The knowledge of this fact came in useful on one of my investigating tours.  Inside a great high wall lay a dockyard in which, it was rumoured, a new power-house was being erected, and possibly a dry dock was in course of preparation.

It was early morning; the gates were just opened; the workmen were beginning to arrive, and several carts of materials were waiting to come in.  Seizing the opportunity of the gates being open, I gave a hurried glance in, as any ordinary passer-by might do.  I was promptly ejected by the policeman on duty in the lodge.

I did not go far.  My intention was to get inside somehow and to see what I could.  I watched the first of the carts go in, and noticed that the policeman was busily engaged in talking to the leading wagoner, while the second began to pass through the gate.  In a moment I jumped alongside it on the side opposite to the janitor, and so passed in and continued to walk with the vehicle as it turned to the right and wound its way round the new building in course of construction.

I then noticed another policeman ahead of me and so I kept my position by the cart, readapting its cover in order to avoid him.  Unfortunately in rounding the corner I was spied by the first policeman, and he immediately began to shout to me (see map).  I was deaf to his remarks and walked on as unconcernedly as a guilty being could till I placed the corner of the new building between him and me.  Then I fairly hooked it along the back of the building and rounded the far corner of it.  As I did so I saw out of the tail of my eye that he was coming full speed after me and was calling policeman No. 2 to his aid.  I darted like a red-shank round the next corner out of sight of both policemen, and looked for a method of escape.

[Illustration:  The dotted line in this plan shows my route, small figures are policemen looking for me.]

The scaffolding of the new house towered above me, and a ladder led upwards on to it.  Up this I went like a lamplighter, keeping one eye on the corner of the building lest I should be followed.

I was half-way up when round the corner came one of the policemen.  I at once “froze.”  I was about fifteen feet above sea level and not twenty yards from him.  He stood undecided with his legs well apart, peering from side to side in every direction to see where I had gone, very anxious and shifty.  I was equally anxious but immovable.

Presently he drew nearer to the ladder and, strangely enough, I felt safer when he came below me, and he passed almost under me, looking in at the doorways of the unfinished building.  Then he doubtfully turned and looked back at a shed behind him, thinking I might have gone in there, and finally started off, and ran on round the next corner of the building.  The moment he disappeared I finished the rest of my run up the ladder and safely reached the platform of the scaffolding.