some years the fatality was large because people are always governed by appearances connected with _previous_ notions, until _new_ experiences teach them better.] INSTRUMENTS OF MEASUREMENT.--Some of the most costly and beautiful of modern scientific instruments are those used in the measurements and determinations of electrical science. There are many forms and varieties for every specific purpose. Electrical measurement has become a department of physical science by itself, and a technical, extensive and varied one. Already the electrical specialist, no more an original experimenter or investigator than the average physician is, has become professional. He makes plans, submits facts, estimates cost, and states results with almost certainty. ELECTRICITY AS AN INDUSTRY.--Immense factories are now devoted to the manufacture of electrical goods exclusively. Large establishments in cities are filled with them. The installation of the electric plant in a dwelling house is done in the same way, and as regularly, as the plumbing is. Soon there must be still another enlargement, since the heating of houses through a wire, and the kitchen being equipped with cooking utensils whose heat is for each vessel evolved in its own bottom, is inevitable. The following are some of the facts, in figures, of the business side of electricity in the United States at the present writing. In 1866, about twenty years after the establishment of the telegraph, but with a population of only a little more than half the present, there were 75,686 miles of telegraph wire in use, and 2,520 offices. In 1893 there were 740,000 miles of wire, and more than 20,000 offices. The receipts for the year first named are unknown, but for 1893 they were about $24,000,000. The expenses of the system for the same year were $16,500,000. The telephone, an industry now about sixteen years old, had in 1893, for the Bell alone, over 200,000 miles of wire on poles, and over 90,000 miles of wire under ground. The instruments were in 15,000 buildings. There were 10,000 employés, and 233,000 subscribers. All companies combined had 441,000 miles of wire. Ninety-two millions of dollars were invested in telephone _fixtures_. In 1893, the average cost of a telegram was thirty-one and one six-tenths cents, and the average alleged cost of sending the same to the companies was twenty-two and three-tenths cents, leaving a profit of nine and three-tenths cents on every message. It must be remembered that with mail facilities and cheapness that are unrivalled, the telegraph message is always an extraordinary mode of communication; an emergency. These few figures may serve to give the reader a dim idea of the importance to which the most ordinary and general of the branches of electrical industry have grown in the United States.