It was
inexplicable, but it was certain. “Why should he do it?” I asked. “Precisely what I should wish to ask you. If he had any such misgivings,
why could he not come and tell me direct?”

“Will you speak to him about it?”

“There again I am in doubt. He might choose to deny that he wrote it.”

“At any rate,” said I, “this warning is meant in a friendly spirit, and
I should certainly act upon it. Are the present precautions enough to
insure you against robbery?”

“I should have thought so. The public are only admitted from ten till
five, and there is a guardian to every two rooms. He stands at the door
between them, and so commands them both.”

“But at night?”

“When the public are gone, we at once put up the great iron shutters,
which are absolutely burglar-proof. The watchman is a capable fellow. He
sits in the lodge, but he walks round every three hours. We keep one
electric light burning in each room all night.”

“It is difficult to suggest anything more—short of keeping your day
watchers all night.”

“We could not afford that.”

“At least, I should communicate with the police, and have a special
constable put on outside in Belmore Street,” said I. “As to the letter,
if the writer wishes to be anonymous, I think he has a right to remain
so. We must trust to the future to show some reason for the curious
course which he has adopted.”

So we dismissed the subject, but all that night after my return to my
chambers I was puzzling my brain as to what possible motive Professor
Andreas could have for writing an anonymous warning letter to his
successor—for that the writing was his was as certain to me as if I had
seen him actually doing it. He foresaw some danger to the collection. Was it because he foresaw it that he abandoned his charge of it? But if
so, why should he hesitate to warn Mortimer in his own name? I puzzled
and puzzled until at last I fell into a troubled sleep, which carried me
beyond my usual hour of rising. I was aroused in a singular and effective method, for about nine o’clock
my friend Mortimer rushed into my room with an expression of
consternation upon his face. He was usually one of the most tidy men of
my acquaintance, but now his collar was undone at one end, his tie was
flying, and his hat at the back of his head. I read his whole story in
his frantic eyes. “The museum has been robbed!” I cried, springing up in bed. “I fear so! Those jewels! The jewels of the urim and thummim!” he
gasped, for he was out of breath with running. “I’m going on to the
police-station. Come to the museum as soon as you can, Jackson! Good-bye!” He rushed distractedly out of the room, and I heard him
clatter down the stairs. I was not long in following his directions, but I found when I arrived
that he had already returned with a police inspector, and another
elderly gentleman, who proved to be Mr. Purvis, one of the partners of
Morson and Company, the well-known diamond merchants. As an expert in
stones he was always prepared to advise the police. They were grouped
round the case in which the breastplate of the Jewish priest had been
exposed. The plate had been taken out and laid upon the glass top of the
case, and the three heads were bent over it. “It is obvious that it has been tampered with,” said Mortimer. “It
caught my eye the moment that I passed through the room this morning. I
examined it yesterday evening, so that it is certain that this has
happened during the night.”

It was, as he had said, obvious that some one had been at work upon it. The settings of the uppermost row of four stones—the carnelian, peridot,
emerald, and ruby-were rough and jagged as if some one had scraped all
round them. The stones were in their places, but the beautiful gold-work
which we had admired only a few days before had been very clumsily
pulled about. “It looks to me,” said the police inspector, “as if some one had been
trying to take out the stones.”

“My fear is,” said Mortimer, “that he not only tried, but succeeded. I
believe these four stones to be skilful imitations which have been put
in the place of the originals.”

The same suspicion had evidently been in the mind of the expert, for he
had been carefully examining the four stones with the aid of a lens. He
now submitted them to several tests, and finally turned cheerfully to
Mortimer. “I congratulate you, sir,” said he, heartily. “I will pledge my
reputation that all four of these stones are genuine, and of a most
unusual degree of purity.”

The colour began to come back to my poor friend’s frightened face, and
he drew a long breath of relief. “Thank God!” he cried. “Then what in the world did the thief want?”

“Probably he meant to take the stones, but was interrupted.”

“In that case one would expect him to take them out one at a time, but
the setting of each of these has been loosened, and yet the stones are
all here.”

“It is certainly most extraordinary,” said the inspector. “I never
remember a case like it. Let us see the watchman.”

The commissionaire was called—a soldierly, honest-faced man, who seemed
as concerned as Ward Mortimer at the incident. “No, sir, I never heard a sound,” he answered, in reply to the questions
of the inspector. “I made my rounds four times, as usual, but I saw
nothing suspicious. I’ve been in my position ten years, but nothing of
the kind has ever occurred before.”

“No thief could have come through the windows?”

“Impossible, sir.”

“Or passed you at the door?”

“No, sir; I never left my post except when I walked my rounds.”

“What other openings are there in the museum?”

“There is the door into Mr. Ward Mortimer’s private rooms.”

“That is locked at night,” my friend explained, “and in order to reach
it any one from the street would have to open the outside door as well.”

“Your servants?”

“Their quarters are entirely separate.”

“Well, well,” said the inspector, “this is certainly very obscure. However, there has been no harm done, according to Mr. Purvis.”

“I will swear that those stones are genuine.”

“So that the case appears to be merely one of malicious damage. But none
the less, I should be very glad to go carefully round the premises, and
to see if we can find any trace to show us who your visitor may have
been.”

His investigation, which lasted all the morning was careful and
intelligent, but it led in the end to nothing. He pointed out to us that
there were two possible entrances to the museum which we had not
considered. The one was from the cellars by a trap-door opening in the
passage. The other through a skylight from the lumber-room, overlooking
that very chamber to which the intruder had penetrated. As neither the
cellar nor the lumber-room could be entered unless the thief was already
within the locked doors, the matter was not of any practical importance,
and the dust of cellar and attic assured us that no one had used either
one or the other.