While doing an experiment with a potentiometer (figure), it was found that the deflection is one-sided and (i) the deflection decreased while moving from one end A of the wire to the end B; (ii) the deflection increased, while the jockey was moved towards the end B.

                      

(i) Which terminal, positive or negative of the cell E1, is connected at X in case (i) and how is E1 related to E?

(ii) Which terminal of the cell E1, is connected at X in case (ii)?

Hint: The potential drop across the end A and the jockey depends on the current in the wire AB.
Step 1:
(i) The deflection in the galvanometer is one-sided and the deflection decreased while moving from one end 'A' of the wire to the end 'B, this implies that current in the auxiliary circuit (lower circuit containing primary cell) decreases, while potential difference across A and jockey increases.
This is possible only when the positive terminal of the cell E1 is connected at X and E1 > E.
Step 2:
(ii) The deflection in the galvanometer is one-sided and the deflection increased, while moving from one end A of the wire to end B, this implies that the current in the auxiliary circuit (lower circuit containing primary cell) increases, while potential difference across A and jockey increases.
This is possible only when the negative terminal of the cell E1, is connected at X.