e interested spectators of the two concluding games which
were bitterly contested, went to deuce a number of times, but finally
were won by Della and Frank.

"Well, Jack," said Mr. Hampton, jokingly, as the players joined the
spectators at the conclusion of the set; "I suppose you were just
being chivalrous and that's why Della beat you."

Jack grinned. He and Bob knew they would be in for a certain amount of
twigging because of their defeat, but he knew how to take it in good
part.

"Chivalrous? Oh, yes," he scorned. "We'd have beaten that pair of kids
if we had been able. But it couldn't be done. Della's got a serve
there that would put Mlle. Lenglen to shame. As for Frank, the boy
goes crazy when he plays tennis."

A general laugh greeted his generous praise of his opponents. Then Mr.
Hampton turned to his companion and introduced him to the players as
"Colonel Graham."

After that the players hurried away to brush up and prepare for
dinner.

"Shall we speak of our discoveries this afternoon?" asked Frank,
brushing his hair while big Bob peered over his shoulder into the
mirror, adjusting his tie.

"Why not?" asked Bob.

"Well, on account of this Colonel Graham. Who is he, by the way,
Jack?"

Jack did not know. He recalled, or believed he recalled, that his
father had spoken of a friend named Colonel Graham who was a famous
engineer.

"But if he's a friend of Dad's," added Jack, with calm confidence,
"you can count on it that he's a good sport. It will be safe to speak
about our discoveries before him."

At dinner it developed that Colonel Graham was, indeed, a friend of
Mr. Hampton. They had been classmates years before at Massachusetts
Institute of Technology. During the World War, Colonel Graham had
obtained a reserve commission in the Engineers and, at the conclusion
of hostilities, while thousands of other officers were being
demobilized, he had been given a commission in the regular army
because of his distinguished record.

At dinner, the older people took the lead in the conversation, while
the boys and Della were content to listen unless addressed. Colonel
Graham was a brilliant conversationalist, and once he became launched
on a series of war stories there was no time for the boys to
interrupt, nor had they any inclination. He had been one of the
handful of American engineers impressed into a make-shift army by
General Byng to stop the Germans when they smashed through at Cambrai,
and his