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That Strange Calculator Again

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Nigel Graham 211/01/2022 12:18:43
2009 forum posts
27 photos

Remember this?

strange calculator.jpg

A year after it defied all our attempts to define what it does, I have tested my thought it was used in designing musical-instruments, in particular organs (pipe dimensions and proportions).

So I enquired of Harrison & Harrison, one of the leaders in that highly-specialised field. I have had a very pleasant reply from their Technical Cor-ordinator, Owen Woods, CEng, MIMechE. He admitted not knowing what it is despite asking around, it appears not connected with organ building, and he would be interested to know its real use too!

I thanked him, saying I would report back here and suggesting our members might as I did, enjoy their "virtual tour" of the company and its work:

Their site shows not just some explanation of how pipe-organs work, and the company's own projects; but just how much top-flight craftsmanship is involved in building and maintaining them.

KWIL11/01/2022 15:09:15
3549 forum posts
70 photos

Very addictive to watch

Neil Wyatt11/01/2022 15:35:36
18990 forum posts
734 photos
80 articles

A sort of 20th Century Antikythera mechanism.

Is it worth asking the Science Museum and the NPL for ideas?


Ady111/01/2022 16:00:25
5065 forum posts
734 photos

A knitting or yarn calculator? Textiles, stitches per inch bla?

Nigel Graham 211/01/2022 16:15:25
2009 forum posts
27 photos

The numbers don't seem to have any astronomical or calendar meaning but textiles / knitting...?

I can't imagine what scientific or engineering measurements would use them so the NPL might be just as puzzled.

I never knew my maternal Grandad as he died when I was very young, but I gather he was a "lace designer" - not of the fabirc itself but of the cam-drives on the looms that wove the patterns. A complex process... Perhaps this thing might have had something to do with setting pattern-weaving or knitting machinery? I know someone I could ask though her knowing is a very long shot.


Just come back to add by "edit post", having asked as such, by e-posts both to my friend and to a textiles museum.


Edited By Nigel Graham 2 on 11/01/2022 16:50:45

Dave S11/01/2022 16:51:51
361 forum posts
90 photos

I missed the first thread - anyone got a link?

old mart11/01/2022 21:39:59
3717 forum posts
233 photos

Would it be possible to highlight the figures stamped or engraved on the brass parts?

Does anything show through the large holes when that disc is turned?

Edited By old mart on 11/01/2022 21:41:45

Former Member11/01/2022 21:48:45
1085 forum posts

[This posting has been removed]

Grindstone Cowboy11/01/2022 22:04:45
854 forum posts
64 photos

This is the original post (I hope).


Nigel Graham 211/01/2022 22:13:19
2009 forum posts
27 photos


I don't have a link but I think it was around this time last year, and in The Tea Room.


Well, - two blanks drawn today.

Not a pipe-organ design tool. (Despite the complexities of the pitch series, and stops labelled in odd fractions of feet).

Not a textiles trade instrument, as Ady suggests. (They usually work in even numbers.)

With thanks to Harrison & Harrison, and Newtown Textile Mill, respectively - and they'd love to hear back if - when? - we identify it!


Neil -

I reckon you are right - try the Science Museum!


So, what other trades may use very specific arithmetic and curious-looking numbers? Bear in mind the device is dated "Copyright 1908", so English-language and so likely to be for people working in Imperial units, including that long back, the more far-out units like bushels and pecks. (Mechanical and electrical engineers of the time used the regular units familiar to us, and the ºF, Calorie and BthU.)

Examining it closely, it's fairly clear the outer ring, divided into 20, is meant to be revolved clockwise against the 20-space scale, but the inner disc goes anticlockwise, controlled by the wire detent that has worn a very faint groove between the 30 holes it engages. It's been well used, even to the extent of the two inner circles of graduations being polished shallow.... but used by whom for what?

Agriculture / horticulture? (E.g. seed / yield estimates - but it seems too complicated for that.)

Brewing? (Recipe calculations)

Coopering? (Wooden casks of a range of sizes no longer used, such as the Pin and Barrel.)

Shipwrighting? (Especially wooden hulls.)

I've even wondered if it was part of some purely mechanical form of enciphering system, perhaps to create the cipher key in some precursor to the 'Enigma', whose history goes back quite a bit further than WW2 and originally for commercial not military secrecy. That might explain the 20/30 stepping, but the fractions and 16X table make me doubt this.


Another thought...... Is it closer to home than we've realised?

The clock-makers on this forum would have said "Yes - that's ours!" if this was a horologist's circular slide-rule; but their published designs show "ordinary" trigonometry and basic gear-ratio sums, and no Sixteen-Times-Table.

What though of our brother hobby as was enjoyed by His Majesty King George the Third no less - Ornamental Turning. Any here? Is this thing a calculator for setting some of the more complicated harmonic chucks?

pgk pgk13/01/2022 11:03:48
2549 forum posts
293 photos

Why copyright? I’ve just had a bit of a dig about and copyright law at that period was mostly for printed works?
Apparently the UK was signed up to the Berne Convention which had a review in 1908 - coincidence?

It did make me wonder if this could be a calculator for print - mixed sizes of characters on a type-set page?


DMB13/01/2022 12:10:25
1293 forum posts
1 photos

Try asking The SMEE?

Nick Clarke 313/01/2022 12:26:09
1391 forum posts
61 photos
Posted by pgk pgk on 13/01/2022 11:03:48:

It did make me wonder if this could be a calculator for print - mixed sizes of characters on a type-set page?


I think it unlikely - fractions are not really part of print design and the numbers bottom right are really too big - type of 144pt would usually be inserted as a block, not type.

Also before the days of computers print shops would not have the large range of typefaces and font sizes we have easily available today so this would probably not be necessary for a skilled typesetter working with a restricted range of type.

Nick Clarke 313/01/2022 12:36:15
1391 forum posts
61 photos

The issue with a device such as this is that it could be for any trade or profession and within that for any particular material or piece of equipment.

What is stirring these thoughts is the Unitol calculator that was used to determine the developing times for one particular product, a developer, from one manufacturer. No other developer manufacturer would use the same rotary calculator, and Johnsons, who made Unitol would not use it for any other of their products.

If they had not 'Developing Times' on it it might be as much a mystery as this one!


Oldiron13/01/2022 15:15:30
960 forum posts
40 photos

I have trawled through my countless calculator books and have come up with nothing. Also spent many hours on the internet since the first post and nothing found. As a collector of Mechanical calculators and slide rules I will be very interested to know its origins & usage.


Peter Cook 613/01/2022 15:48:28
258 forum posts
73 photos

Just a random idea - It s a calculator/convertor for precious metals. One measurement system used is the pennyweight , which is one 240th of a Troy pound, one 20th of a troy ounce (hence the 20 holes in the outer ring and is subdivided into 24 grains (the holes in the inner ring?) possibly the 48ths are half grains.

The fractions round the edge are all the approximations to the 16th's with correction factors for 48ths or 240ths. So for example 9(/16) is 3/5 + 9(240ths) and 7/12 +1(48th).

The only place pennyweight is still used ( and was still used in 1908 - it lost it's official status in 1878) is in the precious metals trade.

What it does and how it works I don't know, but the involvement of 16th's suggest it might be for converting the archaic troy/pennyweight system to the avoirdupois (1 lb = 16 oz).

Just my two pennyweight's worth.

Juddy13/01/2022 16:23:29
101 forum posts

This is a guess but could it be for rope or cable making, calculating the number and size of wire strands to form a cable of a given strength or finished size

Calum Galleitch13/01/2022 22:59:54
166 forum posts
50 photos

Sector 1: 1/15 - 1/240 = 1/16, as does 1/12-1/48

So why the plus sign? Since some of the fractions given are improper, I think the point is to take an input from a process, which may arrive as an uncancelled fraction (say 6/8) and use that as an input to this device.

Since the plus and minus signs appear to be reversed, perhaps the purpose of this device is to generate some sort of correction.

Whatever it is, it seems to be a fundamentally mathematical process, based around sixteenths.

Lastly: there seems to be a sort of symmetrical correspondance, sectors 2 and 14, sectors 3 and 13, and sectors 12 and 4. But it doesn't continue, at least obviously. Why are sectors 7, 11, and 15-18 blank? Why is there no sector 19?

I don't think it is to do with Troy weights: one Troy pound is 12 Troy ounces, made of 20 pennyweights, consisting of 24 grains.

SillyOldDuffer14/01/2022 11:35:28
8469 forum posts
1885 photos
Posted by Calum Galleitch on 13/01/2022 22:59:54:

Sector 1: 1/15 - 1/240 = 1/16, as does 1/12-1/48

So why the plus sign? Since some of the fractions given are improper, I think the point is to take an input from a process, which may arrive as an uncancelled fraction (say 6/8) and use that as an input to this device.

Since the plus and minus signs appear to be reversed, perhaps the purpose of this device is to generate some sort of correction.


Spotting a pattern emerges when the sign is inverted must be important, but I'm still baffled. Pretty certain the device isn't doing a simple conversion of any of the usual weights and measures candidates like pounds to ounces. Generating corrections is an interesting idea: that or something else non-obvious. The ratchet suggests an additive process.

Another oddity is the thing is Copyright rather than Patented. Copyright protects expression of ideas such as art, novels etc rather than a device or algorithm. I guess the mechanism inside is nothing special, perhaps a couple of gear wheels, but the application itself was novel.


Edited By SillyOldDuffer on 14/01/2022 11:36:07

Nigel Graham 214/01/2022 11:48:52
2009 forum posts
27 photos

Blanks drawn with musical-instrument making and textiles manufacture, I turned to slide-rule making.

The Weymouth company, Blundell-Harling (est. 1948) stopped making conventional arithmetical slide-rules decades ago when the electronic calculator arrived, but still makes special-to-trade slide-rules, many of them circular, and a range of drawing-boards. Its sales manager was unable to identify it but directed to me to the vast array of all sorts of odd calculating instruments she'd found via Google. Among them was another photo of our Old Faithfull, on Reddit.

She too, concluded by asking me let her know when (if!) we identify it!


Next I examined the Science Museum's on-line exhibition.

The nearest was a late-19C device looking very much a brother product to our specimen, similar in design essentials to its discs, used in creating cyphers. The resemblance suggested at least the same manufacturer, but it was alphabetical not arithmetical. (I tried to copy the photo to here, with acknowlegement of course, but unsuccessfully - might be a protected image.)


Juddy -

Interesting idea. Our calculator is contemporary with considerable use of ropes for power-drives and transport systems, as well as load-lifting and standing-rigging.

Henry Spooner's Machine, Design and Construction (Longman, Green & Co, 1913) details vegetable-fibre, leather and steel-wire rope construction and use, but although very mathematical it shows no obvious links to the maths we have here.

Peter Cook suggests Precious-Metals weighing; Calllum thinks not; but together they made me ponder Apothecary:

The English version of the [Apothecary weights] system is closely related to the English troy system of weights, the pound and grain being exactly the same in both.[4] It divides a pound into 12 ounces, an ounce into 8 drachms, and a drachm into 3 scruples of 20 grains each. (Wikipedia)

Now, do those factors fit?

Fixed scale: 20 (0-19 though showing no printed "19 " seems odd).

Intermediate, rotary scale: 20. Central scale: 30 (0-29).

Many but perhaps not all of the fractions are ratios of factors or multiples of those numbers.


That Science Museum search, I am afraid, was very frustrating by its own web-site; of a standard I regard too low for a national Science Museum! It uses a filter system as in major retailers' catalogues, but it is very rough, its date-choice system largely meaningless, and can take only one criterion before switching back to the list.

Consequently, however I entered the request, it randomly mixed all the various calculators and slide-rules - including one for treadmill-labour arithmetic - with any number of objects irrelevant to the subject.

Worse though, this had a very unexpected, rather distressing result.

Most were early medical instruments.You'd expect some Victorian - Edwardian medicalia to look not very pleasant, and though the "Vibrator" amused me (no - not Ann Summers, " Therapy" ), one of these chance finds gave me a shock hard to shake off. It is a knife with hook-shaped blade, and labelled "Decapitating Knife". Its category? "Gynaecology & Obstectrics".


Edited By Nigel Graham 2 on 14/01/2022 11:50:41

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