Grouping of Cells.
Cells may be grouped in a battery to get increased voltage, or increased amperage. When connected for the former, they are in series, the carbon of one is connected to the zinc of the next, and so on.
If all the carbons are connected together and all the zincs, they are in multiple, and will give the same voltage as of one cell but the combined amperage of all.
In ordinary bell work the series is the general connection, the higher the resistance of the circuit, or the longer the wires, the more voltage is required.