The paper reviews briefly some existing methods of load-angle measurement, and describes two alternative arrangements in which the measuring circuit proper is controlled by a simple commutator coupled to the shaft of the machine under test. The load angle under steady-state conditions is indicated direct on a calibrated instrument of standard pattern (e. g. a centre-zero milliammeter, or a current-ratio indicating instrument), while an oscillogram of current in the measuring circuit provides a continuous record, cycle by cycle, of load-angle fluctuations under transient conditions. In either case, the one unit can be adapted for use with any machine, irrespective of its number of poles, by appropriate rearrangement of the connections to the commutator segments, and the sensitivity can be adjusted to cover any required range of load-angle variation.