4" X 4 1/4" (98mm X 104mm)

(top embossed) BULLER JOBSON & CO LIMITED (in circle)

K / DUDLEY / 180 (in center)  

{Bullers}

Picture courtesy Elton Gish

4" X 4 1/2" (100mm X 115mm)

(top embossed) SIEMENS PATENT 1 

Picture courtesy George Sukhoff

4" X 4 1/2" (100mm X 115mm)

(top embossed) SIEMENS PATENT 1  

Picture courtesy George Sukhoff