Mr. Roberts threw a glance at it and straightened again.

“Explain yourself,” said he.  “I am quite at your service.”

The District Attorney made, perhaps, one of the greatest efforts of his life.

“I see that you recognize this chart, Mr. Roberts.  You know when it was made and why.  But what you may not know is this:  that in serving its original purpose, it has proved to be our guide in another of equal, if not greater, importance.  For instance, it shows us quite plainly who of all the persons present at the time of first alarm were near enough to the Curator’s office to be in the line of escape from the particularly secluded spot from which the arrow was delivered.  Of these persons, only one fulfills all other necessary conditions with an exactness which excuses any special interest we may feel in him.  It is he who is tabulated here as number 3.”

It was said.  Mr. Roberts was well acquainted with his own number.  He did not have to follow with his eye the point of the District Attorney’s finger to know upon whose name it had settled; and for a moment, surprise, shock,—­the greatest which can befall a man,—­struggled with countless other emotions in his usually impassive countenance.  Then he regained his poise, and with a curiously sarcastic smile such as his lips had seldom shown, he coldly asked: 

“And by what stretch of probability do you pick me out for this attack?  There were other men and women in this court, some very near me if I remember rightly.  In what are their characters superior, or their claims to respect greater, that you should thus single me out as the fool or knave who could not only commit so wild and despicable an act, but go so far in folly—­let alone knavery—­as to conceal it afterward?”

“No evidence has been found against the others you have named which could in any way connect them with this folly—­or shall we say knavery, since you yourself have made use of the word.  But hard as it is for me to say this, in a presence so highly esteemed, this is not true of you, Mr. Roberts, however high are our hopes that you will have such explanations ready as will relieve our minds from further doubts, and send us home rejoicing.  Shall I be frank in stating the precise reasons which seem to justify our present presumption?”

The director bowed, the same curious smile giving an unnatural expression to his mouth.

“Let me begin then,” the other continued, “by reading to you a list of questions made out at Headquarters, as a test by which suspicion might be conscientiously held or summarily dismissed.  They are few in number,” he added, as he unfolded a slip of paper taken from his vest pocket.  “But they are very vital, Mr. Roberts.  Here is the first: 

“‘Whose hand carried the bow from cellar to gallery?’”

The director remained silent; but the oppression of that silence was difficult for them all to endure.