eared to be greatly agitated.

"Come here," he cried, seizing each of them by the arm; "I've got
something to show you."

"Well, what is it?" asked the other two. Their friend, however, would
vouchsafe no further reply than, "Come here out of the way, and I'll
tell you."

He dragged them along until they reached the deserted entrance to some
of the classrooms; then, stopping and turning to them with an
extraordinary look of mingled triumph, mystery, and excitement,
exclaimed,--

"I've read the cipher!"

"Pooh! what of that?" answered Jack, rather annoyed at being taken so
far out of his way for nothing. "I expect it isn't anything particular
after all."

"It is, though," returned the other confidently; "and you'll say so too
when you read it."

"Well, tell us first how you managed to find it out."

"That's just what I was going to do. You know I found that G was T, S
was H, and V was E; well, I tried and tried, and I couldn't get any
further. I wrote down the alphabet, and put V opposite E, and T
opposite G, and S opposite H. I stared at it and stared at it, and all
of a sudden--I don't know how I came to think of it--I noticed that E is
the fifth letter from the _beginning_ of the alphabet, and V is the
fifth letter from the _end_. The same thing held good with the next
letter: G was seventh from the beginning, and T was seventh from the
end."

Diggory paused as though to see what effect this announcement would have
on the faces of his friends.

"Well!" they exclaimed; "go on!"

"Why, then, I saw in a moment what they'd done: _they'd simply
transposed the whole alphabet_--A. was Z, and Z was A!"

"Oh!" cried Jack Vance; "I see it now."

"Of course, it was as plain as print. I put the two alphabets side by
side, one the right way and the other upside down, and I read the cipher
in two minutes, and here's what you might call the translation."

As he spoke he held out a scrap of scribbling-paper. Jack Vance took
it, and read as follows:--

"Meet in the 'gym' when the fellows pass on to supper. The two cans of
water are standing inside the cupboard under the stairs."

Mugford stared at Jack Vance, and Jack stared at Diggory. "D'you see?"
cried the latter eagerly.

"Yes."

"Well, what then?"

"Why, it must have something to do with this row about Browse."

"Of course: the fellows who did it didn't want, I suppose, to be seen
talking together too much just before it happened, and so they i