From Alex Saragosa, Terranuova Bracciolini, Italy
Matthew Stevens rightly points out that, in a few millennia’s time, it will be difficult to read nanometric information etched into glass, given that, by then, the necessary reading technologies will probably have been forgotten. But there is a very simple solution: engrave th information onto the glass, but then carve the instructions for building the necessary readers onto stone slabs, aiming for the simplest possible version of the reader and including plenty of explanatory illustrations. If hieroglyphics have survived to the present day, that information will also reach future generations (Letters, 21 March).
