Tuesday, August 10, 2010

Reconstructing the History of Science, in LEGOs

Posted by Darin Hayton on 08/10 at 10:46 PM

The U.S. Civil War has long been the purview of historical reenactments—battle after battle (schedules of upcoming reenactments are available from various sources as well as reenactment supplies, e.g., Civil War Reenactment HQ and the competing The American Civil War Historical Re-enactment Society). History of science’s version of reenacting seems to focus on reconstructing scientific instruments (one of the members of The Delaware Valley Amateur Astronomers group regularly brings out a range of historical telescopes from his Galilean and his Newtonian on up). In many cases, the reconstruction attempts to replicate the original in materials, construction, look, feel, and other artifacts (what some people would call “flaws” or “inaccuracies”).

Andrew Carol has taken reconstruction to a new level with his LEGO constructions. Carol, a software developer at Apple Computer Inc. (according to this site) seems to have built two historical devices: Charles Babbage’s Difference Engine and the Antikythera Mechanism. I confess that I don’t quite understand the motivation to reconstruct historical scientific instruments out of LEGOs, but here is how he describes his hobby:

Having always loved complex mechanical devices, and never having fully outgrown LEGO, I decided to explore where computational mechanics and LEGO meet. This is not LEGO as toy, art, or even the MindStorms® fusion of LEGO and digital electronics. This is almost where Steampunk and LEGO meet. Hand cranked devices that perform complex mechanical tasks.

Carol has built three versions of Babbage’s Difference Engine. The newer version has the added benefit of being able to calculate 3rd order differences to 4 digits of accuracy and uses only standard LEGO blocks:

Andrew Carol’s reconstruction of the Difference Engine (Source: Original, full-size image is at Andrew Carol’s site, here)

The latest version “is significantly easier to assemble and align. It also operates five times faster than the 2nd generation machine. This is done with an eye to making it easier for others to build their own Difference Engines.”

Carol’s Antikythera Mechanism is as impressive as his Difference Engine and as seemingly quirky. He doesn’t indicate whether or not he had to modify any LEGO blocks to build this model, though rest assured, if he did have to modify any blocks he will certainly design a new version that uses only standard LEGOs.

Andrew Carol’s Antikythera Mechanism (Source: Original, full-size image is at Andrew Carol’s site, here)

For a full appreciation of these two devices and Carol’s work, see the short movies showing both machines in operation on Carol’s website, which for what it’s worth is hosted at Steve Wozniak’s URL. Having watched the videos and thought about Carol’s efforts, it is unclear to me why somebody would bother to build devices. Perhaps as a personal challenge or a hobby. Maybe as a parody of all the people who reconstruct historical scientific instruments, though I doubt it. But beyond that I see little point. But then again, I see little point in reenacting Civil War battles.

Finally, for those interested in building their own complex machines using LEGO blocks, Carol offers this advice:

In complex LEGO gear trains where accuracy is important, it is critical that all multiplication be done before division. Multiplication increases the inherent gear-to-gear error, division reduces it. To achieve the greatest possible accuracy, the error should be reduced as small as possible just before the output.

1He is not alone in constructing LEGO models.  See, for example, the former architect turned modeler Adam Reed Tucker’s LEGO models of famous buildings architect turn.

Tags: antikythera mechanism, charles babbage, difference engine, lego