Brief report on excavation of Linqing Gongzhuan site

The site is located on the right bank of the canal about 12km southeast of Linqing City, and the Beijing-Kowloon Railway passes through the west side of the site, belonging to the provincial cultural relics protection unit. The kiln site is concentrated along the river, starting from the west of Hejing Zhangzhuang Village, east to the northwest of Chenguanying Village, and stretching from east to west for about1500m. The nearest river is only fifty or sixty meters, and the farthest river is about 700 meters. Most of the kiln sites have been razed to the ground, and some of them still have mounds about 2-3 meters higher than the surrounding areas.

The structure of the kiln site is basically the same, consisting of a long trapezoidal inclined operating room, a fire door, a rectangular fire pool, a horseshoe-shaped or rectangular kiln room and a square chimney. The construction method is basically the same. Shallow pits at corresponding positions are dug on the original ground, walls are built with blue bricks around, and the bottom is paved with bricks. But it is poorly preserved, mostly only at the bottom, and the brick wall is destroyed. Some kiln rooms and workshops are still 1 m deep, and the worst is the sintering surface at the bottom of kiln room and chimney, but the shape and scale of kiln site are different in different periods.

There are 2 kiln sites in Ming Dynasty. Located in the north of the excavation area, two kilns are juxtaposed. The operation room faces east, showing a rectangular inclined pit, with single brick walls on both sides, and only the bottom wall foundation is left in some areas, with a width of about 2.28-2.6m and a length of about 5-6m. The depth of the fire pit is a horizontal rectangle.

The pit connected to the operation room in the east is about 2.5m in inner diameter, 0.8m in depth and 0.9m in depth. The fire door is located between the fire pit and the operation room and has been damaged. The kiln chamber is nearly horseshoe-shaped, with an inner diameter of 5.6-6.5m and a depth of1.9-2.6m.. The wall is a single brick structure, and there are still 4-5 layers of bricks in some areas. Bricks are mostly covered on one side, which can be distinguished by "the kiln that entered the factory in the five years of the apocalypse advocates one algae", and the bottom is covered with small bricks, which are arranged in parallel. Three square chimneys are equidistantly distributed at the back of the kiln room, and both sides of the chimneys extend symmetrically. Two bricks were erected between the chimney and the kiln room to separate three flues.

There are 16 kiln sites in Qing dynasty. There are two kinds of kiln chamber shapes: nearly square and rounded flat rectangle.

Square kiln houses are all located in the east of the excavation area, and the north and south are juxtaposed in five rows. The operation room faces northwest, the kiln room is nearly square, the rectangular fire pit extends into the kiln room, and two square chimneys are built at the back of the kiln room. Both were seriously damaged, and the walls and bottom bricks were removed. The kiln room is quite large, with an inner diameter of 4.2-4.9 meters wide and a depth of 4.6-5.2 meters. The kiln sites of circular flat rectangular kiln houses are mainly distributed on the east and west sides of the excavation area. Most of the factories on the east side face northwest, and some face southeast. The workshops on the west side all face southeast. At the back of the kiln room, there are three square chimneys made of bricks at equal intervals, and two bricks are erected between the chimneys and the kiln room to separate three flues. The preservation situation is very different. The east row was seriously damaged, and the bricks on the wall, bottom and both sides of the operation room were basically taken away. Only two in the west are well preserved. Brick walls with a height of 0.5- 1 m are left in some parts of the kiln house and workshop, and the floor tiles are well preserved. The scale varies. The indoor diameter of Dazhe kiln is about 7.8 meters wide and 4.3 meters deep. The workshop is 8.8-9.4m long, with an inner diameter of1.5m and a length of16-18m. The indoor diameter of Xiaozhe kiln is about 6.5 meters wide and 2.7 meters deep, the workshop is 5.2 meters long, the inner diameter is 1.4 meters, and the total length is 9.5 meters.

Two roads were also found, among which 1 had obvious rutting marks and extended into the river channel, which may be related to the outward transportation of bricks. However, after drilling, no pier remains were found at the junction of the road and the existing river course, which may be caused by mechanical dredging. In addition, the remains of borrow pit, garbage pit, ash storage pit, local active surface and a section of levee on the right side were cleared.

Cultural relics are mainly a large number of blue-gray bricks, of which 100 pieces are intact and stamped with inscriptions, and hundreds of pieces have inscriptions. The format and content of the inscription are the same, and they are all rectangular and single-frame single-line regular script, including the year, the name of the kiln owner and the person in charge, but the position and content of the inscription have changed in different times. Inscriptions in the Ming Dynasty were all printed on the long side of the brick, and the characters were written in Yang style. It is found that there are remnants of "Wanli" year, the rest are "the first year of the apocalypse, three years or five years", and the kiln owner is "Wangdian". The complete inscription reads as follows: "Wang Dian, the kiln owner who entered the factory in the fifth year of the Apocalypse, was the first volunteer". Brick carvings in Qing dynasty were carved on the end face, mostly in yangwen regular script, and a few in yinwen regular script, which spanned generations of Shunzhi, Kangxi, Yongzheng, Qianlong and Daoguang. Complete and clear are Meng Shouke, owner of Linqing kiln in the 15th year of Qing Kangxi, Cui, owner of Linqing brick kiln in the 9th year of Qing Qianlong, Cui Chengzao, owner of Linqing kiln in the 42nd year of Qing Qianlong, and Cui Guizao, a brick kiln worker in the 10th year of Qing Daoguang. We also found several bricks with red seals. The marks are located on the long sides of the bricks, and a line of six-character red regular script is printed in a rectangular red thick frame. The font is large, and the handwriting can be clearly identified as "Linqing Brick of Dongchangfu", with an inscription on the corresponding side, and the calendar year is nine years of Qianlong. In addition, a small number of fragments of household appliances such as blue-and-white porcelain bowls, plates and yellow-green glazed red pottery pots were found.

Judging from the unearthed inscription bricks, most of the kiln sites belong to Kangxi and Qianlong years, some should be earlier than the apocalypse years, and the latest belongs to Daoguang years.

According to Records of Ming and Qing Dynasties and Records of Linqing Prefecture, at the beginning of Yongle, the Ministry of Industry and Information Technology set up a maintenance department in Linqing to supervise the brick burning industry. At the age of one million, he was laid off in the eighteenth year of Shunzhi, and was appointed by the Governor of Shandong Province. Up to now, the symbol of Linqing brick has been found in royal buildings such as the Forbidden City, the Temple of Heaven, the Ming Tombs and the Qing Xiling Mausoleum. Linqing became the main base of royal building bricks in Ming and Qing dynasties, and the brick kiln factory in Linqing was also called "official kiln" locally. Although there are many records of Linqing bricks in Ming and Qing history books, they are only a few words, mainly related to the management of kiln factories. This excavation is the first large-scale exposure of the brick-burning "official kiln" site in the Ming and Qing Dynasties, which makes the tribute brick "official kiln" full of many mysterious colors reappear in the world since the Ming and Qing Dynasties, and fills the gaps in the record of kiln site shape, structure and kiln factory scale with rich physical materials. This will greatly promote the research on the firing techniques of tribute bricks in Ming and Qing dynasties, which is a national intangible cultural heritage, and also provide important physical materials for the in-depth study of canal culture and the application for the Grand Canal.