erfect," he said, as he replaced the cap and closed the shutter.

He reversed the dark slide and made another exposure in the same way,
and then, having removed the micrometer and replaced it by a slip of
plain glass, he made two more exposures.

"There are two plates left," he remarked, as he drew out the second dark
slide. "I think I will take a record of the blood-stain on them."

He accordingly made two more exposures--one of the larger blood-stain
and one of the smaller smears.

"There," said he, with an air of satisfaction, as he proceeded to pack
up what the inspector described as his "box of tricks." "I think we have
all the data that we can squeeze out of Scotland Yard, and I am very
much obliged to you, Mr. Singleton, for giving so many facilities to
your natural enemy, the counsel for the defence."

"Not our natural enemies, doctor," protested Mr. Singleton. "We work for
a conviction, of course, but we don't throw obstacles in the way of the
defence. You know that perfectly well."

"Of course I do, my dear sir," replied Thorndyke, shaking the official
by the hand. "Haven't I benefited by your help a score of times? But I
am greatly obliged all the same. Good-bye."

"Good-bye, doctor. I wish you luck, though I fear you will find it 'no
go' this time."

"We shall see," replied Thorndyke, and with a friendly wave of the hand
to the inspector he caught up the two cases and led the way out of the
building.

CHAPTER IV

CONFIDENCES

During our walk home my friend was unusually thoughtful and silent, and
his face bore a look of concentration under which I thought I could
detect, in spite of his habitually impassive expression, a certain
suppressed excitement of a not entirely unpleasurable kind. I forbore,
however, from making any remarks or asking questions, not only because I
saw that he was preoccupied, but also because, from my knowledge of the
man, I judged that he would consider it his duty to keep his own counsel
and to make no unnecessary confidences even to me.

On our arrival at his chambers he immediately handed over the camera to
Polton with a few curt directions as to the development of the plates,
and, lunch being already prepared, we sat down at the table without
delay.

We had proceeded with our meal in silence for some time when Thorndyke
suddenly laid down his knife and fork and looked into my face with a
smile of quiet amusement.

"It has just been borne in upon me, Jervi