This is a man who wrote a 400 page history of the toothpick and even managed to get that book reviewed in the New York Times, even if the

reviewer did tell him to knock it off. I never read the toothpick book I have to admit, but I did read other books by Dr. Petrosky and I loved them.

His history of the pencil is amazing. Now, we economists have a strange relationship with pencils because a classic essay in economics titled

I Pencil is kind of an autobiography of a pencil which explains the decentralized genius of the free market economy. But Petrosky went way deeper into pencils, where they came from, how we overlook them, even how they get the lead into the middle of the pencil.

He meditated on their erasability, so indispensable to designers and engineers. Inc is the cosmetic that ideas will wear when they go out in public, he wrote. Graphite is their dirty truth.

Exhibit A in overlooking the pencil is Henry David Thoreau, the great 19th century American essayist. He once made a comprehensive list of supplies for an excursion, specifying obvious items such as a tent and matches, adding string, old newspapers, a tape measure and a magnifying glass, also including paper and stamps to make notes and write letters.

But as Petrosky points out, isn't this strange that he omitted to mention the very pencil with which he was making the list?

Well, maybe not, you think, until you realize that Thoreau and his father made their money by manufacturing high quality pencils. Thoreau was big pencil.

As for that perennial question about the pencil lead, and by the way it's not lead and it's never been lead, pencil leads are made from graphite.

When they first discovered graphite in the English lake district, underneath the roots of an old tree that was uprooted in a storm, well, they didn't know what it was, and they called it black lead.

But I digress, how do they get the graphite inside the wood? The trick is to take a slim slab of kiln dried wood and saw a row of grooves into the top surface.

Originally the grooves were square, easier to cut by hand. Now they're precision machined with a semi-circular cross section.

Once the cylindrical rods are laid into the grooves, you glue another grooved slab on top, this time with the grooves in the bottom.

Then all you have to do is cut the whole graphite sandwich into sticks, parallel to the graphite rods.

Those sticks are unformed pencils, plain, varnish, and the chop's done. And that is what you learn if you read Henry Petrosky.

But Petrosky was not only a toothpick and pencil guy, not at all. He was an engineer and a particular kind of engineer. He was fascinated by failure.

You can understand why I'm such a fan of the man. He once told the New York Times successful engineering is all about understanding how things break or fail.

One of his books, Success Through Failure, explored the way that engineers often advanced the field by building more and more ambitious buildings,

till eventually they exceeded what was possible and something broke, a bridge, a wall, a concrete multi-story car park.

The engineers learned, adapted, and moved on. That was one of the inspirations for my own book, Adapt.

And Petrosky was really, really thoughtful on the subject of engineering failure.

In 1981, two Skywalks at the Kansas City Hyatt Regency Hotel collapsed, killing 114 people.

...