Skulking through the silent, deserted streets go men at war with society, men living by crime, who under the cover of darkness ply their perilous trade, ready armed to kill if need be, either the sleeping householder or the guardian of the night who interrupts them at their villainous work.

Sometimes they have accomplished their task and are returning to their homes with the spoil upon them, but so cunningly concealed that they can pass the policeman strolling on his lonely beat without exciting his suspicion.

For these men—the professional burglars who follow crime as a craft—plan and plot beforehand with the strategical skill of a general arranging an attack upon the enemy. After they have studied the "crib" they intend to "crack," and ascertained the habits of its inmates, they frequently walk the route they intend to follow once or twice beforehand in the night, noting everything by the way.

If you study the details of famous burglaries that have been brought home to their authors, you will find that the men concerned have made elaborate calculations, not only of the means of access, but of the position of the moon—the "Oliver" of the highwayman of the days of the romance of the road. "Shall we do it to-night?" is frequently the question asked when the accomplices meet to confer. They know what they mean to do, and the discussion is only as to whether the conditions are favourable. And one of the conditions to be considered is whether the dead of night is likely to be dark or bright.

Most of these men are known to the police, and many of them are "under observation." Millsom and Fowler were being watched by special instructions from Scotland Yard all through January and right up to the time they committed the burglary and murder at Muswell Hill. The burglars knew this so well that after the crime they hid in Highgate Wood until between five and six in the morning, and then started to walk home, thinking, in the words of Millsom's confession, "that at that time the police would be fairly scarce."

Then they walked from Muswell Hill through Kilburn to North Kensington, with the proceeds of the crime upon them.

Fowler's clothes were covered with blood-stains. To hide them he wore Millsom's brown overcoat. Though they were watched and wanted men, they walked through London reeking from their crime without attracting attention, because they had timed their return for the quietest part of the night.

The early hours from two to four are the burglar's hours for business; the hour for the walk home is later, that criminals returning from work may be mistaken for honest men going to it.

But there is romance in the dead of night, and the mystery of the world's work as well as of dark deeds.

London, the mighty city, slumbers not nor sleeps. In the darkest hours of the night the work is going forward for the needs of the great city, that will presently wake to another day of life.