"Yes," replied Godfrey without surprise. "It wasn't measles, but if it
had been you might have caught them, so of course he was right to be
careful."

"Oh! he wasn't thinking of me or Mummy, he was thinking of himself,"
blurted out Isobel with the candour of youth.

"Big, strong men don't catch measles," said Godfrey in mild
astonishment.

"He says they do, and that they are very dangerous when you are grown
up. Why are you alone here, and what are you working at?"

"My father has kept me in as a punishment because I did my sums wrong.
The other boys have gone out bird-nesting, but I have to stop here
until I get them right. I don't know when that will be," he added with
a sigh, "as I hate rule of three and can't do it."

"Rule of three," said Isobel, "I'm quite good at it. You see I like
figures. My father says it is the family business instinct. Here, let
me try. Move to the other side of that big chair, there's plenty of
room for two, and show it to me."

He obeyed with alacrity and soon the brown head and the fair one were
bent together over the scrawled sheet. Isobel, who had really a
budding talent for mathematics, worked out the sum, or rather the
sums, without difficulty and then, with guile acquired under the
governess regime, made him copy them and destroyed all traces of her
own handiwork.