Kennedy’s laboratory was brightly lighted when I arrived early the next evening.  One by one his “guests” dropped in.  It was evident that they had little liking for the visit, but the coroner had sent out the “invitations,” and they had nothing to do but accept.  Each one was politely welcomed by the professor and assigned a seat, much as he would have done with a group of students.  The inspector and the coroner sat back a little.  Mrs. Parker, Mr. Downey, Mr. Bruce, myself, and Miss La Neige sat in that order in the very narrow and uncomfortable little armchairs used by the students during lectures.

At last Kennedy was ready to begin.  He took his position behind the long, flat-topped table which he used for his demonstrations before his classes.  “I realise, ladies and gentlemen,” he began formally, “that I am about to do a very unusual thing; but, as you all know, the police and the coroner have been completely baffled by this terrible mystery and have requested me to attempt to clear up at least certain points in it.  I will begin what I have to say by remarking that the tracing out of a crime like this differs in nothing, except as regards the subject-matter, from the search for a scientific truth.  The forcing of man’s secrets is like the forcing of nature’s secrets.  Both are pieces of detective work.  The methods employed in the detection of crime are, or rather should be, like the methods employed in the process of discovering scientific truth.  In a crime of this sort, two kinds of evidence need to be secured.  Circumstantial evidence must first be marshalled, and then a motive must be found.  I have been gathering facts.  But to omit motives and rest contented with mere facts would be inconclusive.  It would never convince anybody or convict anybody.  In other words, circumstantial evidence must first lead to a suspect, and then this suspect must prove equal to accounting for the facts.  It is my hope that each of you may contribute something that will be of service in arriving at the truth of this unfortunate incident.”

The tension was not relieved even when Kennedy stopped speaking and began to fuss with a little upright target which he set up at one end of his table.  We seemed to be seated over a powder magazine which threatened to explode at any moment.  I, at least, felt the tension so greatly that it was only after he had started speaking again, that I noticed that the target was composed of a thick layer of some putty-like material.

Holding a thirty-two-calibre pistol in his right hand and aiming it at the target, Kennedy picked up a large piece of coarse homespun from the table and held it loosely over the muzzle of the gun.  Then he fired.  The bullet tore through the cloth, sped through the air, and buried itself in the target.  With a knife he pried it out.

“I doubt if even the inspector himself could have told us that when an ordinary leaden bullet is shot through a woven fabric the weave of that fabric is in the majority of cases impressed on the bullet, sometimes clearly, sometimes faintly.”