THE Board of Trade electrical unit is the kilowatt-hour, which signifies a consumption of energy at the rate of 1,000 watts in an hour, or at a smaller rate for a corresponding longer time. The companys meter registers the units as they are consumed, and the householder pays accordingly. A 40-watt lamp will run = … Read more


THE gas-filled lamp has now largely superseded the vacuum lamp, as it emits a whiter light and is more efficient: that is, gives more light proportionately to the electrical energy used. The bulb, after being exhausted of air during manufacture, is filled to half atmospheric pressure with a gas called argon, which is unable to … Read more