The solution of the problem came to him all of a sudden--as the solution
of arithmetical problems often does come. He saw the whole thing quite
plainly and wondered that he had not seen it at a first glance. The
figures represented nothing whatever but three plain and common sums--in
compound arithmetic. Cotherstone, for some reason of his own, had taken
the sum of two thousand pounds as a foundation, and had calculated (1st)
what thirty years' interest on that sum at three and a half per cent.
would come to; and (2nd) what thirty years' interest at five per cent.
would come to; and (3rd) what the compound interest on two thousand
pounds would come to--capital and compound interest--in the same period.
The last reckoning--the compound interest one--had been crossed over and
out with vigorous dashes of the pen, as if the calculator had been
appalled on discovering what an original sum of two thousand pounds,
left at compound interest for thirty years, would be transformed into in
that time.

All this was so much Greek to Stoner. But he knew there was something in
it--something behind those figures. They might refer to some Corporation
financial business--Cotherstone being Borough Treasurer. But--they might
not. And why were they mixed up with Wilchester?

For once in a way, Stoner took no walk abroad that night. Usually, even
when he stopped in of an evening, he had a brief stroll to the Grey
Mare and back last thing before going to bed. But on this occasion he
forgot all about the Grey Mare, and Popsie the barmaid did not come into
his mind for even a second. He sat at home, his feet on the fender, his
eyes fixed on the dying coals in the grate. He thought--thought so hard
that he forgot that his pipe had gone out. The fire had gone out, too,
when he finally rose and retired. And he went on thinking for a long
time after his head had sought his pillow.

"Well, it's Saturday tomorrow, anyway!" he mused at last. "Which is
lucky."

Next day--being Saturday and half-holiday--Stoner attired himself in his
best garments, and, in the middle of the afternoon, took train for
Darlington.

CHAPTER XV

ONE THING LEADS TO ANOTHER

Although Stoner hailed from Darlington, he had no folk of his own left
there--they were all dead and gone. Accordingly he put himself up at a
cheap hotel, and when he had taken what its proprietors called a meat
tea, he strolled out and made for that part of the town in which his
friend M