taught to those at school, in maths (Pure not Applied)
That logs involved addition, for figures multiplied
In formal terms this was expressed as log 'x' plus log 'y'
Equated to their aggregate (defined as log 'xy').
With markings on the slide itself and on the rule "adjoint"
One could divide and multiply, albeit that the "point"
(Defined by system: decimal) was free to "float at will"
Since its correct positioning relied on user skill.
Assisting with the process of rule interpretation
(Essential where the scales compressed their detailed calibration)
A cursor line on background clear could ride across the face
While lugs set into lengthwise grooves ensured it stayed in place.
By way of illustration let's consider two times three
Step one involves the sliding scale on which its "unity"
Is moved until it sits atop the two that's found below
And then back on the scale above we seek the three to show.
It now stands on the number six (our inputs both combined)
Achieved by movement of the slide as values were aligned
And should division be required the process just rehearsed
Will be the same except, of course, the stages are reversed.
Before this text draws to a close and reaches its conclusion
It's notable that other scales appeared in great profusion
Cosine, Tangent, Sine et al (for Trigonometry)
Cube and square roots and log log (to name a further three).
But, sad to say, the slide rule's rule was set to slide away
Replaced by printed circuit boards with LCD display
Which, linked to keyboard entry, meant we waved a fond farewell
To products bearing famous names: like Faber (with Castell).
© Paul Goodman, 2008
Historical Note:
Literary historians will one day derive great interest and no doubt university RAE/REF points from noting that, when first published, this poem had a different last line. It originally read: 'To the products from such makers as Faber & Castell', however an all too astute correspondent with the Society, whose diligence and attention to detail can only be admired, pointed out that this was never a name used by that famous company. Our esteemed poet countered that AW Faber had indeed become Faber-Castell but that he had rules in his personal collection where 'Castell' appears in isolation on the slide, with AW Faber only on the inset of the main body (i.e. under the slide), so he decided that to replace the hyphen of what is now the official corporate logo with an ampersand fell comfortably within the bounds of 'poetic licence'..... however, not to be daunted, he came up with an alternative last line that combines both accuracy and perfect scansion. Now you wouldn't get that with any lesser Society!
Gentleman Jim Bennett. astrolabist from Belfast
Looked at his screen, and was really aghast
For Rete on top
Was having a hop
With Epact, whilst shadow square came in last
© Anthony Turner, 2008
Historical Note:
Anthony Turner wrote limericks about several prominent members of the Scientific Instrument Society; the final ones appeared in the June 2008 Bulletin and he says there will be no more. Jim Bennett is the current Director of the Museum of the History of Science in Oxford. Rete is a specialist electronic mailing list administered by the museum. Epact is a collaborative website featuring scientific instruments of Medieval and Renaissance Europe from museums in Oxford, London, Florence and Leiden. The shadow square or altitude scale, is a feature found on the back of astrolabes and quadrants.
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