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KEUFFEL & ESSER   N4102   SURVEYOR's   SLIDE RULE
( 20" / 50 cm Scales )

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KEUFFEL & ESSER, Hoboken, NewJersey / USA     SN = 704190      (1950)
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K & E  (1915) ADVERTISEMENT  of the  » 4102 «  SURVEYOR's SLIDE RULE:



R E M A R K S :
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This  » N4102 «  is made of mahogany with scales on celluloid veneer.
The UPPER FRONT  S C A L E  ( over »D« )  IS  U S E R  (!)  M A D E :
It starts with  35'  ...  1°  ...  1°30' ... 



The SR came in a brown leather case.  The CURSOR WAS DETORIETED ...

    

           ... the  BLOCKS  had to be replaced by home-made PVC ones.

Same "CELLULOID DISEASE"  happened also to the  K & E  4081-5  ...
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Celluloid,  first produced in 1872,  was the first used plastic world
wide.  It consists  of a  mix of  cellulose nitrate  &  camphor.  The
plasticizer camphor  is given off  over time  and the nitrate  breaks
up  under  the  influence  of oxygen  & moisture  and  transforms  to
nitric acid.  Both effects  destroy  the material -  and  the acid is
the reason why  the metal of frame  and spring  get brittle  & rusty.

                      Historical Remarks ...
impressum:
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© C.HAMANN     http://public.beuth-hochschule.de/~hamann     07/24/14