A Brahman priest recites morning prayers (puja) to mother Ganga.
In the left frame of the diptych, the Brahman uses a snake shaped fire holder and makes repeated circular motions toward the river Ganges. In the right frame, he's seen throwing garlands into the air. Ask me the significance of any of this and I can tell you a lie to pretend I know. Ask any Indian the significance of any of this and they will tell you a lie to pretend they know. It seems no Indian I asked seems to know but certainly they want to pretend to know. Out of several different people I questioned, I received several distinct answers. So at the end of the day, it's just easier to say the Brahman is reciting prayers.