This difficulty M. Gramme overcame with characteristic ingenuity by adding to the ordinary system a "distributer" capable of delivering plus and minus currents alternately, thus equalizing the consumption, besides being able to supply a large number of candles on the multiple circuit system, each circuit supporting four or five lamps. Thus it will be seen that a result was attained which at least gave such men as Siemens, Gramme, and their peers, if such there be, confidence in the future and a courage which quickly placed the new science safely beyond the limits of the laboratory. I will not occupy your time by stating the apparent reasons why the Jablochkoff candle has not fully sustained its brilliant promise--it will, perhaps, be sufficient to state that it is now superseded practically, though it must always occupy an honorable place in scientific annals. Let us now for a few moments consider what the electric light really accomplished at about this period, I mean from an economical standpoint. It appears from some data furnished by an engineer commissioned by the French Government that the machines were then capable of maintaining a light equal to from 220 to 450 candles, measured by comparison with the Carcel burner, per horse power absorbed--a very good showing considering the youth of the discovery, but presenting rather a gloomy aspect when we consider that according to Joule's mechanical equivalent of heat, which is 772 foot pounds, or the power required to raise one pound of water one degree--and for lack of anything better, we are obliged to accept that at this moment--the whole force contained in one pound of coal would maintain a light equal to 13,000 candles for one hour! That is the ultimate force, and what we are now able to accomplish is but a small fraction of this amount. Unfortunately we are but common mortals, and cannot, like Mr. Keely, lightly throw off the trammels of natural law; we must, therefore, endeavor to close this gap by patient study and experiment.