The Long Wall
Before dawn, a thin layer of morning mist rose over the sea. The mist was not thick, floating close to the water's surface. From the bow of the ship, one could see the upper edge of the horizontal structure, which gradually changed from a blurry dark line to a clearly defined gray outline as the sky grew brighter. Long Tian squatted at the bow, his coat collar still turned up, his gaze fixed on the direction of that outline.
After sunrise, the fog mostly dissipated. The structure revealed its complete surface in the morning light—it was indeed the top of a long wall, its surface flat, extending from the bow of the ship to both sides, narrowing into a thin line at the edge of the field of vision without interruption. The wall was about ten feet wide, covered with a thin layer of sediment, but the sediment was unevenly distributed, with some areas covered more thickly and others revealing the dark gray to black stone base beneath. In the center of the top of the wall was a longitudinal ridge, like a slender ridge embedded in the wall, extending straight along the entire length of the wall without bends or breaks.
The people at the stern reeled in the anchor, allowing the boat to slowly move along the top of the wall for a short distance. Long Tian squatted by the gunwale, observing the wall surface for seams and openings as the boat passed it. He confirmed that the sediment cover on the top of the wall remained continuous in most areas, without any obvious openings or gaps. After the boat had moved about half a mile along the top of the wall, the color of the wall began to darken slightly in one spot, as if the thickness of the cover had increased, forming a continuous section with a more pronounced color difference than the surrounding area.
He stopped the boat where the color difference deepened. He disembarked and walked a few steps along the wall surface. The wall surface presented a uniform gray tone in the morning light, maintaining a stable reflectivity under continuous sunlight. He walked along the ridge of the wall for a while, stopped at the spot where the color difference deepened, and squatted down to place his palm on the wall surface. The aura of the Origin Return Pearl spread along the wall surface. When it touched the edge of the area with the deepened color difference, the speed of the aura's transmission was slightly slower than in the surrounding area, as if the covering layer there was thicker, forming an extra buffer.
He focused the Dragon Shadow's light layer above the area of color difference, directing it vertically onto the wall surface. Under the concentrated light, the outline of that area began to show an edge different from natural sedimentation—it didn't resemble the sedimentation formed by uneven erosion by water flow, but rather had a neater edge, like a uniformly applied sealant. He traced the edge of that area with his palm, confirming that its overall outline was a rectangular area about an arm's width and half an arm's length.
He channeled the energy of the Origin Return Pearl into the center of that rectangular area, continuing the flow for about the time it takes to brew a cup of tea, allowing the energy to gradually seep through the covering layer and into the surface of the underlying stone base. The moment the energy penetrated the base surface, the edge of that rectangular area began to loosen segment by segment along its outline, as if the adhesive structure of the sealing layer was being continuously loosened by the energy. After the sealing layer loosened, it lifted up from the base surface as a whole, revealing a shallow horizontal groove underneath. The width of the groove was consistent with the spacing of the teeth on the edge of the Dragon Bone Marker Disc, and its direction was perpendicular to the ridgeline of the wall.
Yu Jin jumped off the ship and onto the top of the wall, then squatted down next to Long Tian. He observed the width and direction of the shallow groove for a while, then stood up and walked forward along its direction. He squatted down at another spot on the wall, scratched the surface with his fingertip, then stood up again and walked back to Long Tian, saying, "There's another similar shallow groove ahead, with the same spacing as the horizontal intervals on the top of the wall. It's as if there's a horizontal shallow groove of the same width along the top of the wall at regular intervals, like some kind of locking or fixing mechanism, evenly distributed along the entire wall, with the same spacing and depth at each location."
Long Tian squatted beside the shallow trench that had already been cleared, channeling the energy of the Origin Return Pearl into its depths, allowing it to travel around the bottom of the trench. The energy encountered no resistance at the bottom, smoothly traversing the entire depth before returning to his palm along the trench wall. He withdrew his hand, stood up, and took a few steps forward along the top of the wall. At the next pre-determined location, he squatted down and cleared away the surface sediment, revealing a shallow trench of the same size and depth as the first one.
The two men cleaned five shallow grooves along the top of the wall, each one perfectly aligned in position and size. After cleaning the fifth groove, Long Tian stood up, glanced at the wall's extension in the distance, and calculated the total number of grooves the wall might contain based on their spacing, confirming that the number was within an acceptable range. He returned to the ship, squatted down in the cabin, unfolded the silk map, and drew a horizontal line at the corresponding location on the top of the wall, marking the positions of the cleaned grooves proportionally on that line.
After he finished drawing the map, the person at the stern asked, "Is the direction of this wall the same as the direction of the extended line on the light screen map?"
Long Tian compared the horizontal line on the top of the wall on the map with the angle of the extended line on the light screen map. The deviation between the two was very small, almost overlapping. He put away the map, stood up and walked to the bow of the ship, looking at the direction in which the horizontal structure continued to extend in the morning light. It stretched continuously in his field of vision, without interruption or turning, like a long ruler built on the sea level, pointing straight to a distant end. He squatted down at the bow of the ship, adjusting the speed of the Origin Return Pearl and the new core to a continuous running state, so that the light layer of the Dragon Shadow was stably lit above the bow of the ship. Yu Jin sat down against the ship wall at the hatch, the light of the dark gray bead seeping out from his collar, maintaining a constant distance and brightness with the light layer of the Dragon Shadow, like two stable light sources fixed in the same painting, each occupying its own position.