Charles Babbage's masterpiece difference engine comes to Silicon Valley

A full-scale model of the Charles Babbage-designed difference engine, on display at the Computer History Museum, in Mountain View, Calif. The difference engine will be exhibited for six months starting May 10. It was delivered Wednesday after traveling from London, where it was built at the Science Museum, the home of the world's only other full-scale difference engine. A difference engine is a calculation machine designed in the 19th century, which mechanically calculates polynomial functions.

(Credit: Daniel Terdiman/CNET News.com)

Update: This story has been corrected to reflect that the date of the public opening of the exhibit is May 10.

MOUNTAIN VIEW, Calif.--"Excuse me, Richard, we have a very large parcel."

With those words, spoken by John Shulver of London's Science Museum, a day of supreme geekery unfolded at the Computer History Museum here.

To be precise, the package in question was the delivery and installation of a difference engine, a brand new model of a 19th-century-era machine designed--but never actually built--by Charles Babbage. It was designed to be a mechanical calculator which can determine polynomial functions.

However, since Babbage invented the machine and never built it, and the only ones actually constructed were in the 19th century, the first one built in modern times was created in 1991 at London's Science Museum. Much more recently, tech millionaire Nathan Myhrvold visited the London museum and decided he wanted one for himself. So he commissioned the museum to build it for him.

Three and a half years later the machine was finished. But before it goes in Myhrvold's living room, it is going to spend six months on proud display at the Computer History Museum here. And on Wednesday, it was expected to arrive at the Mountain View museum.

The difference engine installed Wednesday at the Computer History Museum was built by lead engineer Richard Horton and includes a printer. The machine, of course, is entirely mechanical and has no electric functionality.

(Credit: Daniel Terdiman/CNET News.com)

However, partly due to the Olympic torch's passage through San Francisco, the grand machine's delivery was delayed for a couple of hours. And so as I--and many others--waited excitedly for its arrival, I was able to have an interesting conversation with Richard Horton, the metals and engineering conservator at the London Science Museum, and the lead engineer on the creation of the brand new difference engine.

Horton was on hand, as was Shulver--who assisted Horton with the last few months of the construction, for the arrival and installation of the machine.

He told me that he had been selected to build the new difference engine because he had been the one to craft a special Babbage-designed printer that was part of the Science Museum's machine. This, of course, after Myhrvold ponied up the million dollars needed to make another one.

Horton said that Myhrvold--who is expected to be on hand at a May 1 invite-only dedication ceremony at the Computer History Museum--is a collector interested in, among other things, historical computers. And as someone with the resources to pay for a difference engine--and the interest--he did so.

The process of making the new difference engine did not turn out as planned, Horton said. Along the way, there were a series of gaffes that led to a much longer construction time than expected.

The difference engine arrived Wednesday at the Computer History Museum. Here it is being lifted off its delivery truck while still in its red shipping cover.

(Credit: Daniel Terdiman/CNET News.com)

The most egregious mistake was that one of the companies contracted to create specific elements of the machine put parts of it under the wrong heat treatment, and in the process warped and cracked the cams--there are 14 sets of cams which control the engine's drums.

The problem with that, Horton explained, is that the malformed cams affected the difference engine's handle, which must be cranked to operate the machine. It was almost impossible to turn, he explained.

"It wouldn't have worked," he said. "No way."

The error cost the team six months of building time.

Another problem was that one of the main contracting firms working on the project went into liquidation just before the main construction process began, and that meant Horton and his small team ended up having to make many components and rework badly formed pieces themselves.

The biggest problem the contractor's liquidation presented the team with was that many of the machine's pieces had to be hand-fitted, and hand-filed so that they were in acceptable condition, Horton explained. That meant another four months' delay.

"For Victorian requirements," Horton said, speaking of Babbage's design constraints, "we had to be sure all the finishing (was as perfect) as we could meaningfully get them."

A shipping tag on the cover of the difference engine shows that it came from London's Heathrow airport and was intended to be delivered to the Computer History Museum in Mountain View, Calif.

(Credit: Daniel Terdiman/CNET News.com)

Ultimately, the machine's 248 figure wheels--gears used for computation--did fit properly onto their bearings, Horton said.

"Every one had to be done by hand," he said. "If there was tightness on any of the 248, the friction would have been massive."

It was a frustrating experience, he added, but "then we got the type of fit we wanted...It was better to fit them ourselves than have them be too loose."

Some might find it odd that people today are building machines based on a 19th century design whose creator never managed to bring it to fruition. But Horton said that for Babbage, the problem was financial: He simply didn't have the money to pull it off.

That's why it's so exciting to many that this new machine has come to Mountain View and will stay in the U.S.

Asked what we can learn from the machine, Horton said that it shows how engineering would have been done in Victorian times.

Amazingly, while today's computers can perform billions of calculations in a second, the difference engine could only do one--generally calculating algorithmic, trigonometric and navigational tables--every six seconds. On the other hand, the difference engine trumps today's machines for pure beauty.

So it should have come as no surprise that there was a crowd gathered just for the delivery of the machine. And even though the machine was hours late, the crowd lingered, snapping endless pictures when it finally did arrive--only to have a work crew spend an additional three hours or so simply getting the machine off the delivery truck. It took an additional couple of hours to get the machine into the museum.

Workers push hard as they attempt to get the difference engine up a slight incline on the walkway leading to the entrance of the Computer History Museum.

(Credit: Daniel Terdiman/CNET News.com)

But get it in they did, with the help of some clever on-the-ground engineering to get the 9,000-pound machine up a slightly inclined walkway and through and around a rather narrow entry way. (See more photos of the supersize unboxing in our photo gallery here.)

And when, at last, it had been shimmied into place, directly under a pair of specially installed chandeliers, the gathered crowd broke out in applause.

And that was even before anyone got to see the machine itself. All the while, from when it came off the truck, to when it was brought inside, it was under wraps.

But finally, Horton and Shulver began to rip the tape and covering off, and slowly but surely, one of the most beautiful pieces of machinery I've ever seen came into view.

When it did, I beheld a stunning piece of workmanship: 9 feet tall, with 8,000 parts, gleaming in the light and obviously never having been used before. The gears were spotless, the symmetry of all the parts was breathtaking and the obvious thousands and thousands of hours of work that went into it was just one of the best things I've ever seen in person.

It was so new, in fact, that one of the first things Horton did when he finished unpacking it was to wipe oil off many of the gears. And Shulver told me that over the next few days he and others would polish much of the steel so that it would shine like silver.

For Horton, meanwhile, the project is now pretty much over. He expects to be on hand for the May 10 opening, but then he'll have to go back to London and resume working for the museum. And it's unlikely he'll get to build another difference engine.

"I don't think any project...can compare," he said, wistfully. "It is (a once in a lifetime project)."

[Randys2cents]

Work of Art

This is an amazing work of art. Nice to see real craftsmanship is
still alive.

[WriteRight]

Babbage's Dream

It wasn't so much that Babbage ran out of money - the British government was footing the bill - but the fact that the design of his machine was simply beyond the ability of Victorian technology. Babbage had at the then astronomical cost of 50 000 pounds managed to build just half of the machine only to find that a slight stiffness of each of the multitude of cams added up to enormous friction that rendered the machine useless. Present day mechanical engineering remedies such problems using off the shelf standard ball bearings. In Babbage's times that just wasn't an option seeing that nearly every mechanical part, such as ball bearings, had to be hand crafted from scratch. It was after realising this did the government pull the breaks and write of its losses. Also it must have been a very stressful time for Babbage who suffered a number of what we would now call mental breakdowns.

[mopalia]

Babbage's dream

Actually, the Difference Engine #2, version 1, was built in 1991 at the Science Museum in London as proof of concept, and it was entirely constructed by hand, using precisely the tools and techniques available to Babbage. Many if the parts demanded precision not common at the time, and Clement, Babbage's machinist (reckoned to be the finest in England), developed tools to execute the design. One of Clement's workers, a fellow named Whitworth, came up with the world's first standardized screw thread. This machine at Mountain View was built the same way, and Richard, as mentioned in the article, was the engineer who built it. The only concession to the heavy load was a 4 to 1 gearing of the wheel which means that there are now four easier turns per cycle rather than the one turn Babbage designed.
Babbage's "breakdowns" may be more related to the tragic deaths of his wife and children, although the conflict with the government certainly didn't help. Doron Swade's "The Clockwork Brain" is about to be reprinted; reading that should clear up a lot of the popular mis-information that is about.