• 455 Martinson, Los Angeles
  • 8 (043) 567 - 89 - 30
  • support@email.com
  • ALRO-made ruler unusually with a cursor for analysing ECG printouts of the cardiac Sinus Rhythms
  • Hatters Gauge - for measuring the size of a hat but unusually calibrated in metric & imperial
  • Glovers Rule - for measuring the length of a glove
  • Unusual non-logarithmic squaring desktop QR 41 model by Dennert & Pape (D&P)
  • Colour combinations slide rule for Interior Designers
  • Professor Fuller’s Drum Calculator from 1878 - made by W.F. Stanley
  • Modern Kienzle wristwatch with slide rule bezel calculator
  • Ruxton Multi-Vider drop-lead pencil & slide rule
  • Rare Otis King Model N for Retail & Monetary with white scales (422 & 424) on a black background
  • Darnley’s Rotable Lightning Calculator/Pencil Case
  • Design for this Antenna Radar Beam Pattern Detection slide rule was classified during WWII by UK & US governments - made by Lawrence
  • Makeba Kombinator pencil & slide rule
  • Rare Carbic-made Fischer Calculator
  • Specialist slide rule for a national home cable radio broadcasting system offered in The Netherlands from 1930 to1970
  • Smallest drum (≈ 2.4m) made by LOGA

My collection ....

In 1991, when unpacking a removal box, I came across the long-forgotten slide rule from my student days. I was intrigued - how long have slide rules been around? Soon after a bizarre tongue-in-cheek idea struck me: 
“What else could an (ex)computer man collect but analogue slide rules!”

Slide rules come in all shapes and sizes but most are either:

  • Linear - by far the most common
  • Circular or disc form
  • Drum or cylinder form
  • Tubular
  • Watch (pocket or wristwatch)

They are hard wearing, do not break when dropped and unlike modern day calculators, they do not need batteries! Strictly speaking to be a slide rule it must have at least a pair of Log x or C/D scales. Most items in my collection fit this definition but various slide charts, the odd novel calculating aid and some hybrids have sneaked in!

For enthusiasts or fledgling collectors the excellent online Reference Manual by the Oughtred Society covers all the basics and much more. Or else try An Easy Introduction to the Slide Rule by Isaac Asimov (yes, the SF writer). But if you are just looking for cleaning/restoration tips Eric Marcotte’s or Tom Dilatush’s webpages can help.

My collection is made up of items from many makers but the niche parts are the ♫ acoustic ♫ (yes, they exist!) and the oversized desktop slide rules. Nowadays I have a special interest in models from the two only Dutch slide rule makers ALRO and Systeem Matthijssen alongside slide rules with a quirky or novel use - e.g. for ringing Church bells. The collection has grown to 2000+ slide rules, 200+ slide charts, 40+ Ready Reckoners, 15+ slide adders and 30+ mechanical calculators. Do try one of the adjacent search options to find items of interest.

Every month or so a batch of new items is added but because of the sheer volume it will be ages before the entire collection is uploaded! So check regularly for any NEWS item on the HOME page announcing the latest batch!

My wish list

Sought after models still missing from the collection:
A.W. Faber-Castell8/13, 8/14, 8/15 & 51/88
Addiator GmbHOctadat
AHREND (Wed. J. Ahrend & Zoon)642T, 649, 651, 690, 696, 698, 699 & 701
ALRO (All-Round)101, 10 RL, Beton, Cycloop, GoA, Ha.C/P/Q/V, Ha TEX, Piret, Philips Calendar, Nomographie, Van Leer, Vonderlingenplaat & WeR4
AWF (Ausschuss fuer Wirtschaftliche Fertigung)SR703, SR705-709, & SR754
Controller Calculator200 R
DARGUE Bros. Ltd. / SimplonSub-Ivory SR-1 & SR-4 + Honduras SD10, WR-2A, WR-5 & WR-7
Fearns CalculatorsBarber Shop Harmony Calculator
FowlerNautical, Artillery, Kearns & Mackay
ITAB (Internationaler Tabellenverlag)Multicalor Flachheizkorper & Styropor-Vollwarmeschutz
IWA – F. Riehle GmbH & Co KG15489 Harmonik
Johann Faber180/080, 180/082, 9203, 9204 & 9204
Keuffel & Esser (K&E)4081-3 Braille version
KOSMOSBook: "De Rekenliniaal" - 11th & 12th Editions
L&C Hardtmuth / Classic10" Series III
Lawrence Engineering ServicesS-M (C.V. Ore) & Exposure (MIT)
LOGA Calculator A.G.TF, T150, T300, O2 Calculator, 30 TxC & 75 Terminator
Logomat Rechengeräte1300/1303
NestlerRP 75, Kreisrechner & Disc-O-Lator
S.R.&S.E. (Slide Rule & Scale Eng. Co.)- any -
Systeem Matthijssen- any -
UniqueJunior, Study 500/700/900 & J180/181/182

Search by maker

Search by keyword

Tip: separate keywords (implict AND) by a space or a comma and if needed, limit the search by adding keywords proceeded by a hyphen: e.g.-Faber, -plastic. Phrases in quotes may also be used.

Browse all 1368 items so far loaded from my collection

Note: given the number of items uploaded this page can take a minute or two to load.

Unusual Slide rules for sale or swop (click on the model for details)

A.W. Faber-Castell111/22Business
A.W. Faber-Castell2/82Technical/Log-Log
A.W. Faber-Castell2/83Technical/Log-Log long-scale
A.W. Faber-Castell2/83NTechnical/Log-Log long-scale
A.W. Faber-Castell378Electro
A.W. Faber-Castell62/83Pocket Technical/Log-Log long-scale
AHREND (Wed. J. Ahrend & Zoon)ELECTRO 15Electro
AHREND (Wed. J. Ahrend & Zoon)HOLLANDIA-REKENSTOKEnhanced Mannheim
ALRO (All-Round)100 R (AC-1.04a)Rietz - H
ALRO (All-Round)100 R (AC-1.04b)Rietz - early
ALRO (All-Round)1010 Commercial (AC-1.18)Business long-scale
ALRO (All-Round)200 R (AC-1.05a)Rietz - two-tone paper discs
ALRO (All-Round)200 RL (AC-1.49a)Rietz
ALRO (All-Round)300 D (AC-1.08a)Darmstadt
ALRO (All-Round)600 E (AC-1.19)Electro
ALRO (All-Round)746 De Muiderkring (AC-1.nn)Waistcoat Radio Electronics
ALRO (All-Round)BoB3 (AC-1.nn)Reinforced Concrete - System Dussel
ALRO (All-Round)KLOOS (AC-1.30)Steel Constructions
ALRO (All-Round)MILITAIRE REKENSCHIJF (AC-1.32)Military Terrain Analysis
ALRO (All-Round)MILITARY CALCULATOR (AC-1.nn)Military Terrain Analysis
ALRO (All-Round)PTT DECIBEL (AC-1.42)Radio Electronics
ALRO (All-Round)PTT DECIBEL (AC-1.43)Pocket Radio Electronics
ALRO (All-Round)ST 9-430/2 (AC-1.34a)Military Artillery Range Finding (1 of 2)
ALRO (All-Round)ST 9-430/2 (AC-1.34b)Military Artillery Range Finding (2 of 2)
Blundell Brothers/Rules Ltd. (BRL)644944 / P5284Radiac Nuclear Fission Products poly-slide (2)
Blundell Brothers/Rules Ltd. (BRL)G.2Enhanced Mannheim without Trig scales
Blundell Brothers/Rules Ltd. (BRL)L.4Log-Log
Dennert & Pape (D&P)D 2/28Enhanced Mannheim - early
Dennert & Pape (D&P)S 6/28 (System Rietz)Rietz
ECOBRA (Bayerische Reisszeugfabrik)1461Pocket Rietz
Graphoplex1614School Log-Log C.A.P.
Graphoplex16ooSchool Riez C.A.P. - early & all black
Graphoplex620 d (ver. 1)Rietz
Graphoplex630Geometre Surveying Topography - 400g early
Graphoplex640Electro Log-Log
Heath & Co.Hezzanith Le PatourelCelestial Navigation/Mannheim
Hemmi135Pocket Darmstadt
Hemmi255DElectro Hyperbolic
Nestler0137Pocket Electro two-tone
Nestler11Pocket Enhanced Mannheim
Nestler43Reinforced Concrete - System Hoffmann
NestlerABLMilitary Vehicle Logistics & Supply
NORMA-MechanikMekuria 190Business
William LangleyCarpenter TimberDesktop Coggeshall