Abstract
1. The word life of electric incandescent lamps of a certain kind or of a certain specified set, means the average life of all the lamps belonging to the kind or to the set in concern, though the life of an individual lamp may deviate somewhat from the average as the human life varies within a certain range.The frequency distribution of life (Fig.2) of a number of lamps may be considerd as it is almost definite if we take sufficiently large number of lamps in analogy of that of human life (Fig.1) which is almost definite year by year, so the average of all of the lamps may also be considered as almost constant, or more definite than human life since the frequency distribution curve of lamps is more regular than that of human life.
2. The life of lamps is the time of actual burning while the human life is the time from birth to death.
3. The word life was used in several meanings expressing various ideas concerning to life in succcssive periods.
