Up until recently, Czeladź (Silesia, Poland) was generally believed to have been an “open” city, with no stone or brick fortifications. This belief persisted due to lack of historical sources from the period and insufficient archaeological research. In 2016, the authors of this article carried out archaeological investigations 70 m east of the Market Square. The investigations led to the discovery of two wall remains. The width of the first one was 1.40 m. The wall was built from stones of various sizes, hewn only on the face side. The wall was added to another wall, 0.60 m wide at the foundation; however, the second wall was sunk into a compact layer of marl and clay, which reinforced it from its inner side. It was over 0.80 m wide, 2.07 m long and was preserved up to a height of 0.47 m. Five layers of stone have survived. Two fragments of earthenware were discovered in the fill of this cut, dated to, respectively, between the 15th/16th centuries and the 16th century. A lime and sand mortar was used in the construction of both walls. This mortar is characterized by a grey and beige colouration and admixture of significant amounts of sand, limestone lumps, small brick fragments and charcoals. Such admixtures were used in the Medieval Period, and date the mortar to the 14th/15th century. Through architectural and cartographic analysis it can be said that these wall remains are remnants of an element of city fortifications, namely a city wall and a fragment of the eastern city gate. The opening of the presumed gate lies on the same axis as the exit from Rynkowa Street. The investigations provided further evidence for the fact that Czeladź had defensive walls. The research also proved, for the first time in source archaeological material, the existence of a city gate.
Numerical Investigation of the Hydrodynamic Performance of the Propeller Behind the Ship with and Without Wed
