Where possible the generic name preceded by the form if not 25cm/10” linear - e.g. Pocket Enhanced Mannheim. For specialty types, often supplemented by its use. Sometimes a suffix is also added to distinguish between versions of the same model.
||Boiler effeciency (150-250 lbs/inch) & energy costs|
L/C/D/T/W/X where L=Linear, C=circular, D=Drum, T=tubular, W=watch, X=miscellaneous (i.e. the rest)
Basic construction form of the body i.e. Closed/solid frame or Open frame or Duplex or Other
Basic description: ivory/bone/wood/bakelite/plastic/metal/cardboard or combinations e.g. wood/veneered, wood/painted, etc
||wood/paper covered by clear plastic|
Mostly length in cm or ” (inches) of the D scale but excluding any scale extensions. But for circular or watch slide rules it is the diameter & for tubular or drum slide rules it is the overall linear scale length. For other mechanical aids it is the physical length.
Mostly standardised (not maker’s) symbols for scales on front of stock e.g. A = X² (1-100) but § = generic symbol for any non-standard scale. Scales between solidi (/ /) are on the slide(s) whereas a vertical line ( | ) or reversed solidus ( \ ) + a symbol denotes scale(s) on a straight or bevelled edge.
||§,§ / §,oF,§,§ / §,%|
Mostly standardised (not maker’s) symbols for scales on back of stock e.g. S = sine (5° to 90° & 85° to 0°) or sin(x) but § = generic symbol for any non-standard scale. Scales between solidi (/ /) are on the back of the slide(s).
Basic description (incl. material) + no. of hairlines, etc on any cursor(s) or alternative to a cursor - e.g. a stylus
||simple folded celluloid cursor with circular cut outs.|
Cn where n = 0-6 based on Herman van Herwijnen’s condition/quality scale
YYYY for year(s) of production or an approximation/range
Basic description of any accessories - e.g. case or stand + where relevant, an accreditation for image, etc
||black "mottled skin" stiff cardboard case|
Details like “on back of rule” and/or language of instruction sheet/booklet - generic or instructions for common layouts usually not listed
||Printed on the back: TO OBTAIN DATA NECESSARY TO USE THIS RULE INSTAL ELECTROFLO METERS AND TEMPERATURE MEASURING INSTRUMENTS + 4-page leaflet|
Downloadable .PDF copy of unusual or uncommon model specific instructions
| 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
© H.W. Healy 1923 - pinned construction suggests OEM rule by Unique or Hardtmuth
MM-YYYY / MM-YYYY of the date added/left the collection or <YYYY if exact MM-YYYY no longer known