Even when a post-mortem examination was made, the doctors were puzzled.

A threadlike solution of continuity was discovered in certain parts of his body, but it was lost in others, and the coroner's verdict was that he came to his death from unknown causes while descending a shaft.

The general opinion was that in some way or other he had been frightened to death.
This accident, much to Roland Clewe's chagrin, discovered to the public the existence of the great shaft.

Whether or not he would announce its existence himself, or whether he would close it up, had not been determined by Clewe; but when he and Margaret had talked over the matter soon after the terrible incident, his mind was made up beyond all possibility of change, and, by means of great bombs, the shaft was shattered and choked up for a depth of half a mile from its mouth.

When this work was accomplished, nothing remained but a shallow well, and, when this had been filled up with solid masonry, the place where the shaft had been was as substantial as any solid ground.
Now the great discovery was probably shut out forever from the world, but Clewe was well satisfied.