4-row Concentric (PY cane)

A high-domed 4-row concentric centred by a large, white cane underlaid with translucent green. Surrounding the centre are blue/white florets and alternating colourful complex canes, with a PY signature cane set between them. In the 3rd row, complex canes alternate with pairs of green/white cogs while the outer row has alternating blue & amber canes.
The base is unusual for Ysart ... a wide polished, flat rim with a central concavity. The strong purplish tint to the melt would indicate an early weight - probably pre-1940.