The Steamer's Rule

When all three Lights I see ahead,
I Port my helm, and show my RED.

GREEN to GREEN — or, RED to RED —
Perfect safety — Go ahead!

If to my starboard RED appear,
It is my duty to keep clear;
To act as judgment says is proper;
To Port — or Starboard — Back — or, Stop her!

But when upon my Port is seen
A Steamer's Starboard Light of GREEN,
There's nought for me to do but see
That GREEN to Port keeps clear of me.

Both in safety and in doubt,
I always keep a good look-out;
In danger, with no room to turn,
I Ease her — Stop her — Go astern!

By Mr. Thomas Gray 1873