Today, more on images and reality. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

This week's issue of Mechanical Engineering features an article entitled "Relief for Weary Bones." It seems the Smithsonian's Triceratops skeleton has been on display since 1905. It may've been the first Triceratops ever put on display. Those old bones were protected by their sixty-five-million-year burial in the earth. But a century of mounted public display has taken its toll. The bones need to be treated and put away in padded cases.

Enter now a company called Virtual Surfaces, Inc. They do stereolithography, and they've been making three-dimensional digital scans of the bones. Now they're casting them in urethane. If a left rib is missing, they mirror-image the right rib and use it. They pull the iron supports and give the model a stance that's more reasonable in the light of current paleontology. They gradually fill in blanks and produce a complete and accurate skeleton that most of us would mistake for the real thing.

So what do we have when they're done? Are we being fooled or enlightened? While you think about that, here's a similar story from five and a half centuries ago. Gutenberg saw a chance to make a pile of money by making imitation manuscript books. He took the old art of printing to new heights, and began producing Bibles that were almost indistinguishable from real hand-written books. But his Bibles didn't have the inevitable errors that scribes made -- or the erasures or the nonuniformity of handwriting.

In neither case has anyone been deceived, but in both cases reality becomes blurred in disturbing ways. And the Smithsonian's Triceratops is only one example of something that's now very widespread. Our capacity for replicating, and even distorting, any reality is outrunning our ability to tell what's real.

You can now buy a CD of Rachmaninoff playing his own music. The recording was made from the best player-piano rolls. But then, like that Triceratops skeleton, the imperfections have been filled in and the music made complete. It's no longer the old piano roll. Neither is it really Rachmaninoff. At the same time it is, quite possibly, the best window into Rachmaninoff's genius that we have.

Go to the movies these days and tell me, if you can, where reality leaves off and imagination kicks in. Which of us didn't gasp as footage of the sunken Titanic took on color, life, and beauty.

The nagging subcutaneous question is, "Where's all this going?" It took a full generation after Gutenberg for society to feel the effects of the new presses. By the time they did, the shape of human knowledge, and how we used it, was being turned inside out.

Now we're increasing the flow and availability of knowledge orders of magnitude beyond Gutenberg. But we're also making a new reality of images. Most perplexing of all, we're gradually removing the need for much of the corporeal world that lies somewhere in the background of all that stunning unreality.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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Hutchinson, H., Relief for Weary Bones. Mechanical Engineering, Vol. 121, No. 6, June, 1999, pp. 54-57.

Rachmaninoff, S., A Window in Time. (realized by Wayne Stahnke) Telarc CD 80489