• 455 Martinson, Los Angeles
  • 8 (043) 567 - 89 - 30
  • support@email.com
  • Pocket Octal/Hexadecimal calculator for computer programmers
  • Mystery Dennert & Pape Desktop “Quadrat-Rechenscheiber”
  • Post 1824 Dring & Fage Gauging Rule
  • Darnley’s Rotable Lightning Calculator/Pencil Case
  • Lawrence Antenna (classified in WWII)
  • Makeba Kombinator pencil & slide rule
  • Rare Carbic-made Fischer Calculator
  • For calculating in Twaddells !!
  • PTT rule for Cable Radio (Signal Loss/dB)
  • Smallest drum (≈ 2.4m) made by LOGA

A man must have a hobby….


This non-commercial website was a 60th birthday present from Ros. The name stems from another family member - our daughter Siân. As a teenager she often told her friends: “My Dad? Oh, he collects expensive sticks of wood!”

When the latest PC/tablet is out-of-date in 6 months it may come as a surprise that the Englishman in the image, the Rev. William Oughtred (1575-1660), invented a calculator around 1621 that would be in continual daily use for nigh on the next 400 years. My hobby is collecting and writing about this analogue calculating wonder - the SLIDE RULE.

This site is a virtual “display cabinet” for my collection (as it gets uploaded) of
slide rules and the odd mechanical calculating aid plus a “bookshelf” for my published articles - enjoy browsing.

The history - how it all began ....


To learn more about the history of this remarkable calculating wonder check out the “Slide Rule History” by the Oughtred Society or my 2-page summary (in Dutch!).

Anyone needing a “memory jogger” or is just intrigued how such analogue calculators of the past worked, the International Slide Rule Museum has a richly illustrated “How to use …” guide. Afterwards try doing a few trial calculations with Derek Ross’ online simulation of a Pickett N909-ES slide rule. Thinking of starting your own collection? Then the Oughtred Society’s Beginner’s Guide to Collecting Slide Rules is a great place to start.

Educators looking for maths related inspiration & teaching aids/material need look no further than Nicola Marras’ website. But if just looking for reference books on slide rules try one of these: MyList 1 or MyList 2 .

Latest additions


Slide Rules

Unknown, MAGIC - BRAIN CALCULATOR, Slide Adder - silver/red, X, Other, metal & plastic

news - So far 731 rules are loaded from my collection

08 September 2017

IM2017 Kicks Off in TWO WEEKS

A year in the planning has paid off. Over 50 attendees have registered for the 23rd International Meeting of Collectors & Researchers of Slide Rules & Related Historic Computing Instruments. We will meet up in Bonn, Germany – click here for the conference programme.

29 August 2017


Check out the 40-odd recently uploaded slide rules all made by French makers. Examples from 8 different makers can now be browsed – from the super rare Calculimetre by Emil David, to the test set by Henri Morin, to the colourful and “very French” modern models of perhaps the best known French maker: Graphoplex.

11 March 2017


Site remodelled & restyled to make it “technology neutral”. It should display optimally on any type of h/w device (incl. tablets & smartphones) or browser. Also the restyled search options work faster & more intuitive.

Please tell me what you think ....

02 February 2017


Recently uploaded, the only slide rule conceived so vital to the WWII effort that the UK & US governments had it classified.

25 January 2017

Unexpected Post!

Many thanks to whoever anonymously sent me a pocket ”SpeedyReady Reckoner from the UK (postmarked: South Midlands).

17 January 2017

A New Year, new opportunities

Rod Lovett’s search engines are unmissable tools. Have you tried the two new options added late last year: (i) Long Scale Rules & (ii) Hyperbolic Archive ?

28 October 2016

Have I Got News For You!

The UKSRC Slide Rule Gazette was the guest publication on British television’s highly acclaimed weekly satirical comical news quizz HIGNFY - see the You Tube clip.

My wish list

Sought after slide rules still missing from the collection:
A.W. Faber-Castell4/60, 4/92, 8/13, 8/14, 8/15 & 8/168
Addiator GmbHOctadat
AlroCobol Analyser, Ha Tex & Truck Tyres
Blundell Harling Ltd. (BH)P4463 Holophane Illuminance Calculator
Dargue Brothers Ltd / SimplonSD10 Duplex + any sub-ivory models
Engineering Instruments Inc.Either circular “vinylite” model
Fearns CalculatorsBarber Shop Harmony Calculator
Graphoplex6245 & 6250
InglisFLASH: Pricing, Photographic Exposure, Stock Exchange, Foreign Money, Paper Trades & Health Insurance
IWA15489 Harmonik
KingsonAddiator (combined slide rule & slide adder)
L&C Hardtmuth / Classic10" Series III
Lawrence Engineering ServicesS-M (C.V. Ore) & Exposure (MIT)
NestlerCursor (runner) for 342 (50cm) & 24b (100cm)
Slide Rule and Scale Engineering Co.- any -
UniqueNorman, Perfectus, Dial, Pioneer Long Scale & Junior