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Details of: AHREND (Wed. J. Ahrend & Zoon) - 699 (0905 Commerz)

Type? A generic name (e.g. Rietz) or function/use for specialist models (e.g. Meteorology) for grouping similar models across makers. If not “standard” 25cm linear length, preceded by the form (i.e. Demonstration, Desktop, Pocket, Waistcoat, Keyring, Lilliput or Book) + if needed, qualification to distinguish between versions (e.g. early or late). Business - early
Sort? L/C/D/T/W/X where L=Linear, C=circular, D=Drum, T=tubular, W=watch, X=miscellaneous (i.e. the rest) L
Construction? Basic construction form of the body i.e. Closed/solid frame or Open frame or Duplex or Other Open frame
Material? Basic description: ivory/bone/wood/bakelite/plastic/metal/cardboard or combinations e.g. wood/veneered, wood/painted, etc plastic
Length? Mostly the linear length of the D scale (in cm or inches) excluding any extensions. For circular/watch slide rules it is the diameter but for helical/tubular/drum slide rules it is the overall scale length. For other calculating aids it is the physical length. 25cm
Scales front? Standard (not maker’s) symbols for scales on front face e.g. A = X² (1-100) but § = generic symbol (signum sectiōnis) for any non-standard scale + scales between solidi / / are on the slide(s) whereas scales after vertical line | or after reversed solidus \ are on a straight or bevelled top or bottom side edge cm,%,§ / §,CI,C / D,inch
Scales back? Standard (not maker’s) symbols for scales on back face e.g. S = sine (5° to 90° & 85° to 0°) or sin(x) but § = generic symbol (signum sectiōnis) for any non-standard scale + scales between solidi / / are on the back of slide(s) but scales listed after / / - notation are on another surface e.g. back of stock or inside a lid
Cursor type? Basic description (incl. material) + no. of hairlines, etc on any cursor(s) or alternative to a cursor - e.g. a stylus plastic - 1 off-centre hairline
Condition? Cn where n = 0-6  condition/quality scale where 0 = brand new in box & 6 = broken   C4
Date? YYYY for year(s) of production or an approximation/range of years 1954-1970
Extras? Basic description of any accessories - e.g. case or stand + where relevant, an accreditation for image, etc
Instructions? Details like “on back of rule” and/or language of instruction sheet/booklet - generic or instructions for common layouts usually not listed German (photocopy)
Booklet (PDF)? Downloadable .PDF copy of unusual or uncommon model specific instructions download
Comments ? Any special or noteworthy traits + significant use-related facts + pertinent details of scales/tables in well of stock + any significant tables, etc on the back of the stock

OEM by ARISTO with Aristo-Commerz on front + Ahrend co-branding with model no. in back

In-Out? MM-YYYY / MM-YYYY of the date added/left the collection or <YYYY if exact MM-YYYY no longer known <2000/

All of:  AHREND (Wed. J. Ahrend & Zoon) new search?

ModelType
(P281) Demonstration Rietz
435061 (845 Commerz I) Pocket Business
435064 (89) Pocket Rietz
435660 (P280) Darmstadt-like two-tone
435661 (P281) Rietz-like two-tone
435662 (P283) Technical two-tone
642T Rietz
690 (89 RIETZ ) Pocket Rietz
691 (99 Rietz) Rietz
694 (0968 Studio) Technical/Log-Log
699 (0905 Commerz) Business - early
703 (0970 MultiLog) Technical/Log-Log
74 Pocket Rietz - late
791/7 Diagonal Scale
810 Diagonal Scale
ELECTRO 15 Electro
ELECTRO 654 Electro
HOLLANDIA-REKENSTOK Enhanced Mannheim
NORMAL 650 (Ver. 1) Enhanced Mannheim
NORMAL 650 (Ver. 2) Enhanced Mannheim
RIETZ 652 Rietz