Mazda lamps are the most efficient lamps obtainable and their use is recommended for all classes of service. Your electric bills depend upon the watts per lamp and the number of hours of use. Note in the following table that the Mazda lamps give on the average two and one-half times as much light for the same cost as the Gem carbon lamps. The column “Cost of current per month” gives the cost of burning one lamp one hour per day for one month at the maximum rate of nine cents per K. W. H.