would have saved young
Escombe some hours of arduous labour, and thus expedited the survey.

Now, it happened that a certain day's work terminated at the edge of a
_quebrada_, and Butler informed Harry that the first task of the latter,
upon the following morning, would be to take a complete set of accurate
measurements of this _quebrada_, before pushing on with the survey of
the route. A _quebrada_, it may be explained, is a sort of rent or
chasm in the mountain, usually with vertical, or at least precipitous
sides, and very frequently of terrific depth, the impression suggested
by its appearance being that at some period of the earth's history the
solid rock of the mountain had been riven asunder by some titanic force.
Sometimes a _quebrada_ is several hundreds of feet in width, and of a
depth so appalling as to unnerve the most hardy mountaineer. The
_quebrada_ in question, however, was of comparatively insignificant
dimensions, being only about forty feet wide at the point where the
survey line crossed it, and some four hundred feet deep.

Now, although Harry was only an articled pupil, he knew quite enough
about railway engineering to be perfectly well aware that the elaborate
measurements which Butler had instructed him to take were absolutely
unnecessary, the accurate determination of the width at the top--where a
bridge would eventually have to be thrown across--being all that was
really required. Yet he made no demur, for he had already seen that it
would be possible to take as many measurements as might be required,
with absolute accuracy and ease, by the execution of about a quarter of
an hour's preliminary surveying. But when, on the following morning, he
commenced this bit of preliminary work, Butler rushed out of his tent
and interrupted him.

"What are you doing?" he harshly demanded. "Have you forgotten that I
ordered you to measure very carefully the _quebrada_ this morning,
before doing anything else?"

"No, sir," answered Harry, "I have not forgotten. I am doing it now,
or, rather, doing the necessary preliminary work."

"Doing the necessary preliminary work?" echoed Butler. "What do you
mean? I don't understand you."

"Then permit me to explain," said Harry suavely. "I have ascertained
that, by placing the theodolite over that peg yonder,"--pointing to a
newly driven peg some four hundred feet away to the left--"I shall be
able to get an uninterrupted view of the _quebrada_ from top t