I have a complete set of encyclopaedias on my bookshelf, beautifully bound and neatly arranged with volume 1 on the left and volume 32 on the right. They were a talking point when I bought them 30-odd years ago and were regularly used, but as the internet took off so my use of them declined, preferring to use the online resources which were so conveniently at my fingertips.
So it was that the books remained unexamined for a number of years, until I recently moved house, whereupon I discovered an awful fact: an insect larva - specifically, a bookworm (Anobium punctatum, I've been told) - had found its way into the books and had munched its way through them.
The entomologist who identified it for me was curious about it, and took it for study. One question she did ask, though, was just how far the creature had travelled. I looked back at the books and, as I'd previously noted, confirmed that it had started at the first page of volume 1 (evidence suggests that it hatched there, the parent having departed a different way) and had travelled until it had reached the final page of the final volume, which is where I discovered it, so I gave this information to her, along with the measurements of the books, which were all identical:
- each cover is 6 mm thick
- each book is 40 mm thick in total
So, how far had the bookworm gone?