Simple equations for the lamp performance

The paper is concerned with the finding of new empirical equations for the relations between the “fundamental quantities” of incandescent lamps (voltage, efficiency, candle power, life, wattage, current, and resistance). These equations should be simple and should be free from the main drawback of the equations used heretofore, namely, that the reduction from one given value of a certain “fundamental quantity” other than efficiency, to another value, had to be made in two steps, to and from the “normal” value, the normal value being the value corresponding to a certain assumed “normal” efficiency of the lamp. For instance if we wanted to know at what efficiency a lamp will burn under 110 volts if it shows 1.25 watts per c. under 100 volts, we had to find out first at what voltage the lamp is consuming 1.00 watts per c. A number of new equations is given for the voltage-efficiency and the voltage-candle power relations some of them so simple that they do not require evolution. The accuracy is mostly far better than one half of one per cent. The specific difficulties of the problem and the way of overcoming them are pointed out for application to other relations and other lamps than those for which the equations are given in the earlier portion of the paper.