THE INDUSTRIOUS BOOKWORM.
(
Unclassified Problems.)
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?
Answer:
The hasty reader will assume that the bookworm, in boring from the first
to the last page of a book in three volumes, standing in their proper
order on the shelves, has to go through all three volumes and four
covers. This, in our case, would mean a distance of 91/2 in., which is
a long way from the correct answer. You will find, on examining any
three consecutive volumes on your shelves, that the first page of Vol.
I. and the last page of Vol. III. are actually the pages that are
nearest to Vol. II., so that the worm would only have to penetrate four
covers (together, 1/2 in.) and the leaves in the second volume (3 in.),
or a distance of 31/2 inches, in order to tunnel from the first page to
the last.
