Beneath us now lies the vast and bottomless pool of the night sky. From the blue depths there comes pouring up, like the exhalations of some sinister sea creature in the primeval ooze, bubbles of green fire. Suddenly in the darkness appears a round bead of emerald light, another one appears beneath it, and then another, and a whole necklace pours upwards as though a string of gems had been pulled out of a fold in a black velvet cloth. In simple curves they soar past us into the upper sky, where perhaps they die out on their upward rush, or turn over and begin to drop downwards before they fade into mere red sparks falling swiftly. Now are we towering high over the black edge of the coast in the pinnacles of the slim searchlights which challenge us in front, and move to the right and left of us. We are conscious of our hostility to those below, and rejoice to creep unseen, unnoticed, across this sentinel barrier. Around us the occasional ropes of brilliant emeralds wander upwards in regularity and silence, and for a rare moment we are conscious of being in the air at night. To our left Zeebrugge flings into the sky a dozen beams of powerful light, fortunately too remote to challenge us. To our right Ostend echoes the threat. We are just between the two danger zones, unassailable, but by a short distance only, by both of them. I am learning the mistake of crossing the enemy's sea frontier instead of his land frontier. I am worried and harassed at the very beginning of my travel across his territory, instead of becoming settled down and used to being in an enemy sky before the visible danger of searchlights appear to challenge my passage. We pass slowly, silently, through the suspicious beams of light. To the right and left we twist and turn as one of the swords cuts the sky near us. I draw my arms to my side to make myself smaller so that I may wriggle through the sharp edges of danger without being touched. Apart from the risk it is exciting, though very nerve-trying. When at last we are through the barrier, and regain the undefended inland region, there is a great feeling of relief.