In fact, the nature of the wound strongly suggests that it was made by a round-headed, flat-bladed weapon, such as an ordinary table or dinner knife.

The thrust was made horizontally,--that is, across the ribs and between them, instead of perpendicularly, which is the usual method of stabbing.

Apparently the murderer realised that his knife was too broad for the purpose, and turned it the other way, so as to make sure of penetrating the ribs and reaching the heart." "Does not that suggest a rather unusual knowledge of human anatomy on the murderer's part ?" asked Mr.Cromering.
"I do not think so.

Anybody can tell how far apart the human ribs are by feeling them." "It is easy to see, Sir Henry, that the wound was made by a thin-bladed knife, but why do you think it was also round-headed ?" asked Superintendent Galloway.

"Might it not have been a sharp-pointed one ?" "Or even a dagger ?" suggested Mr.Cromering.
"Certainly not a dagger.