Twenty minutes later a dark and muffled figure was seen to emerge from a recess in the mullioned wall of the Arc de Triomphe and pass rapidly northward.
It was no other than Tictocq, the detective.
The network of evidence was fast being drawn about the murderer of Marie Cusheau.
It is midnight on the steeple of the Cathedral of Notadam.
It is also the same time at other given points in the vicinity.
The spire of the Cathedral is 20,000 feet above the pavement, and a casual observer, by making a rapid mathematical calculation, would have readily perceived that this Cathedral is, at least, double the height of others that measure only 10,000 feet.
At the summit of the spire there is a little wooden platform on which there is room for but one man to stand.
Crouching on this precarious footing, which swayed, dizzily with every breeze that blew, was a man closely muffled, and disguised as a wholesale grocer.
Old François Beongfallong, the great astronomer, who is studying the sidereal spheres from his attic window in the Rue de Bologny, shudders as he turns his telescope upon the solitary figure upon the spire.