1. A unit for use in reading a meter, from which meter there may be provided particular electrical connections according to the meter reading, the unit including a plurality of electromechanically operated indicators which are operable serially, one indicator for each digit of the meter reading, conductors for coupling an indictor to the said electrical connections at the meter, means for setting each of the indicators and a rotary switch associated with each of the indicators and means for determining when the setting of an indicator corresponds to a particular connection at the meter; the means for setting each of the indicators including a first switch having first contacts, a transistor associated with each indicator, the first switch being operated via the transistor, a pulse generator, the output of which is connected via a respective first contacts when operated to cause the operation of its associated indicator, an input by means of which a signal may be applied to cause the transistor associated with an indicator to conduct, the corresponding fixed contacts of the rotary switches being connected in common to one of the possible particular electrical connections and the moving contact of each rotary switch being connected via the emitter-base connection of its respective transistor to a conductor associated with a particular digit, whereby a connection may be provided via the moving contact of each rotary switch, the said emitter-base connection of the respective transistor and a corresponding digit reading switch at a meter, whereby when such a connection is made, the transistor is caused to change its state and the first contacts are opened thereby disconnecting the supply of pulses from the generator to the indicator.

7. A unit for use in reading a meter, from which meter there may be provided particular electrical connections according to the meter reading, the unit including a plurality of electromechanically operated indicators which are openable serially, one indicator for each digit of the meter reading, conductors for coupling an indicator to the said electrical connections at the meter, means for setting each of the indicators and a rotary switch associated with each of the indicators and meanS for determining when the setting of an indicator corresponds to a particular connection at the meter; the means for setting each of the indicators including for each indicator a first switch having first contacts, a second switching device, means for operating said first switch operated via connections of the second switching device, an electrical power source the output of which is connected via the first contacts when conducting to cause the operation of the associated indicator, an input by means of which a signal may be applied to cause connections of the second switching device to conduct; the corresponding fixed contacts of the rotary switches being connected in common to one of the possible electrical connections and the moving contact of each rotary switch, connections of said second switching device and a corresponding digit reading switch at a meter, whereby when such path is made said second switching device is caused to change over and the first contacts are opened thereby disconnecting the electrical power source from the indicator.