HOWTO maintain a Difference Engine

Here's a set of instructions for operating and maintaining the replica of Charles Babbage's mechanical computer -- the storied difference engine -- built and displayed in 1991 at London's Science Museum to commemorate the bicentenary of the birth of Charles Babbage.

If the Engine is being demonstrated on a daily basis, lt should be oiled and greased at least once a week. If no demonstrations are taking place, then the Engine should be oiled and greased on a monthly basis, but the handle should be turned at least twice a week to cycle the mechanisms.
Grease : "Alvania" grease or it's equivalent should be used.
Grease
1. all vertical motion cam profiles only and their levers.
2. all bevel gears above and below the cam stack.
3. all bevel gears on the carry axes and those on the carry drive shaft.
4. the phasing gear, register pinion, "Impact tooth and the tw-in tooth drive.
5. the pawl wheel and crank pinion.

INSTRUCTION MANUAL to Operate and Maintain Charles Babbage's 2nd Difference Engine (via Hack the Planet)

(Image: The Difference Engine, a Creative Commons Attribution photo from Adactio's Flickr stream)

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samanth0r

I had no idea this existed. I MUST GO SEE IT! I <3 Babbage. (although he really did hate musicians…)
Anonymous

You have no idea how many of them are still in use. I used to make a living of greasing these little puckers. No that everyone now how to do it themselves I’ll be out of business soon!

Thank you boingboing.
shadowfirebird

::sigh:: It’s not a computer. You can’t program it.

All it does is turn out sheets of logarithm tables. If you want a different set of tables, you have to take it apart.

Yes, it was an incredible breakthough — not only a quantum leap forward, but it would have been insanely useful.

But it’s not a computer.
Cicada

Well, crud. Now that those details are public, it’ll only be weeks before we see the first difference engine viruses propagating.
bcsizemo

WD40?! *sigh*…

I wouldn’t see why this wouldn’t be stored in an airtight vacuum sealed glass box. Keeps the moisture and dirt out. Oiled once it should be good for a couple of years.
Beanolini

#5, bcsizemo:

I wouldn’t see why this wouldn’t be stored in an airtight vacuum sealed glass box.

The instructions do state that this example is housed in a glass case. Even a vacuum-sealed one would still need lubricating, though- there’s no mechanism to pump oil or grease to the moving parts, so it will eventually migrate out and need replacing (hence the instruction to empty the ‘drip trays’).

I am slightly disappointed that the phrase “Reassembly is a reversal of the above procedure” was not used.
Vee

It was a computer – or at least a proto-computer – in the sense that Babbage designed the thing as a mechanical replacement for the human computers of the day, thus eliminating the human error which infuriated him so much. Computers were simply people who carried out computations according to a set of instructions.

Incidentally, there was a great ‘In Our Time’ episode broadcast in March. The topic was Ada Lovelace but there was, inevitably, tonnes about Babbage and both of the Engines. I think you can still listen to it:

http://www.bbc.co.uk/radio4/history/inourtime/inourtime_20080306.shtml
shadowfirebird

@Vee

It was a computer – or at least a proto-computer – in the sense that Babbage designed the thing as a mechanical replacement for the human computers of the day [...]

I curious — if I described your car as a horse, on the basis that it was designed to replace one, would you consider that a good use of English? :)

Not a computer in the modern sense of the word, though, you agree?
Vee

I wouldn’t describe my car (which I don’t have) as a horse but I would describe it as a vehicle – a happily fitting term.

But fair point. Babbage’s device was a far cry from the laptop I’m typing this on. However, it’s an interesting missing link in terms of the evolution of the application of the term ‘computer’.

The link I posted in the above comment is for a radio programme broadcast on BBC radio 4. It’s interesting I think because they (Doran Swade included) acknowledge that the retrospective interest in The Difference Engine belies the relative lack of influence the unfinished machine had on actual (modern) computing innovation.

I suppose in a roundabout way I’m saying I’m not disagreeing with you but that Babbage absolutely considered Difference Engine #1 to be a ‘computer’, regardless of what we now consider that term to mean.

Interesting, none the less, no?
Beanolini

#8, shadowfirebird:

I curious — if I described your car as a horse, on the basis that it was designed to replace one, would you consider that a good use of English? :)

Well, it wasn’t really designed to replace the horse, more to replace the carriage. So you might want to describe it as a carriage. Or perhaps a ‘horseless carriage’, similar to ‘mechanical computer’.

You’d probably get tired of saying ‘horseless carriage’ all the time, though- you might want to shorten it a bit. Perhaps the first three letters would do. ‘Hor’ it is, then.
shadowfirebird

@Vee, Beanolini:

Definitely interesting. Definitely a missing link. But I do think that Babbage seems to get the credit for inventing the computer, and I’m not convinced. The Jacard Loom seems at least as honourable a precursor.

From now on I will be describing my car as a ‘hor’, welcoming the inevitable japes about negotiable affection whenever I approach a filling station.
Anonymous

IIRC, the Analytical Engine originally used a pegged drum (like a music box drum with its pins) as the micro program store, rather than Jaquard Loom style cards – though it was a work in constant flux of development, so he may well have modified it to use the cards at a later date. Enhancement or upgrade? We’ll never know…
Anonymous

The one at the Computer Museum in Mountain View has a printer, too.

Check their website to make sure they still have it, I think it was only going to be there for six months.
Tom Fury

I don’t know about the rest of you, but I know I get really cranky if somebody doesn’t turn my handle at least twice a week.
Anonymous

@Shadowfirebird

“But I do think that Babbage seems to get the credit for inventing the computer, and I’m not convinced.”

Are you perhaps unaware of his later, and even more extraordinary invention, the “Analytical Engine”? It was a fully programmable computer, using Jacquard loom-type punch cards for input.
Anonymous

Words are funny things. Arguably “computer” is like “ship” and “missile” in that have both a general meaning AND a specific meaning that is a subset of the general meaning, causing confusion. When we say that “the schoolboy was pelted with missiles,” or gamers talk about “missile weapons,” they’re rarely talking about guided missiles. And yet somebody who refered to unguided rockets as missiles would get a ticket from the pedant police. As would somebody who referred to an ocean-going schooner as a “ship.”
Nelson.C

ShadowFireBird @11: Way back in the day, when I was taking my Computer Studies ‘O’-level, both the Difference Engine and the Jacquard Loom featured prominently in the history part of the course.

Maybe these days Babbage’s machine gets more popular attention, but that may be down to the Gibson and Sterling novel, or because of the almost-existence of the Analytical Engine, which was more computer-like and which Babbage and Lovelace did a lot of theoretical work on. Whereas the Jacquard loom, as far as I know, didn’t directly lead to a more computer-like device.
PaulR

Alvania grease:
“Low noise grease for use in nosie critical small electrical motor applications”
http://www.shell.com/static/tw-cn/downloads/shell_for_businesses/industry/product_data_sheet/english_version/alvania_rlq2.pdf

Man! All this time I though it was spelled ‘Nosy’.

It just goes to show ya…
(BTW, it’s non-conductive lithium grease.)
(WD-40 – for Water-Displacement, 40th formula – might be OK for preventing corrosion from water, it’s a poor lubricant. Especially when the part calls for grease.)
Anonymous

It absolutely is a computer, currently programmed to produce logarithmic tables. You can reprogram it by disassembling the linkages and rearranging the components. Ease of programmability is not a required character of computers.

The great advantage of the programmable digital electronic computer (as opposed to, say, the programmable analog electrical computer, or a non-programmable fixed-purpose computer) is that the programming can be contained in electrical patterns that are very easily stored, recalled, and loaded – no cards (such as used in Jacquard looms) required.

The first known computer is the Antikythera mechanism, Jacquard and Babbage aren’t even in the right century. http://en.wikipedia.org/wiki/Antikythera_mechanism

A car will still be a car if it has a fixed speed engine. A computer is still a computer even if it is very difficult to program.

Try programming a SEL machine from an 8-bit switch panel, calculating the rotational speed of the giant magnetic drum as part of your programming effort. Try building an image overlay file for a taskbuilder that will let you run a 2MB executable image on a machine with 1MB of addressable memory (obsolete technique since the invention of the DEC VAX). Those tasks are not much easier than dissasembling a difference engine and cutting new cogs, I bet.
teufelsdroch

MIT’s differential analyser deserves some love, too.

http://www.computermuseum.li/Testpage/Differential-Analyzer-1931.htm

Goes back to Kelvin; MIT originally built a demo version from Mecanno (erector set) parts.
mdh

Turn handle weekly, Tickle fancy daily.
nanuq

Would it void the warranty to use WD40 instead?