The important paper on “The Application of Electric Heating to Domestic Hot-water Supply Systems” read to the Institution of Electrical Engineers and to seven local centres is published in the Journal of the Institution of July. In the discussion, Mr. A. E. McKenzie, engineer to the Wimbledon Corporation, said that in the three towns supplied by his undertaking, there are 38,000 consumers taking electricity and 17,633 electric water heaters. This gives one water heater for every 2·15 houses, or approximately 46 per cent saturation. In addition, there. are a large number of publicly owned heaters. In Wimbledon, all self-contained water heaters are cleaned out once in two years, and four improvers are employed continuously on this work. All the heaters in a street are cleaned at the same time, thereby cutting maintenance costs down to a minimum. Taken over a period of years, the cost of cleaning such heaters, both large and small, averages 1 d. per month. As the numbers increase, it is hoped that this cost will soon fall. The problem of ‘scaling’ is more serious with the small heaters than with the big ones. Most of the scale is deposited at the top of the outlet pipe and at the anti-dripping device which is immediately over it. There is no necessity to remove any of the electrical connexions. This enables the heater to be renovated in less than half the time and at less than half the cost formerly necessary. A strong case can be made out for the claim that the electric water heater is more trustworthy than any other type. At Wimbledon there are 5,000 of the self-cleaning typo installed and there has not been a failure. Serious accidents due to electric water heaters are practically unknown. During the severe weather last winter, only twelve heaters were put out of action, all of which functioned immediately the ice was melted in the supply pipes.