The libraries of the ancient world survived only by continual copying, and the slow crumbling of paper threatens ours as well. So Daedalus wants to be able to copy a closed book at speed. Ideally, the librarian should be able simply to load a block of books onto the copier, which would then transfer their contents to compact disk.

A paper page is about 0.1 mm thick, a typical infrared wavelength. It is composed of fibres of much finer diameter, so it should be pretty transparent to light with a wavelength of 0.1 mm or less. At such a wavelength, each page should be optically distinguishable from the pages on either side. A pulsed infrared laser beam launched perpendicularly into the side, top or bottom of the book, or into all three simultaneously, should illuminate one page only, and would follow it even if the page was a little bent.

A sufficiently narrow laser beam can trace a single line of type, or pick out single letters from successive lines. Each letter is an opaque indentation of the paper; it will absorb the light pulse a little, and this sharp attenuation will return a reflection, or 'echo', characteristic of the shape of the letter. A beam-splitter could then separate the stream of returning echoes into a photocell for computer analysis.

Unfortunately, a page is printed on both sides. At any printed site, the paper may be indented by two opaque letters, both of which will contribute to the echo. But this is where beams from all three sides come in. Each could be swung through an angle to illuminate any of several files of letters. Cunning software with linguistic knowledge will be needed to resolve the multiple ambiguities. But a closed page lit by pulsed lasers should be readable.

DREADCO physicists and librarians are now at work. Their prototype steps through a block of books at high speed, a page at a time. The final device will probably send its output to a compact disk, archival microfilm or miniprint on alkaline paper. Photographs and diagrams are a problem, but they could be identified by the software, and the book opened and photographed the hard way.

The new DREADCO book-copier will transform the task faced by the world's librarians. Instead of having to open every book at every page, they will merely have to load books in bulk into the copier. Its output will be far smaller, neater and more easily stored. The mighty achievements of the nineteenth and twentieth centuries will be faithfully recorded for future historians.