The Curta.org Bulletin Board

[Jim]

It's occurred to me that the only way of dating Curtas accurately is from dated documentation (receipts, guarantees, etc) accompanying the machines. I've made a start on this using data from eBay sales, and it looks encouraging. What I need is more data!
If anyone has paperwork which dates their Curta accurately, I'd be very grateful to hear about it and use it to refine the so-far-nonexistent-but-potentially-wonderfully-accurate Walpole algorithm.
Thanks!
Jim

[jc428]

I also noticed that in one recent eBay auction, there was a guarantee with a date. Funny, the same thought came to mind that this might be a way to more accurately gauge the manufacture date of the units.

However, reality soon set in. First, it appears that paper documentation accompanying the Curtas is rarer and even harder to find that the calculators themselves. No doubt receipts and guarantees are the first items to be lost or misplaced. Second and perhaps more important, receipts and guarantees are a good indication of when the units were sold. I suspect that the actual manufacture date preceded the sale by months, perhaps tens of months.

[Jim]

Well, yes - of course they're rare. That's why I'm appealing on this post! In several years of watching (and buying) Curtas on eBay, I've only seen ten dated documents - five type I and five type II. When dates are plotted against serial number, they give nice straight lines, which makes me think that it's worth trying this method. And yes again - the machines were probably sold up to a year after manufacture, but that still gives a better estimate than that based on assumed production rates. I'll carry on with collecting data, and when there's enough to be fairly confident about the results, I'll put my findings here.

[David Robinson]

I was much heartened to read of your sensible approach, but have not found any invoices or guarantees linked to Curtas. I

Yet it seems to me that type I machines which actually state "type I" before their serial number could only have been produced after the introduction of the type II, said to have been in 1954. The earliest such machine I know of is that of a member of this forum, who has machine number 8419. Does anyone know of any smaller number type I which states 'type I'?

The point of this post is that if these assumptions are true then both algorithms used to calculate date on vcalc.net overstate production figures for the early years, so underestimate production years for the earlier machines.
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David Robinson

[Pete]

My 8335 bears the same "Type 1" notation you refer to here.

I like the theory, but I'm not sure the reality was as neat as that.
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Cheers, Pete

[Steve W.]

My Type II came with three books, a clipped add from a magazine AND a dated sales and import receipt.

The receipt is from N.H. Seward 457-459 Bourke Street, Melbourne
Sold to was in Hamilton NY (has full name and address)

Date on receipt is 7-12-61
Serial number is 514971

[Vincent]

Info taken from eBay auction #: 400206046325 on March 29th 2011
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Vincent

[Pete]

[Peter Johnson]

Robert Cailliau, a one-time colleague of Tim Berners-Lee, has a grey Model II with a plastic crank shown on his website. It is number 532235 (anyone collecting symmetrical numbers?) purchased April, 1968. I also saw a Model II for sale on eBay a while back, with the number 522803, sale date 20 February 1964. These two sightings made me think about the date of mine, as I have 534282, which has a calculated date of April, 1962. Mine is of French origin, the same as Robert Cailliau's. I am now kicking myself as I didn't record where the eBay machine was sold.

Peter Johnson
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PeteJ

[Pete]

34649, for sale on Ebay right now, quote from seller, "The guarantee was dated 3 September 1957 and is from London Office Machines Ltd". Seller notes some dating methods put her machine as 1952 production but...anyway, another piece of the puzzle. HT to ebay seller, thanks!
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Cheers, Pete

[David Robinson]

Interesting additional information!

The date of this guarantee and number fit almost too neatly on the straight line N = 3400(y - 1947) which seems to apply quite well between 1955 and 1969.
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David Robinson

[Pete]

That was quick, I thought I was the only one skiving off work early today but of course you've already had dinner over in the land of GMT!

Yes, you'd think Contina would have normalized production after eight years of selling these, but absent information from the factory (which I fear will never come to light) we're all just guessing. Oh well, by the time I'm old and grey these minor discrepancies will be less important. We need more input, but from whom? Jack has given us some useful clues but we need Hans-Rudolf Roshard to chime in as well - and perhaps the Italian company has something to add.
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Cheers, Pete

[Peter Johnson]

There are a couple on ebay at the moment: Type II, 557687, bought "early 70s"; and one described as Model I, 536707 purchased 21 February, 1967. This buyer has the invoice. However, the machine looks grey to me!

Peter Johnson
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PeteJ

[David Robinson]

It is interesting that of those I can find on eBay at present two early Type IIs (500 225 and 508 429) do not state type II on their baseplates, but a later Type II (518 679) (and later ones) do. Was there ever a time when Type Is were manufactured stating Type I on their baseplate, while Type IIs were manufactured without giving their type?
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David Robinson

[Peter Johnson]

Model 2 up for auction, serial number 524854, sold in USA January (?) 1963.
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PeteJ