First time poster here!

I've been thinking about the survival rates are for mechanical calculators in general, and Curtas in particular. I suspect that the survival rate for large electro-mechanical desktop calculators (e.g. Friden and Marchant) is very low (less than one per-cent), and that the survival rate for hand-cranked desktop machines is a little higher (but probably still only one or two per-cent).

However, I strongly suspect that the survival rates for Curtas is much higher. We obviously have the machines on the List of Curtas, but this is clearly a subset of Curtas 'in the wild' - my two aren't on it!

So, what it boils down to is the question: How many Curtas aren't on the list? Twice as many? Ten times as many?

The list contains about 1250 Curtas out of a total production of about 140000 - roughly 1 per-cent. So how many really survive? 5 per-cent? 50 per-cent?

Any thoughts?

Kindest Regards
John Scriven (UK)

Hi John
Interesting question ... and difficult to find the real numbers.

From my sources I would estimate as following:
- 4% to 5% recorded in different lists and publications on the web (not all public), most of them are traded in the last 10 years
- 0.5% to 1% are are traded each year
- maybe another 3% to 4% are waiting to discover...

So maybe 10000 to 15000 units survived

murff wrote:

- maybe another 3% to 4% are waiting to discover...

My guess would be higher. I suspect that since Curta's are so well made, that no more than 25% would have been worn out and discarded by hardcore users. Another 25% would have been discarded by relatives of a deceased Curta owner who didn't recognize it's value. That leaves 50% waiting to discover, and fortunately with their protective canister, Curtas can wait in a box in a basement for a long, long time. But on the other hand, unfortunately once they are finally pulled out of their hiding spots they may also be discarded by future relatives even more out of touch with mechanical objects than the direct descendants of deceased Curta owners. So perhaps in the long run, the final count of survivors may still end up close to murff's estimate.