The Dog-Bark Line

There is an invisible line in the gully. Up to it the dog still follows; the moment you cross, the dog turns and runs and will not come back however you call. No physical marker can be found on the line, and yet it cuts the gully cleanly into two worlds.

The bronze mirror shows it. Turn the mirror face slowly against empty air and the reflected patch of light leaves the rock wall and the ground, drifts to a point in midair and stops there, and however you turn it the patch comes back to the same place. Raise the compass to that height and the needle jumps 40 degrees counterclockwise; move 50 centimeters outward and it drops back to the faint tremor of 1 to 2 degrees; move back in and it is 40 degrees again. Checked once on each of 3 vertical axes, the readings agree:

Zone of abrupt change in field density, vertical, three-axis verification consistent.
Height range roughly 1.8 meters to 3 meters, boundary width estimated under 10 centimeters.
Shape unconfirmed — may run together into one sheet, may be vertical curtains set side by side.
Visible to the mirror, measurable by the compass, invisible to the naked eye.

Blow smoke at it and the smoke hangs at that point without moving; step aside and blow again and it disperses the way smoke does. Throw a paper ball across the line and its path shifts 3 centimeters, and it feels 3 degrees colder when you pick it up. Put a hand in and there is no resistance, only a sensation like the spreading of ripples traveling up along the skin.

On the far side of the line the rules are a different set. With the lamps off there is still brightness in the air, its color temperature like four or five in the afternoon, which does not square with the morning on the watch; shadows fall 70 degrees off the direction they should; walk 5 paces in and look back and the man outside the line seems 50 meters away. Sound does not cross — you can see his mouth open and hear nothing of it. In the instant of crossing, the watch jumped forward by about 1 hour.

Whom the rules take hold of is not consistent either. On the same line, Shen Zhaoye's shadow shifted 70 degrees when he crossed, and He Sanjin's did not shift at all.

People in the trade say that once you are past a line like that, you had better not count on anyone outside hearing you shout for help.