Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. These considerations show very clearly the main facts at issue in the case of transmuting the potential energy of zinc into current electricity, and thence into mechanical effect. They show conclusively that it is hopeless to expect that electro-motors, the power of which was derived from zinc, could compete with steam engines, and they thus exhibit at a glance the main cause of failure in the earlier types of the electro-motive machine. Nevertheless, the great convenience attending the use of small moving powers, conveyed through thin flexible conductors, may in many instances counterbalance the cost of working, and render miniature electro-motive apparatus, actuated by currents derived from the consumption of zinc, extremely useful. Moreover, the efficiency of the older forms of electro-motor was very small. It is doubtful whether a return greater than 30 per cent. As mechanical force was available. The investigation of the mechanical equivalent of heat brought to light other facts than those which led to the conclusion that zinc motors must be fifty times as expensive in working as coal' motors. It showed that every form of energy was convertible into every other form. Thus, since it is evident that we can never create energy of any kind, we must confine ourselves to converting one form into another form. In the case of electric energy being transformed into mechanical effect.

These considerations show very clearly the main facts at issue in the case of transmuting the potential energy of zinc into current electricity, and thence into mechanical effect. They show conclusively that it is hopeless to expect that electro-motors, the power of which was derived from zinc, could compete with steam engines, and they thus exhibit at a glance the main cause of failure in the earlier types of the electro-motive machine. Nevertheless, the great convenience attending the use of small moving powers, conveyed through thin flexible conductors, may in many instances counterbalance the cost of working, and render miniature electro-motive apparatus, actuated by currents derived from the consumption of zinc, extremely useful. Moreover, the efficiency of the older forms of electro-motor was very small. It is doubtful whether a return greater than 30 per cent. As mechanical force was available. The investigation of the mechanical equivalent of heat brought to light other facts than those which led to the conclusion that zinc motors must be fifty times as expensive in working as coal' motors. It showed that every form of energy was convertible into every other form. Thus, since it is evident that we can never create energy of any kind, we must confine ourselves to converting one form into another form. In the case of electric energy being transformed into mechanical effect.