_Electrical Musical Instruments_ include pianos, banjos, and violins, all of which are to be played automatically by the aid of electrical appliances. In the illustration, Fig. 74, is shown a modern electrical piano. A small electrical motor 1, run by a storage battery or electric light wires, turns a belt 3, and rotates pulley 4 and a long horizontal cylinder 5 running beneath the keyboard. Above this cylinder is the mechanism that acts upon the keys. It consists of a series of brake shoes which, when brought into frictional contact with the cylinder 5, are made to act on small vertical rods which bring down the keys just as the fingers do in playing. The selection of the proper keys is made by a traveling strip of paper perforated with dots and dashes representing the notes, which strip of paper passes between two metal contact faces, which are terminals of an electric battery. When the contacts are separated by the non-conducting paper the current does not flow, but when the contacts come together through the perforations the current is completed through an electro-magnet, and this is made to bring the proper brake shoe into position to be lifted by the cylinder 5, which rotates constantly. [Illustration: FIG. 74.--ELECTRIC PIANO.] _Electro-blasting._--In 1812 Schilling proposed to blow up mines by the galvanic current. In 1839 Colonel Pasley blew up the wreck of the “Royal George” by electro-blasting. On Jan. 26, 1843, Mr. Cubitt used electro-blasting to destroy Round Down Cliff, and in our own time the extensive excavations in deepening the channel and removing the rocks at Hell Gate, from the mouth of New York harbor, was a notable operation in electro-blasting, and doubtless owes its success largely to the electric current employed. Only the briefest mention can be made of the induction coil and the electrical transformer, of electric bells and hotel annunciators, of electric railway signalling, and electric brakes, of electric clocks and instruments of precision, of heating by electricity, of electrical horticulture, and of the beautiful electric fountains. These, however, all belong to the Nineteenth Century, and include interesting developments. _Electro-chemistry_ and the _electrolytic refining of metals_ represent also, in the applications of electricity, a large and important field, more fully treated under the chapters devoted to chemistry and metal working. CHAPTER X. THE STEAM ENGINE. HERO’S ENGINE, AND OTHER EARLY STEAM ENGINES--WATT’S STEAM ENGINE--THE CUT-OFF--GIFFARD INJECTOR--BOURDON’S STEAM GAUGE--FEED- WATER HEATERS, SMOKE CONSUMERS, ETC.--ROTARY ENGINES--STEAM HAMMER-- STEAM FIRE ENGINE--COMPOUND ENGINES--SCHLICK AND TAYLOR SYSTEMS OF BALANCING MOMENTUM OF MOVING PARTS--STATISTICS.