Transformation of electric power into light

Of all the achievements of modern science or engineering the production of light is the least creditable. In the transformation of electric power into mechanical power, as in the electric motor, or the transformation of mechanical power into electric power, as in the dynamo, efficiencies far higher than 90 per cent. have been reached. The transformation is practically complete. All further advance must be expected in the direction of increased reliability of operation, decreased size and cost, etc. Even in the steam-engine or steam-turbine, 60 per cent. or more of the available energy of the steam as it issues from the boiler is recovered as mechanical work.