Slide Rule Workshop Rekenlinialenworkshop

Dutch Circle of Slide Rule Collectors Kring Historische Rekeninstrumenten

This page lists pictures of mysterious slide rules contributed to the online International Slide Rule Workshop.
indicates items discussed during the first workshop in February 2025.
But usually there is no definitive answer to the questions!
If you like to add an answer, or suggest an item for the next discussion, please send a message to @ Deze pagina toont afbeeldingen van mysterieuze rekenlinialen die zijn aangemeld voor de online Internationale Rekenlinialenworkshop.
geeft aan welke items zijn besproken tijdens de eerste workshop in februari 2025.
Maar meestal is er nog geen definitief antwoord op de gestelde vragen!
Als u een antwoord heeft, of een item voor een volgende workshop wil suggereren, stuur dan een mailtje dan naar @

1. Logarex Typ01 Nathan Zeldes
   We know the maker but nothing else – and it is a VERY weird design (look at the back too).
2. The “Pose-Marre” pen slide rule Nathan Zeldes
   We have the “Gebrauchsmuster” but no other information about who manufactured it.
3. The EngPen Nathan Zeldes
   We know really nothing about this pencil slide rule, except for US patent 883800 granted to William Harlow, which describes an instrument that is not completely identical to this one.
   
4. Kawamura's Position Line Calculator” John Mann
   Questions:
   1. Where and when was it made?
   2. Which company made it?
   3. How to use it: what are “h”, “d”, “l” what do the answers mean?
   4. Why are there more scales on this than on the D&P HR1 ?
5. “Zelluglas” slide rule Leo van der Lucht
   Questions:
   1. Has anyone ever seen this slide rule? It makes me suspect that it comes from German-speaking country because of the descriptions on the back
   2. Who made it? “Zelluglas” is not found as information in relation to slide rules.
6. An unknown black disc. Leo van der Lucht
   Questions:
   1. What is this disk for?
   2. How does this disk work?
   3. Can a manufacturer be identified?
7. “HH” Wooden slide rule Chris Hakkaart
   Question:
   1. What is “HH”?
8. Plastic slide rule Chris Hakkaart
   Question:
   1. Any idea?
9. Two slide rules with special figure Chris Hakkaart
   Questions:
   1. What does the special figure mean?
   2. Name?
10. Simple Slide Rule with no name Chris Hakkaart
    Question:
    1. Name?
11. Folded plastic with plastic slide Chris Hakkaart
    Question:
    1. Name?
    2. Purpose of small bulge at each side?
12. D&P slide rule with db, μv and MHz scales. Nikos Velissaris
    It is made of plastic and dated probably around 1935 or 1936.
    Questions:
    1. What is it used for?
    2. When was it made?
13. “Ich Dien” slide rule Peter Hopp
    Arranged by S. Waddington, Barnsley.
    Questions:
    1. ???
14. Nestler slide rule Jean Paul Hild
    
    1. When was it manufactured ?
       Seems to be of SOHO type but I couln'd find other Soho rules from Nestler
    2. Why are the scales deferred ? (see picture)
15. I of C slide rule Jean Paul Hild
    
    1. Who made it ?
    2. Where was it made ?
    3. What did it serve for ?
    4. How does it work ?
    5. What is the purpose of the two windows in the bottom ?
16. German silver slide rule James Bready
    
    1. ???
17. Four-slide slide rule Amy Ackerberg-Hastings
    National Museum of American History, Catalog Number 1999.0068.01
    1. ???
18. Japanese Artillery Simplex Slide Rule Amy Ackerberg-Hastings
    National Museum of American History, Catalog Number 1978.2289.01.
    Note: The PowerHouse Museum link should read https://collection.powerhouse.com.au/object/384855
    1. Maker ?
19. Unknown Soho found in Germany Fred Astren
    
    1. What is this?
20. Metal slide rule marked G. Atkins, London Roberto Pascual
    1. ????