On the left of the way descending from the Brotschberg to the forrester house of the Schaeferplatz, you can find this vat of stone.
I could find nothing about this vat in all the books I could read. In order to find the vat itself in the forest, I had to ask my father and to look at his old maps of the Club Vosgien. On old editions of the map from the surroundings of Saverne, there is a mention of the vat, between the forrester house of the Schaeferplatz and the top of the Brotschberg (where you can find the tower, the rock and the cave of the Brotsch). You have to follow the way which leads from the Schaeferplatz to the Brotsch during almost 200m, then turn on the right on another little way. This second way rejoins a third one, which leads from the Schaeferplatz to the Hexentisch. The vat is 100m further on this 2nd way.
Neither on the modern edition of the Club Vosgien map (the TOP 25 corresponding to the 3715 OT map from the IGN), nor on the 1988 edition of the 3715 OT IGN map, do the vat and the way which leads to it appear.
I went there recently (July, 4th 1999) and I can assure you that both the way and the vat still exist. The way is marked with a yellow plus sign. You need about 10mn to go from the Schaeferplatz to the vat. The vat itself is a monolithic of sandstone from about 1,80 to 2,00m high and with a diameter of 2,50 to 3,00m. I do not know the age of this vat, nor who made it, nor for which usage. A notice affixed on a tree near the vat gives its altitude: 410m.
On the view above, the surroundings of the stone are empty and you can see the plain in the background. Today, the vat is in the middle of a forest and the firs around it have a diameter of almost 50cm. The way leading to the vat passes along the two little stairs.
If someone has more information about this vat of stone, please let me know.