A generic name (e.g. Rietz) or function/use for specialist models (e.g. Meteorology) for grouping similar models across makers. If not the “standard” 25cm linear length, preceded by the form (i.e. Demonstration, Desktop, Pocket, Waistcoat, Lilliput or Book) & when needed, a suffix to distinguish between versions (e.g. early or late).
||Boiler Efficiency & 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 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.
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
||§,§ / §,oF,§,§ / §,%|
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
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 condition/quality scale where 0 = brand new in box & 6 = broken
YYYY for year(s) of production or an approximation/range of years
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
© design by H.W. Healy 1923 to optimise efficiency of commercial bopiels ((150-250 lbs/inch) + form & pinned construction suggests OEM rule by L&C Hardtmuth for London-based Electroflo Meters Co.
MM-YYYY / MM-YYYY of the date added/left the collection or <YYYY if exact MM-YYYY no longer known