Kuhna Ark - summer mosque (rear wall 3) - gp

Topic:
Geometry
The fundaments of the Kuhna Ark, the historical fortress of Khiva date from the 5th century, butr most of the buldings date from the 19th century. The summer mosque dates from 1838. The glazed tiles are created by two local masters: Ibadullah and Abdullah Jin, who also created the tiles of the Tash Hauli palace. Remarkable is that the walls of the iwan of the summer mosque completely are decorated with glazed tiles, but in different patterns.
Image
One of the patterns is a tiling of double bell shapes in a square grid.

construction

Left: You can draw the bell shapes starting from tangent circles. Right: You can draw the double bell shapes starting from the square grid. The basic rule of a tiling is that you can modify the sides of the square so that an extentions is equally compensated. A modification of one side can be transferred to another side by rotation or translation, forming the unit of the tiling.