In railroading, electricity has become an indispensable agent for the operation of signal systems, opening and closing of switches, and limitation of safety sections. It moves the drill in the mine, sets off the blast, and supplies the light. It enables the dentist to manipulate his most delicate tools and do his cleanest and least painful work. In medicine it is a healing, soothing agent, boundless in variety of application and wondrous in results. It is a stimulus to the growth of certain plants, and has given rise to a new science called Electro-horticulture. It may be made a prolific source of heat for warming cars, and even for the welding of iron and steel. The electric fan cools our parlors and offices in summer, and the electric bell simplifies household service. In fact, it would appear that, in contrasting the electrical beginnings with the electrical endings of the nineteenth century, the space of a thousand rather than a hundred years had intervened, and that in measuring the agents which conduce to human comfort and convenience, electricity is easily the most potential. X. ELECTRICAL LANGUAGE. Out of the various discoveries and applications of electricity almost a new language has sprung. This is especially so of terms expressive of the measurements of electric energy, and of the laws governing the application of electric power. For a time, various nations measured and applied by means of terms chosen by themselves. This led to a jargon very confusing to writers and investigators. It became needful to have a language more in common, as in pharmacy, so that all nations could understand one another, could compute alike, and especially impart their meaning to those whose duty it became to apply discovered laws and actual calculations to practical electric operations. This was a difficult undertaking, owing to the tenacity with which nations clung to their own nomenclatures and terminologies. But the drift, though slow, finally ended at the Electrical Congress in Paris in 1881, in the adoption of a uniform system of measurements of electric force, and an agreement upon terms for laws and their application, which all could understand. Three fundamental units of measurement were first agreed upon,—the _Centimetre_ (.394 in.) as a unit of length; the _Gramme_ (15.43 troy grains) as a unit of mass; the _Second_ (1/60 of a minute) as a unit of time. These three units became, when referred to together by their initial letters, the basis of the C. G. S. system of units. Now by these units of measurement something must be measured, as, for instance, the electric force; and when so measured, an absolute unit of force must be the result. DYNE:—This is but a contraction of _dynam_, force. It was adopted as the name of the “Absolute Unit of Force,” or the C. G. S. unit of force, and is that force which, if it act for a second on one gramme of matter, gives to it a velocity of one centimetre per second.