To observe a human sweep a room would be less than stimulating, but watching a robot do the same thing is marvelous.

A Wall Street Journal essay on the pleasures of watching the robotic vacuum cleaner Roomba execute its algorithm (using software originally developed for land mine clearance) includes this acknowledgment:

[T]hese robots work more slowly than you or I would. A human wielding a broom and dustpan can be shockingly efficient. I've clocked it: In my modestly sized rooms, the time it takes to prepare, deploy and clean the robots isn't much less than what it takes to vacuum or sweep.

The author, Michael Hsu, is pointing to a phenomenon that goes well beyond contemporary robotics: the fascination and pleasure people take in seeing machines perform. How else can we explain the success of tourbillon watches among the one percent. Yet the original purpose of the tourbillon was to compensate for the effect of keeping pocket watches in fixed vertical positions all day. As a senior timekeeping curator of Britain's National Maritime Museum, Jonathan Betts has put it:

Having a tourbillon in a wrist watch is difficult to justify technically as, unlike pocket watches, wrist watches are constantly assuming different positions anyway, and the tourbillon is unnecessary. Most wrist watches fitted with tourbillons are made principally as showpieces.

It's thrilling to see a tourbillon in action. Even many luxury watches without such refinements have glass backs revealing the functioning of the mechanism.

The cultural historian Neil Harris has coined a phrase for this fascination with seeing things work, the Operational Aesthetic. One of the pleasures of bowling for postwar generations was the introduction of the automated pinspotter, the Roomba of the 1950s, which helped the sport's explosive growth in the decade.

Who started it all? Harris has suggested it was none other than P.T. Barnum, whose American Museum in New York was widely (and rightly) suspected of fakery. But that helped build business. Visitors wanted to see for themselves, scrutinize the exhibits closely, and detect just how each illusion was accomplished. Barnum's success was based not on cynicism about "suckers," but to the contrary, in appealing to critical intelligence to detect how it all was done.

Many people, including some who could afford any watch, consider tourbillons and other luxury timepieces, no matter how beautifully made, to be humbugs when virtually everybody has a cell phone that never is off by a second. And even favorable reviews of the Roomba acknowledge that it really isn't a substitute for a more powerful conventional upright or canister machine. But as Michael Hsu concludes, efficiency

is beside the point. There's a joy from watching something undertake a task that's challenging for it but easy for you.

Barnum, whose American museum acts included a flea circus and a loom run by a dog, would surely have agreed.