A NEW THEORY
“Those robbers probably came in a light, rubber-tired rig, left it
somewhere around the corner, got into the bank, did the job and drove
away again,” was the opinion of Mr. Thompson, as he crawled out of the
roof scuttle, followed by the boys.
“But how did they get to the roof?” asked Ned. “You’ve got to explain
that.”
“Easy enough,” spoke the policeman. “You see this bank is in a row,
with several other buildings, all about the same height. They could
have climbed up the fire escapes, or they could have used a ladder.
I’m inclined to the latter theory myself, for the fire escapes are on
the front of the buildings, and if they went up them they’d be seen,
whereas they could put a ladder up in back.”
The boys looked about them, and Bob took a couple of snap shots,
including one of his two chums and the officer as they stood near the
opened scuttle. As Mr. Thompson had said there was not much to see.
The roof was a long one, extending over several buildings, and being
flat, and covered with a composition of tar and gravel, alternating
with tin on some of the structures, made quite a place to stroll about.
Jerry walked a little away from Ned and Bob, who were listening to
Mr. Thompson’s explanation of how Detective Blake had discovered the
finger marks in the dust around the scuttle rim, and had thus made his
discovery.
“Blake thinks the scuttle was left unhooked, or else that the thieves
reached in with a bent wire, and lifted the hook from the catch,” said
the policeman.
The tall lad was walking over a stretch of tin roof, on a building
two or three doors from the looted bank. There had been rain two days
previous, followed by a brisk wind, which dried out the dust, and
there was now quite a coating of the latter on the tin. There was also
something else, and as Jerry caught sight of several marks in the
dirt-coating he uttered an exclamation.
“Somebody with rubber-soled tennis shoes has been walking up here,” he
said.
He bent closer over the footprints, and then he saw another mark that
caused him to spring up quickly, and call to his companions and the
policeman.
“Look here!” he cried, beckoning to them.
“What’s the matter?” demanded Ned, coming up on the run.
“Easy! Easy!” cautioned Jerry. “Don’t trample on these marks. Look! If
some one hasn’t been up here on a bicycle I miss my guess!”
“A bicycle!” exclaimed Bob. “Do you mean to say that the robbers rode a
bicycle up here?”
“There are the marks of the rubber tires plain enough,” replied Jerry,
pointing to them.
“That’s no bicycle track!” declared Ned.
“Why not?” the tall lad wanted to know.
“Or, if it is, the fellow rode on one wheel, or else is more expert
than anyone I ever saw. See, there’s only one straight mark, and the
best rider in the world turns his front wheel every now and then,
making a separate track from the rear one. That’s no bicycle mark.”
“What is it then?” demanded Jerry. “Did some one roll a single bicycle
wheel about on the roof for fun?”
Before Ned could reply, Bob, who had gone off several paces to the
left, uttered a cry.
“Here’s another!” he shouted, pointing to the dusty tin roof. His
companions hastened over, taking care to keep off the tracks, and
there saw another mark, exactly like the first.
For a moment Jerry Hopkins stared at the second impression. Then he
went back to look at the first one. Next he hurried forward and began
looking at a space about midway between the two tire tracks. His
companions and the policeman watched him curiously. Suddenly Jerry
threw up his hand as a signal.
“I’ve found it!” he cried.
“What?” asked Ned.
“The third track!” was the response. “Fellows it was no bicycle up
here. It was----”
“An aeroplane!” fairly burst out Ned and Bob together, for now, with
the discovery of the third impression, midway between and ahead of
the first two, it was very plain to anyone who had had to do with
aeroplanes that they were the marks of the three landing, or starting
wheels, of such a craft, that had left the marks in the dust of the
roof.
“An airship!” exclaimed the policeman. “Do you boys mean to say that an
airship has been up here?”
“It certainly has,” declared Jerry firmly. “Look here! There are more
marks farther on.” He pointed just beyond a blank space, where the
tin roof was clean of dust, and the marks were again visible in the
soft tar of another roof. “They landed here and made a start from here.
They could easily do it. In fact this long, flat roof with the tar
and gravel to give good traction, is an ideal starting place for an
aeroplane.”
“An aeroplane on the roof!” murmured the officer, as if unable to
believe it. “Do you think, Jerry----”
“I think,” interrupted the tall lad, “that the bank burglars came
through the air, made a landing here unseen by anyone in the street,
went down the scuttle, looted the safe, and made a flying start from
this roof.”
“Wait! Wait!” begged Mr. Thompson. “This is a new theory--I never heard
the like before. It needs a regular detective to consider this. Wait
until I get Blake up here. I’ll wager it’ll be news to him. Wait here
for me.”
He hurried down the scuttle, and the boys eagerly looked for more
impressions and talked about Jerry’s discovery. They went to the end of
the row of buildings, and there, where the roof was of tar and gravel,
they found in the soft black material the plain impression of the three
wheels. They came to a sudden stop before “the jumping-off place,” as
Jerry called it, was reached.
“Here’s where they sailed into the air,” he declared confidently.
“Let’s see if we can find where they landed,” suggested Ned.
They did, at the opposite end of the row of roofs, just where a tall
building reared itself several stories higher than the row of low
structures.
“They came down here all right,” declared Jerry excitedly pointing to
the deep impression made by the wheels. The boys even found the place
where the drag-brake had scraped a long line in the gravel, and that,
to them, made their “case complete.”
Suddenly the merchant’s son uttered a cry, and straightened up.
“What’s the matter?” asked Jerry in surprise.
“Those wheel marks!” gasped Ned. “Look! Those are new tires, Jerry. Not
worn a bit, and they’re the anti-skid style--see the corrugations and
the rubber-protruding cleats.”
“I see ’em--what of it?”
“Don’t you remember--Noddy Nixon’s aeroplane--after he put on the new
wheels, following his smash-up? Don’t you remember? He had wheels just
like these--exactly like them. Look!”
Jerry glanced at his chum with wide-opened eyes. Then he looked down at
the marks. The light of remembrance came into his eyes.
“By Jove, Ned, you’re right!” he exclaimed. “Noddy Nixon and Bill
Berry--and that talk I overheard between them--Noddy Nixon--his
aeroplane--I----”
At that moment Detective Blake, followed by President Carter of the
looted bank, and several of the directors, came out on the roof.