My dear boy, I am delighted and thankful to see you again. I tried to
persuade our friend Mr. Hobart, when I last saw him at Santa Fe, that,
in spite of your performance on that railroad ride you and I took
together last summer, you were too young to make the trip I had laid out
for him. He said he didn't know anything about your age, but that you
were certainly strong and plucky enough for the trip. I made him
promise, though, to try and induce you to go back from Isletta; but he
doesn't seem to have succeeded."

"No, sir," laughed Glen, "and I'm awfully glad he didn't, for it's been
the most glorious kind of a trip, and I have enjoyed every minute of
it."

"I am glad, too, now that it is all over; but I must tell you that, if I
had not been assured that you were a whole year older than my young
secretary here, I should have insisted on your going back, for I
considered it too hard and dangerous a trip for a boy so young as I had
supposed you to be until then."

Here was another good reason why Glen was glad he had remained silent on
the subject of his birthday.

"Now what do you think of running a line across the desert ahead of us?"
continued the chief-engineer; "are you as anxious to undertake that as
you were to cross Arizona?"

"Yes, indeed, I am, sir," replied Glen, earnestly. "I am anxious to go
wherever the second division goes; and if anybody can get a line across
that desert, I know we can."

"I believe you can," said the chief, smiling at the boy's enthusiasm,
"and I am going along to see how you do it."

The Colorado was so broad, deep, and swift that Glen wondered how they
were going to measure across it, and had a vague idea that it could be
done by stretching a long rope from bank to bank. He asked "Billy"
Brackett; and when the leveller answered, "By triangulation, of course,"
Glen showed, by his puzzled expression, that he was as much in the dark
as ever.

"You have studied geometry and trigonometry, haven't you?" asked the
leveller.

Glen was obliged to confess that, as he had not been able to see the use
of those studies, he had not paid much attention to them.

"Well, then, perhaps you'll have a better opinion of old Euclid when you
see the practical use we'll put him to to-morrow," laughed "Billy"
Brackett.

Glen did see, the next day, and wondered at the simplicity of the
operation. The front flag was sent across the river in a boat, and on
the opposite side he drove a stake. While