Category Archives: News

The three Curtas at the Scientific Artist

A very nice family from Kent brought me the missing Curta for my collection of mint conidition calculators.  The grey Type II on the right is the latest acquisition for the Scientific Artist and sits proudly next to the early Type I in the centre and the early (black) Type II on the far left.  A Difference Engine for the pocket!  No batteries required and 15-digits of precision, it could still outperform the early electronic calculators in accuracy – how cool is that?

Where did I first come across the Curta calculator?

I am pretty sure the first time I saw a picture of the Curta calculator, and therefore became aware of its existence, was when I saw the advert for one in the Scientific American magazine.  I would have been around 16 or so, that means around 1970.  Curiously, 1970 also heralds the demise of the Curta calculator as this is around the time when the first four function electronic calculators made their appearance.  The Curtas looked very interesting to me even back in 1970, mainly because at school we were working with slide rules and therefore had far fewer significant digits at our disposal when performing numerical calculations.  Also, although interesting, they were way outside my budget range as a 16 year old school kid with no job or income, so the Curta was just a very interesting curiosity.

I enrolled for Maths, Physics and Chemistry at “A”-level and we continued to use the slide-rule for numerical calculations, along with log tables (remember them?)  The super-trendy amongst us with rich parents had cylindrical slide rules, where the standard linear slide rule is “rolled around” a cylinder giving a longer effective length to the rule, and therefore the possibility of calculating to more significant digits.  But none of us had a Curta – no other pupil that is, but the teacher for the Pure Maths part of the “A”-level course DID have a Curta calculator, and very proud of it he was too.  He pulled his Curta (I’m pretty sure it was a Type I) from a soft fabric pouch and showed it to us from a distance of several feet, cradling it in both hads for safety.  I remember the feeling of awe being in the presence of this incredible machine.  Clearly this brief moment in time stuck with me for the intervening 42 years and I now find myself in the extremely pleasant position of being able to afford to buy the toys that I could never afford as a kid – the Curta being one such beautiful toy.  I now have superb examples of both the Type I and the Type II Curta calculator, both in pristine condition.

Although I am a William Gibson fan, and read Pattern Recognition some while back, I do not (consciously) recall the Curta calculator even making an appearance in the book (which it most certainly does).  However, the unconscious is a strange and powerful beast, so although I cannot consciously remember reading about the Curta in Pattern Recognition, I am pretty certain my subconscious didn’t miss it, and this has driven my recent resurgence of interest into this most amazing precision engineering achievement 🙂  Thank you Curt Herzstark for creating such happiness with your incredible invention.


The near mint condition Type I Curta calculator, August 1956 vintage, has arrived at last.

The Type I Curta calculator I ordered from the States 2 weeks ago has finally arrived after languishing for a week in U.K. Customs.  Still, it is now with me at long last, and what a real beauty it is.  The description on E-Bay said “super clean”, personally I would have said “near mint” condition.  I really don’t think this Curta has ever been used!!  Already tested it out of course, and it purrs away nicely 🙂 🙂

More on the Curta calculator

What’s really nice about the Curta is that by thinking about the maths problem you want to solve in a logical manner you can minimise the number of handle rotations to calculate the answer.  So for example, finding the answer to 9×9, 99×99, 999×999, 9999×9999, 99999×99999, 999999×999999, or 9999999×9999999 all only take two handle rotations to get to the answer.  But it gets even better than that.  The Curta’s reign as calculator supremo of course came to an end with the advent of the electronic pocket calculator, but now look again at that last calculation in the set above.  The answer the Curta (Type II) gave me to 9999999×9999999 was 99999980000001 which as you note is a 14-digit number.  Now go and check on my (not inexpensive all-singing and dancing) electronic calculator and what happens?  Can’t supply me with all the significant digits can it!  Gives me 9.999998E+13 as an answer – not as accurate as the Curta!  WOW!  Actually have to go to the computer and run Mathematica to get the full run of significant digits – so there you go.  O.K. so my electronic calculator can give me square roots, trig functions, and all the other fancy stuff at the press of a button – but my pocket difference engine can supply me with more significant digits in two handle rotations.  Just how cool is that?