"They do, but I don't know that it's much of an advantage. Had you any
other reason for modifying the construction plans?"
Dick felt embarrassed. He gave the Adjutant a quick glance; but the man's
face was inscrutable. Captain Hallam was a disciplinarian where
discipline was needed, but he knew the value of what he called
initiative.
"Well," Dick tried to explain, "if you notice how the wash of the
head-rapid sweeps down the middle of the pool----"
"I have noticed it," said the Adjutant dryly. "That's why the bridge
makes a slight sweep. But go on."
"We found a heavy drag on the center that flattened the curve. Of course,
if we could have pushed it up farther, we'd have got a stronger form."
"Why?"
"It's obvious, sir. If we disregard the moorings, a straight bridge would
tend to curve downstream and open out under a shearing strain. As we get
nearer the arch form it naturally gets stiffer, because the strain
becomes compressive. After making the bridge strong enough for traffic,
the problem is to resist the pressure of the current."
"True," the Adjutant agreed with a smile. "Well, we'll let the pontoons
stand. The traditions of the British Army are changing fast, but while we
don't demand the old mechanical obedience, it might be better not to
introduce too marked innovations. Anyhow, it's not desirable that they
should, so to speak, strike a commanding officer in the eye. Some
officers are conservative and don't like that kind of thing."
He moved on and Dick wondered whether he had said too much. He was apt to
forget his rank and comparative unimportance when technical matters were
discussed. In fact, it was sometimes difficult not to appear
presumptuous; but when one knew that one was right---In the meantime, the Adjutant met the Colonel, and they stopped together
at the bridge-head.
"I think we have made a good job, but the brigade's transport is pretty
heavy," the Colonel remarked.
"I'm satisfied with the bridge, sir; very creditable work for beginners.
If the other branches of the new armies are as good----"
"The men are in earnest. Things, of course, are changing, and I suppose
old-fashioned prejudices must go overboard. Personally, I liked the type
we had before the war, but we'll let that go. Young Brandon strikes me as
particularly keen."
"Keen as mustard," the Adjutant agreed. "In other ways, perhaps, he's
more of the kind you have been used to."