ph! I never thought of that in my life."

"Most of us don't."

"I suppose that was why people began making clocks."

"You don't for a moment imagine men leaped from sundials to clocks, do
you?" interrogated the Scotchman quizzically.

"Oh, perhaps not such nice ones as ours," conceded the boy with easy
unconcern. "Still they had to tell time somehow."

"Clocks were a long way off from suns and shadows."

"But what did come next?"

"To sundials, you mean? Well, for a long, long time people could think
of nothing better. They introduced trifling remedies now and then,
however. For example, in the seventeenth century they evolved a portable
dial that could be carried from place to place. Sometimes this was
combined with a compass; sometimes it was made in the form of a ring. It
was an awkward substitute for the watch, but it was, nevertheless,
great-great-great-grandfather to it. Yet advantageous as it was to be
able to carry the time about with you, it did nothing to lessen the
long, unmarked stretch of darkness that descended upon the earth every
night. How was man to solve that difficulty?"

"How indeed?"

"That was his puzzle--his nut to crack. Throughout the ages it has been
conundrums like these that have taxed human ingenuity and made of life
such an alluring adventure. On the conquering of difficulties
civilization has been built up. Well, man now attacked this problem of
telling time. He did not aspire to narrow it down to any very fine
point, for at that period of history one day was very like another, and
he was a leisurely being with little to do but eat, sleep, fight or
hunt. Notwithstanding this, however, he did want to know _when_ it was
noon; _when_ it would be day. King Alfred, one of the English monarchs,
hit upon a plan for telling the hours of the night by means of tall
candles, made to burn a definite interval. When, for example, one of his
candles burned out, he knew that four or six hours had passed. Other
persons went further and had candles marked off into hours with black
and white wax--"

"That was a clever scheme!"

"Clever, yes; and all very well for kings who could afford to burn wax
tapers night after night. But there were, alas, many unfortunates who
couldn't. Accordingly the obstacle persisted, and urged the world on to
the next step up the time-telling ladder."

"And what was that?" demanded Christopher with interest.

"Telling time by water."

"By _water_! But how?"

"