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The Campbell Frequency Meter is described. After a short statement of the new system, its various advantages are pointed out, e.g. the reading by single adjustment, the very long smooth-running range, or numerous very open short range, the high accuracy and sensitivity, and the practically negligible temperature coefficient.

The main objections to the usual type of thermostat for controlling high temperatures are that it cannot be used for a long time at temperatures over 1000° C., it cannot be applied directly to the control of every type of resistance furnace, the part actually in the furnace is fairly large, and the external apparatus cannot readily be placed at any great distance from the furnace. In this note a description is given of a thermostat which overcomes these objections.