(G)  THE HISTORY OF SLIDE RULE INVENTORS:
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1594 JOHN NAPIER invented the logarithms to simplify multiplication
     and division arithmetic. (See also Chapter »Napier's Bones«!)
1620 EDMUND GUNTER used this concept and made logarithmic scales.
     Calculation was performed with the aid of a pair of dividers.
1622 WILLIAM OUGHTRED invented the »Slide Rule« as two linear or
     two circular sliding scales.
1650 EDMUND WINGATE and SETH PARTRIDGE improved the tool to our
     known shape with upper and lower stator and slider in between.
1850 AMEDEE MANNHEIM made a slide rule with a cursor and a useful
     combination of scales: X and X-square pairs on front side;
     sine and tangent scales on the back side of the slider - But
     the slider has to be turned to use these scales on front!
1902 MAX RIETZ modified and enhanced the »System Mannheim« with a
     X-cubic scale and mantissa scale on front and gaps with index
     lines on the back side: Now the slider could be read on the
     back side without turning the slider in the slide rule. 1925
     he added a reciprocal-X scale and scales for small angles.
1934 ALWIN WALTHER in the Technische Hochschule Darmstadt modified
     and enhanced the »System Rietz« for the needs of engineers: A
     Pythagorean scale on front was added. The mantissa scale was
     transfered to the rear long side and the sine and tangent
     scales to the front long side. The back side of the slider was
     now free for the exponential scales. This »System Darmstadt«
     became the base model for all the following improvements...
1936 PHILIP DALTON filed a patent for a FLIGHT COMPUTER: A circular
     slide rule to calculate "True Air Speed", "Altitude Correction",
     "Fuel Consumption", ... In cooperation with the US Army AirForces
     it became the famous  »E-6B«  to calculate also the "Wind Drift".
     "Dalton's Dead Reckoning Computer"  was used in WWII also by the
     US Navy, the British Royal Airforce, and (copied) by the Japanese
     and Germans.  The »E-6B« ( and its modifications ) are still in
     use today in pilot schools and by privat pilots.


(H)  HISTORICAL REMARKS TO SLIDE RULE COMPANIES...
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     ... mainly based on the book of Dieter v.Jezierski »Slide Rules«