“Tell me just how it happened that you got this bomb,” he asked.

Without hesitation, the Chinaman recited the circumstances, beginning with the note by which he had been summoned.

“A note?” repeated Kennedy, eagerly.  “Was it typewritten?”

Long Sin reached into his pocket and produced the note itself, which he had not burned.

As Craig studied the typewritten message from the Clutching Hand I could see that he was growing more and more excited.

“At last he has given us something typewritten,” he exclaimed.  “To most people, I suppose, it seems that typewriting is the best way to conceal identity.  But there are a thousand and one ways of identifying typewriting.  Clutching Hand knew that.  That was why he was so careful to order this note destroyed.  As for the bomb, he figured that it would destroy itself.”

He was placing one piece of typewriting after another under the lens, scrutinizing each letter closely.

“Look, Walter,” he remarked at length, taking a fine tipped pencil and pointing at the distinguishing marks as he talked, “You will notice that all the ‘T’s’ in this note are battered and faint as well as just a trifle out of alignment.  Now I will place the paper from the bomb under the lens and you will also see that the ‘T’s’ in the scrap of formula have exactly the same appearance.  That indicated, without the possibility of a doubt, taken in connection with a score of other peculiarities in the letters which I could pick out that both were written on the same typewriter.  I have selected the ‘T’ because it is the most marked.”

I strained my eyes to look.  Sure enough, Kennedy was right.  There was that unmistakable identity between the T’s in the formula and the note.

Kennedy had been gazing at the floor, his face puckered in thought as I looked.  Suddenly he slapped his hands together, as if he had made a great discovery.

“I’ve struck it!” he exclaimed, jumping up.  “I was wondering where I had seen typewriting that reminds me of this.  Walter, get on your coat and hat.  We are on the right trail at last.”

With Long Sin we hurried out of the laboratory, leaving him at the nearest taxicab stand, where we jumped into a waiting car.

“It is the clue of the battered ‘T’s,’” Craig muttered.

. . . . . . . .

Aunt Josephine was in the library knitting when the butler, Jennings, announced us.  We were admitted at once, for Aunt Josephine had never quite understood what was the trouble between Elaine and Craig, and had a high regard for him.

“Where is—­Miss Dodge?” inquired Kennedy, with suppressed excitement as we entered.

“I think she’s out shopping and I don’t know just when she will be back,” answered Aunt Josephine, with some surprise.  “Why?  Is it anything important—­any news?”

“Very important,” returned Kennedy excitedly.  “I think I have the best clue yet.  Only—­it will be necessary to look through some of the household correspondence immediately to see whether there are certain letters.  I wouldn’t be surprised if she had some—­perhaps not very personal—­but I must see them.”