[Illustration]
Our friend Professor Rackbrane is seen in the illustration to be
propounding another of his little posers. He is explaining that since he
last had occasion to take down those three volumes of a learned book
from their place on his shelves a bookworm has actually bored a hole
straight through from the first page to the last. He says that the
leaves are together three inches thick in each volume, and that every
cover is exactly one-eighth of an inch thick, and he asks how long a
tunnel had the industrious worm to bore in preparing his new tube
railway. Can you tell him?