After Martin Hewitt had rushed off to St. Augustine's Hospital with the
key, the envelope, and the cypher I had brought him, I heard nothing of
him till dusk fell--about six. Then I received this telegram:--
/#
"Cypher read. Most interesting case. If you can spare an hour be
outside 120 Broad Street at six thirty.--<sc>Hewitt</sc>."
#/
I had to be at my office between eight and nine, and to keep Hewitt's
appointment I should probably have to sacrifice my dinner. But I was
particularly curious to know the meaning of that cypher, and just as
curious to know how it could be read; and, moreover, I knew that any
case that Hewitt called interesting would probably be interesting above
the common. So I took my hat and sought a cab.
I was first at the meeting-place--indeed, a little before my time. No.
120 Broad Street was a great new building of offices, most, if not all,
closed at this time--a fact indicated by the shutting of one of the
halves of the big front door, where a char-woman was sweeping the steps
under the board which announced that offices were to be let. I waited
nearly a quarter of an hour, and then at last a hansom stopped and
deposited Hewitt and another older gentleman before me.
"Hope we haven't kept you waiting, Brett," Hewitt said. "This is Mr.
Bell, of Kingsley, Bell and Dalton; it took me a little longer than I
expected to reach him. His offices are shut, and the clerks all gone,
but we are going to turn up the lights for a bit. The lift man is gone
too, I expect, so we shall have a good long stair-climb."
As to the lift man Hewitt was right, and during our long climb I
received, briefly, an account of the loss Mr. Bell's firm had suffered.
"I have told Mr. Bell," Hewitt said, "that it was you who happened
across the key in such an odd fashion, and when I wired I was sure he
would be glad to let you see the upshot of your strange bit of luck. I
was also pretty sure that you would like to see it, too. For I really
believe that this case--which I confess seemed pretty near hopeless a
few hours ago--is coming to an issue now, and here."
"Did you get any information out of the man in the hospital?" I asked.
"Not a scrap," Hewitt replied. "He was still insensible, and though I
saw his clothes, and they told me a good deal about the gentleman's
personal habits--which are not dazzlingly noble, to put it mildly--they
told me nothing else whatever, except that he had recently been knocked
down in the mud, which I knew already. But the cypher has told me
something, as I will explain presently."
By this time we had reached the high floor in which the offices stood,
and Mr. Bell, all wonder and pale agitation, unlocked the outer door,
and turned on the electric light.
"Now," cried Hewitt, "show me your ventilators!"
There were some, it seemed, in the top panes of the windows, but these
were not what Hewitt wanted. There were others in the form of upright
chambers or flues, made of metal, and painted the same colour as the
walls about them. They rose from the floor in corners and wall angles,
and could be shut or opened by means of lids over their upper ends.
These were more to Hewitt's mind, and he went about from one to another,
groping under the lids, and poking down into the flues with a
walking-stick. There was a wire-grating, or diaphragm, it seemed, in
each of them, two or three feet down, and we could hear the end of the
stick raking on this at each investigation. One after another of these
ventilators Hewitt examined, till he had examined them all, in outer and
inner rooms, without result; and I could see that he was disappointed.
"There must be another somewhere," he said, and hunted afresh.
But plainly he had tried them all, and now he could do no more than try
them all again, with as little result.
"It _is_ a ventilator," he said, positively. "Unless----" he broke off
thoughtfully and stood silent for a few moments. "Ah! of course!" he
resumed presently. "We'll send for the housekeeper and a candle. Which
is the nearest empty office--the nearest office to let? Is there one on
this floor?"
"I think not," Mr. Bell answered. "But there's one on the floor below,
just opposite the lift--I see the bill on the door every day as I come
up."
"We'll try that, then. I'll rake out every ventilator in this palatial
edifice before I'll call myself beaten. Come, call the housekeeper. Is
there a speaking tube? Tell him to bring a light."
The housekeeper came, wonderingly, with a watch-man's oil-lantern, and
we all went to the floor below. Opposite the lift was a glass door from
which a bill had recently been torn.
"Why, it's let!" said Mr. Bell.
"Yes, sir," assented the housekeeper. "Let a day or two ago to a Mr.
Catherton Hunt. Or, at least, a deposit was paid."
"But see--the door's not locked," Hewitt observed, pushing it open. "I
think we'll trespass on Mr. Catherton Hunt's new offices, since they
seem quite empty, and he hasn't taken possession. Come--ventilators!"
It was a small office--an outer room of moderate size, and one smaller
inner room. Hewitt at once attacked the ventilators in the larger
apartment--there were two of them--but retired disappointed from each.
There was one ventilator only in the small room. Hewitt tilted the lid,
which was at about the level of his eyes, thrust in his hand, and drew
forth a bundle of folded papers; thrust in his hand again and drew forth
another bundle; did it again, and drew forth more!
Mr. Bell fell upon the first bundle almost as a dog falls upon a bone;
and now he snatched eagerly at each successive paper or bundle, till
Hewitt raked the grating with his stick, and declared that there were no
more. "Is that all?" he asked.
Mr. Bell went tremblingly from paper to paper, and, at last, said that
he believed it really was. "I can verify it by the list upstairs," he
added, "if you are sure there are no more."
"No more," repeated Hewitt, rattling his stick in the ventilator again.
"Let us go and verify, by all means."
We sent the puzzled housekeeper away, and returned to the office above,
and presently Mr. Bell, now beginning so far to recover from his
amazement as to express incoherent gratitude, reported that the bonds
were correct and complete to the last and least.
"Very well," said Hewitt, "then my part of the business is done, though
I must say I've had luck, or rather, Brett has had it for me. But the
police must come on now. I think, Mr. Bell, we'll go along to Scotland
Yard when we leave here. They'll be wanting to see Mr. Catherton Hunt, I
expect, whoever he is--and somebody in your office, too, if I'm not
sadly mistaken."
"Who?" gasped Mr. Bell.
"That, perhaps, you can help to point out. See here--do you know whose
figures they are?" and Hewitt produced the small slip of paper
containing the cypher.
"They're very small," remarked Mr. Bell, putting on his glasses; "very
small indeed; but I think--why they're Henning's, I do believe!"
"Ah! one or two other little things seemed to point that way. Henning is
your correspondence clerk, I believe, and I expect this thin little slip
is a specimen of your typewriter paper. Have you any of his written
figures for comparison?"
"Well no--I hardly think--you see he typewrites his letters, and
although I know his writing very well I can't at the moment put my hand
on any figures of his."
"Never mind--it's mere matter of curiosity; the police will ask him
questions in the morning. What _I_ believe has happened is this. Our
friend Henning--if he's the man--has a friend outside a great deal
cleverer than himself--though he would seem to have his share of
cunning, too. Between them they resolved to rob you in the way they have
done--temporarily. Henning was to take advantage of his position in that
little inner room to get at the safe some day when it was open and when
you were engaged in your own private inner room with a client, so
leaving the safe unwatched. He was provided with a spare patent padlock
and key, of the sort you used on that black box, and his confederate had
drilled him in the trick of breaking that particular sort of padlock
open, with other spare specimens. He got his opportunity this morning."
"Only this morning?"
"This morning, I think, else we should never have got these bonds back,
nor even have heard of them again. I think you said you were engaged
with a client for half an hour?"
"Yes, from about half-past ten to eleven."
"That was his chance, and he took it. He broke the padlock, took out the
bonds, substituted the dummies he had already prepared in his own desk,
and locked the box again with the new padlock. Meantime Hunt had paid a
deposit, pending references, on the office below--the nearest empty
room. Of course, he wouldn't get the key until the tenancy was finally
accepted--which he never intended it should be. But he easily arranged
to have the door left unlocked for a day or two, on some convenient
excuse--arranging decorations, or what not. And the bill was taken down,
so that prospective and prospecting tenants were kept away. The bonds
being stolen, Henning took the first opportunity of carrying them to the
empty office--probably piecemeal--a thing he could easily manage almost
under your nose, before you were aware of your loss. There he was to
conceal them, either in the chimney, under the boards, or in the
ventilator, as he might find convenient--and he found the ventilator
most convenient. Then he was to apprise his confederate of the fact that
the robbery had been effected in order that Hunt might come and quietly
fetch the plunder away. The message was to take an ingenious form. Hunt
was to have a fellow waiting about in the street, and as soon as Henning
could get out--say to lunch--he was just to _send the key_ by this
messenger--the key with which he had locked the new padlock on the black
box. You see the advantages of that simple arrangement. First, the key,
which is evidence, is got rid of in a safe and effectual way--a thing
that couldn't be done as well by merely flinging it away on or near the
premises, where it might be found. Next, the message is perfectly
secret--the messenger could never guess what the key meant, nor could
any other person not in the confederate's confidence. And, at the same
time, the key tells all that is necessary; the robbery has been
effected--come and remove the plunder.
"But something unforeseen happens. No sooner are the bonds stolen and
safely hidden than you go to the box, find something wrong with the
lock, break it open and discover the loss. This was a thing that they
trusted would not happen till after the bonds were safely got away.
More, I am sent for, the clerks are kept in from lunch, and so on.
Henning gets into a funk, and resolves to send a message of special
urgency to his confederate. For that purpose he uses a cypher which the
two have agreed upon--the most ingenious cypher I have ever seen used
for the purpose. He doesn't wish to make his message any more
conspicuous than he need, so he writes his cypher on this scrap of paper
and rolls it inside the key--probably another expedient agreed upon in
case of necessity. Then the key goes into an envelope, for greater
security of the cypher message, and the messenger gets it when Henning
is at last released for lunch. What happened to the message we know; and
here it is.
"Now I will not weary you with a detailed account of the different ways
in which I attacked this cypher, but I will take the shortest possible
cut to the true interpretation. A very short examination of the
cryptogram shows that while no number is included above 23, the numbers,
in their relative frequency, roughly agree with the relative frequency
of the corresponding letters of the alphabet, _a_ for 1, _b_ for 2, and
so on."
Here I handed Hewitt the pencilled note I had made at the hospital, with
letters substituted for the figures, thus:--_i, h, n, d, t, r, e, i; o,
s, t, 0, c, i, h, e; c, w, 0, 0, e, m, n, s; s, t, 0, 0, 0, 0, f, a; e,
t, 0, 0, 0, 0, c, v; a, o, 0, 0, 0, 0, r, e; a, h, t, k, r, i, e, t; l,
e, w, n, n, a, a, t._
Hewitt took the paper and went on. "If that were all the thing would be
childishly simple. But you will see that we seem as far from the
solution as ever; for the letters as they stand mean nothing, though in
fact they are in normal relative frequency; so that if they mean other
letters, all the rules are upset, and we are at a standstill. I admit
that for a long time the thing bothered me. But a peculiarity struck me.
Not only were the figures, or letters, disposed in groups of _eight_,
but there were also _eight_ such groups--sixty-four altogether. What did
that suggest? What but a chessboard?"
"A chessboard?" I queried.
"Just so--a chessboard. Eight squares each way--sixty-four altogether.
So I drew a rough representation of a chessboard, and set out the
letters on it, in their order, like this:--
i h n d t r e i
o s t O c i h e
c w 0 0 e m n s
s t 0 o o 0 f a
e t 0 o o 0 c v
a o 0 o o 0 r e
a h t k r i e t
l e w n n a a t
"Now, there was my chessboard with my letters on it. I tried reading
them downward, across, upward and diagonally, in the direction of the
moves of different chess pieces--king, queen, rook and bishop. Nothing
came of that, whatever I did; the thing was as unreadable as ever. But
there remained one chess-move to try--the eccentric move of the knight;
the move of one square forward, backward or sideways, and then one
square diagonally, or, as it has sometimes been more concisely
expressed, the move to the next square but one of a different colour
from that on which it rests. I tried the knight's move, and I read the
cypher.
"I began at the top left-hand corner, just as one does in reading a
book. I read the moves downward--_i_ to _w_, _e_ and _h_, and found that
led to nothing. So I took the one alternative move, and, with a little
consideration, skipped along from _i_ to _t_ in the second line of
squares, _t_ in the top line, _h_ in the second line, _e_ in the third,
_r_ in the top and _e_ in the second. That gave me an idea. There were
the letters _i, t, t_, followed by the word _here_. I tried back
from the _i_ again, and taking in the reverse order the _w, e_ and _h_
which I had first given up, I read my own name, as you can see it, from
the _h_ on the bottom line but one, moving upward. So I had the words
_Hewitt here_. I need not carry you through all the steps, which will
now be plain enough to you. But I found that the message actually began
in the _right_-hand corner, and read thus, the noughts counting for
nothing--
"_'Invent loss disc take at once Martin Hewitt here fear watch.'_
"The noughts were plainly merely inserted to fill in unneeded squares,
and keep the rest of the figures in their proper relative places when
the cypher was written in line. At first I was a little puzzled to
understand what seemed to be the first word _invent_. But it was quite
clear that _loss disc_ meant 'loss discovered,' so I concluded that here
in the beginning was a contraction also, and that _in_ was a separate
word. In that case _vent_ could be a contraction for no other word but
'ventilator,' in accordance with the sense of the words. So I concluded
that the meaning of the whole sentence was simply this: 'The plunder is
in the ventilator, the loss is discovered, take away the booty at once;
Martin Hewitt is here, and I fear I may be watched.' There is the
reading, and our little adventure this evening is what it has led to.
"Of course, the confederate wouldn't go groping about the squares so
painfully as I have had to do. To him the reading would be simple
enough, for the order of the moves would be preconcerted. Each of the
conspirators would have, as a guide, both to reading and writing the
cypher, a drawn set of squares, numbered in the order of the moves--1
where we have the _i_, 2 where we have the _n_, 3 where we have the _v_,
and so on. With that before him, either reading or writing in this
extraordinary cryptogram would be easy and quick enough. And now for
Scotland Yard!"