e engineer was not yet arrested, and, so far
indeed, there had been no statement in print to indicate that the police
were on his track. At last, however, Pierre one morning read a paragraph
which made the injured man turn pale.

"Dear me! It seems that a tool has been found among the rubbish at the
entrance of the Duvillard mansion. It is a bradawl, and its handle bears
the name of Grandidier, which is that of a man who keeps some well-known
metal works. He is to appear before the investigating magistrate to-day."

Guillaume made a gesture of despair. "Ah!" said he, "they are on the
right track at last. That tool must certainly have been dropped by
Salvat. He worked at Grandidier's before he came to me for a few days.
And from Grandidier they will learn all that they need to know in order
to follow the scent."

Pierre then remembered that he had heard the Grandidier factory mentioned
at Montmartre. Guillaume's eldest son, Thomas, had served his
apprenticeship there, and even worked there occasionally nowadays.

"You told me," resumed Guillaume, "that during my absence Thomas intended
to go back to the factory. It's in connection with a new motor which he's
planning, and has almost hit upon. If there should be a perquisition
there, he may be questioned, and may refuse to answer, in order to guard
his secret. So he ought to be warned of this, warned at once!"

Without trying to extract any more precise statement from his brother,
Pierre obligingly offered his services. "If you like," said he, "I will
go to see Thomas this afternoon. Perhaps I may come across Monsieur
Grandidier himself and learn how far the affair has gone, and what was
said at the investigating magistrate's."

With a moist glance and an affectionate grasp of the hand, Guillaume at
once thanked Pierre: "Yes, yes, brother, go there, it will be good and
brave of you."

"Besides," continued the priest, "I really wanted to go to Montmartre
to-day. I haven't told you so, but something has been worrying me. If
Salvat has fled, he must have left the woman and the child all alone up
yonder. On the morning of the day when the explosion took place I saw the
poor creatures in such a state of destitution, such misery, that I can't
think of them without a heart-pang. Women and children so often die of
hunger when the man is no longer there."

At this, Guillaume, who had kept Pierre's hand in his own, pressed it
more tightly, and in a trembling voice exclaimed