The magic casket
had virtually admitted that the casket had told him something; and as
we walked up the Square to the gate in Lincoln’s Inn Fields, I watched
him furtively, trying to gather from his impassive face a hint as to
what the something amounted to, and wondering how the movements of the
fugitive bore on the solution of the mystery. Brodribb was similarly
occupied, and as we crossed from Great Turnstile and took our way up
Brownlow Street, I could see that his excitement was approaching
bursting-point.
At the top of the street Thorndyke paused and looked up and down the
rather dismal thoroughfare which forms a continuation of Bedford Row
and bears its name. Then he crossed to the paved island surrounding
the pump which stands in the middle of the road, and from thence
surveyed the entrances to Brownlow Street and Hand Court; and then he
turned and looked thoughtfully at the pump.
“A quaint old survivor, this,” he remarked, tapping the iron shell
with his knuckles. “There is a similar one, you may remember, in Queen
Square, and another at Aldgate. But that is still in use.”
“Yes,” Brodribb assented, almost dancing with impatience and inwardly
damning the pump, as I could see, “I’ve noticed it.”
“I suppose,” Thorndyke proceeded, in a reflective tone, “they had to
remove the handle. But it was rather a pity.”
“Perhaps it was,” growled Brodribb, whose complexion was rapidly
developing affinities to that of a pickled cabbage, “but what the
d----”
Here he broke off short and glared silently at Thorndyke, who had
raised his arm and squeezed his hand into the opening once occupied by
the handle. He groped in the interior with an expression of placid
interest, and presently reported: “The barrel is still there, and so,
apparently, is the plunger--” (Here I heard Brodribb mutter huskily,
“Damn the barrel and the plunger too!”) “but my hand is rather large
for the exploration. Would you, Miss Bonney, mind slipping your hand
in and telling me if I am right?”
We all gazed at Thorndyke in dismay, but in a moment Miss Bonney
recovered from her astonishment, and with a deprecating smile, half
shy, half amused, she slipped off her glove, and reaching up--it was
rather high for her--inserted her hand into the narrow slit. Brodribb
glared at her and gobbled like a turkey-cock, and I watched her with a
sudden suspicion that something was going to happen. Nor was I
mistaken. For, as I looked, the shy, puzzled smile faded from her face
and was succeeded by an expression of incredulous astonishment. Slowly
she withdrew her hand, and as it came out of the slit it dragged
something after it. I started forward, and by the light of the lamp
above the pump I could see that the object was a leather bag secured
by a string from which hung a broken seal.
“It can’t be!” she gasped as, with trembling fingers, she untied the
string. Then, as she peered into the open mouth, she uttered a little
cry.
“It is! It is! It is the necklace!”
Brodribb was speechless with amazement. So was I; and I was still
gazing open-mouthed at the bag in Miss Bonney’s hands when I felt
Thorndyke touch my arm. I turned quickly and found him offering me an
automatic pistol.
“Stand by, Jervis,” he said quietly, looking towards Gray’s Inn.
I looked in the same direction, and then perceived three men stealing
round the corner from Jockey’s Fields. Brodribb saw them, too, and
snatching the bag of pearls from his client’s hands, buttoned it into
his breast pocket and placed himself before its owner, grasping his
stick with a war-like air. The three men filed along the pavement
until they were opposite us, when they turned simultaneously and bore
down on the pump, each man, as I noticed, holding his right hand
behind him. In a moment, Thorndyke’s hand, grasping a pistol, flew
up--as did mine, also--and he called out sharply:
“Stop! If any man moves a hand, I fire.”
The challenge brought them up short, evidently unprepared for this
kind of reception. What would have happened next it is impossible to
guess. But at this moment a police whistle sounded and two constables
ran out from Hand Court. The whistle was instantly echoed from the
direction of Warwick Court, whence two more constabulary figures
appeared through the postern gate of Gray’s Inn. Our three attendants
hesitated but for an instant. Then, with one accord, they turned tail
and flew like the wind round into Jockey’s Fields, with the whole
posse of constables close on their heels.
“Remarkable coincidence,” said Brodribb, “that those policemen should
happen to be on the look-out. Or isn’t it a coincidence?”
“I telephoned to the station superintendent before I started,” replied
Thorndyke, “warning him of a possible breach of the peace at this
spot.”
Brodribb chuckled. “You’re a wonderful man, Thorndyke. You think of
everything. I wonder if the police will catch those fellows.”
“It is no concern of ours,” replied Thorndyke. “We’ve got the pearls,
and that finishes the business. There will be no more shadowing, in
any case.”
Miss Bonney heaved a comfortable little sigh and glanced gratefully at
Thorndyke. “You can have no idea what a relief that is!” she
exclaimed; “to say nothing of the treasure-trove.”
We waited some time, but as neither the fugitives nor the constables
reappeared, we presently made our way back down Brownlow Street. And
there it was that Brodribb had an inspiration.
“I’ll tell you what,” said he. “I will just pop these things in my
strong-room--they will be perfectly safe there until the bank opens
to-morrow--and then we’ll go and have a nice little dinner. I’ll pay
the piper.”
“Indeed you won’t!” exclaimed Miss Bonney. “This is my thanksgiving
festival, and the benevolent wizard shall be the guest of the
evening.”
“Very well, my dear,” agreed Brodribb. “I will pay and charge it to
the estate. But I stipulate that the benevolent wizard shall tell us
exactly what the oracle said. That is essential to the preservation of
my sanity.”
“You shall have his _ipsissima verba_,” Thorndyke promised; and the
resolution was carried, _nem. con._
An hour and a half later we were seated around a table in a private
room of a café to which Mr. Brodribb had conducted us. I may not
divulge its whereabouts, though I may, perhaps, hint that we
approached it by way of Wardour Street. At any rate, we had dined,
even to the fulfilment of Brodribb’s ideal, and coffee and liqueurs
furnished a sort of gastronomic doxology. Brodribb had lighted a cigar
and Thorndyke had produced a vicious-looking little black cheroot,
which he regarded fondly and then returned to its abiding-place as
unsuited to the present company.
“Now,” said Brodribb, watching Thorndyke fill his pipe (as understudy
of the cheroot aforesaid), “we are waiting to hear the words of the
oracle.”
“You shall hear them,” Thorndyke replied. “There were only five of
them. But first, there are certain introductory matters to be disposed
of. The solution of this problem is based on two well-known physical
facts, one metallurgical and the other optical.”
“Ha!” said Brodribb. “But you must temper the wind to the shorn lamb,
you know, Thorndyke. Miss Bonney and I are not scientists.”
“I will put the matter quite simply, but you must have the facts. The
first relates to the properties of malleable metals--excepting iron
and steel--and especially of copper and its alloys. If a plate of such
metal or alloy--say, bronze, for instance--is made red-hot and
quenched in water, it becomes quite soft and flexible--the reverse of
what happens in the case of iron. Now, if such a plate of softened
metal be placed on a steel anvil and hammered, it becomes extremely
hard and brittle.”
“I follow that,” said Brodribb.
“Then see what follows. If, instead of hammering the soft plate, you
put on it the edge of a blunt chisel and strike on that chisel a sharp
blow, you produce an indented line. Now the plate remains soft; but
the metal forming the indented line has been hammered and has become
hard. There is now a line of hard metal on the soft plate. Is that
clear?”
“Perfectly,” replied Brodribb; and Thorndyke accordingly continued:
“The second fact is this: If a beam of light falls on a polished
surface which reflects it, and if that surface is turned through a
given angle, the beam of light is deflected through double that
angle.”
“H’m!” grunted Brodribb. “Yes. No doubt. I hope we are not going to
get into any deeper waters, Thorndyke.”
“We are not,” replied the latter, smiling urbanely. “We are now going
to consider the application of these facts. Have you ever seen a
Japanese magic mirror?”
“Never; nor even heard of such a thing.”
“They are bronze mirrors, just like the ancient Greek or Etruscan
mirrors--which are probably ‘magic’ mirrors, too. A typical specimen
consists of a circular or oval plate of bronze, highly polished on the
face and decorated on the back with chased ornament--commonly a dragon
or some such device--and furnished with a handle. The ornament is, as
I have said, chased; that is to say, it is executed in indented lines
made with chasing tools, which are, in effect, small chisels, more or
less blunt, which are struck with a chasing-hammer.
“Now these mirrors have a very singular property. Although the face is
perfectly plain, as a mirror should be, yet, if a beam of sunlight is
caught on it and reflected, say, on to a white wall, the round or oval
patch of light on the wall is not a plain light patch. It shows quite
clearly the ornament on the back of the mirror.”
“But how extraordinary!” exclaimed Miss Bonney. “It sounds quite
incredible.”
“It does,” Thorndyke agreed. “And yet the explanation is quite simple.
Professor Sylvanus Thompson pointed it out years ago. It is based on
the facts which I have just stated to you. The artist who makes one of
these mirrors begins, naturally, by annealing the metal until it is
quite soft. Then he chases the design on the back, and this design
then shows slightly on the face. But he now grinds the face perfectly
flat with fine emery and water so that the traces of the design are
completely obliterated. Finally, he polishes the face with rouge on a
soft buff.
“But now observe that wherever the chasing-tool has made a line, the
metal is hardened right through, so that the design is in hard metal
on a soft matrix. But the hardened metal resists the wear of the
polishing buff more than the soft metal does. The result is that the
act of polishing causes the design to appear in faint relief on the
face. Its projection is infinitesimal--less than the
hundred-thousandth of an inch--and totally invisible to the eye. But,
minute as it is, owing to the optical law which I mentioned--which, in
effect, doubles the projection--it is enough to influence the
reflection of light. As a consequence, every chased line appears on
the patch of light as a dark line with a bright border, and so the
whole design is visible. I think that is quite clear.”
“Perfectly clear,” Miss Bonney and Brodribb agreed.
“But now,” pursued Thorndyke, “before we come to the casket, there is
a very curious corollary which I must mention. Supposing our artist,
having finished the mirror, should proceed with a scraper to erase the
design from the back; and on the blank, scraped surface to etch a new
design. The process of etching does not harden the metal, so the new
design does not appear on the reflection. But the old design would.
For although it was invisible on the face and had been erased from the
back, it would still exist in the substance of the metal and continue
to influence the reflection. The odd result would be that the design
which would be visible in the patch of light on the wall would be a
different one from that on the back of the mirror.