be put upon a single sheet economically, the chief point to be effectuated by experiment in this case, being, of course, that each sheet have as great capacity as possible. This form of Phonograph for communications Mr. Edison characterizes as very simple in practice. Thus, a sheet of tin-foil is placed in the phonograph, the clock-work set in motion, and the matter dictated into the mouthpiece, without other effort than when dictating to a stenographer. It is then removed, placed in a suitable form of envelope, and sent though the ordinary channels to the correspondent for whom designed,-he, placing it upon his phonograph, starts his clock-work and listens to what his correspondent has to say; inasmuch, then, as it gives the tone of voice of his correspondent, it is identified, and, as it may be filed away as other letters, and at any subsequent time reproduced, it is a perfect record. A kindred instrument, in some respects, with the preceding, and like that a genuine marvel,-is the MICROPHONE, or transmitter of sound, by the use of which, a mere touch, or so small a sound as the tick of a watch, for instance, may be heard at the distance of miles, and the walking of a fly resembles the tramp of an elephant or the tread of a horse on a rough road. The telephone brings the sound from a distance, and the microphone magnifies the sound when it is thus brought near,thus rendering the latter just as applicable to the sounds transmitted from London or Dublin to New York, if transmissible so far, as to the sounds in a vibrating plate which is within a few inches of the listener's ear. The invention depends on so breaking, by the interposition of charcoal permeated by fine atoms of mercury, the currents transmitted by the telephonic wire, that the sound is vastly increased by the interruption-just as heat is known to be vastly increased by a similar interruption of a current, even to the turning of metallic wire to a red or white heat. the microphone will make a minute sound. audible, whether it be close or far off. Thus cork is fastened to the diaphragm, and presses upon a strip of platinum which is attached to a plate of copper; the latter is one of the terminals of an ordinary galvanic pile. The other terminal plate presses against the metallic frame of the instrument. When the pile is included in a closed telephone circuit, it furnishes a continuous current, the strength of this current depending upon the internal resistance of the pile and its polarization, and these are varied by vibrating the diaphragm; the pile is composed of alternate plates of zinc and copper, and a bibulous medium between the pairs of plates. A simple form of microphone, also, is constructed with a wooden diaphragm oneeighth of an inch thick and four inches square, this being glued to a narrow frame supported by suitable legs. Two pieces of battery carbon are secured by means of sealing wax to the diaphragm, about an inch apart, and at equal distances from the centre. They are both inclined downward at an angle of about thirty degrees. One of the pieces of carbon is longer than the other, and has in its under surface three conical holes, made with a penknife point, which are large enough to receive the upper ends of the graphite pencils, the lower ends of the pencils resting in slight cavities in the lower carbon; these pencils are simply pencil leads sharpened at both ends and placed loosely between the carbons,-they are also inclined at different angles, so that the motion of the diaphragm which would jar one of them would simply move the others so as to transmit the sound properly. The development or conception of the microphone is stated to have been as fortuitous as the discovery of the phonograph. Thus, in the Hughes device, the Professor was led by his experiments to place a small electric battery in circuit with the telephone. He was surprised to find, on adding weights to a fine wire through which the current was flowing, that, just before the breaking strain was reached-just when the fibres of the metal were torn In Edison's pile instrument, a piece of asunder-a peculiar rushing sound was observable in the telephone. He then tried whether he could reproduce this noise by loosely binding the wires again together, and he found that by this means he had hit upon a wonderfully sensitive detector of sounds,-any noise near the wires being immediately taken up by the telephone with startling distinctness. The slightest attachment of the wires procured the same results, and then the joined wires were modified into an apparatus which merely consisted of three nails, two being parallel and connected with the battery wires, and the third resting upon them. Although this ridiculously simple arrangement was capable of transmitting all kinds of noises to a distant place, the sounds were confused. This led to experiments with different conducting substances, the most reliable results, however, being obtained from the various forms of carbon. An arrangement was then devised which not only proved successful, but so sensitive, in fact, as to be almost beyond control, namely, a tiny pencil of fine gas coke dropped into indentations in two blocks of the same material. This compact little instrument, fastened to a cigar box, it was found would transmit to a long distance the ticking of a watch placed near it,— the gentle touch of a feather, or a camel's hair pencil, reached the ear as the rasping of a file, while the scratch of a quill pen in the act of writing was augmented to a loud noise. But better than this form, of course, is that of a base board about three inches long, having screwed upon it two little angle pieces of brass plate, and a metallic bar, pivoted on to these brass supports, with a piece of carbon at its end; this carbon block rests upon two similar pieces kept together by a cloth hinge placed at the side, and the lower block, to which one of the battery wires is attached, is fastened to the board; the pressure upon these carbon surfaces is controlled by a delicate spring of brass wire, which is attached to a screw with a milled head. By turning this screw, the pressure is nicely adjusted, from the very light contact required for delicate sounds to the comparatively heavy pressure wanted when the sounds are more intense. But, to describe this marvelous instrument in the various forms of construction already given to it by inventors at home and abroad, notwithstanding its recent introduction, would require scores of pages. LXXXIII. CENTENNIAL COMMEMORATION OF THE BIRTH OF THE REPUBLIC.-1876. Year of Jubilee, Festival, and Pageant, throughout the Land.-Prosperity, Power, and Renown of the Nation. A Union of Nearly Forty Great Commonwealths and Forty Million People.-Anticipations of the Coming Anniversary.-Legislation by Congress for its Patriotic Observance.-A Grand Exposition of the Century's Growth and Progress, the Principal Feature Decided Upon-Vast Work of Preparation.-The Whole World at Peace, and All Countries and Climes in Sympathy with the Republic and its Auspicious Era.-Ushering in the Year's Ceremonials.-Every City, Town, and Village, Covered with Gay Streamers and Waving Flags.-Pomp, Parade, and Universal Fraternization.-Wondrous Microcosm of Civilization Concentrated at Philadelphia.-The Culminating Art and Skill of Sixty Centuries of Human Advancement, and the Products of Every Quarter of the Globe, Displayed in their Richest Illustrations.-An Unprecedented Scene: President and Emperor Receiving the Salutations of the American People.-Oratory, Music, Poetry, Bells, Illuminations, Cannon, Regattas, Banners, Hallelujahs and Huzzas.-The Beauty, Utility, and Magnificence of the Orient and Occident, in Boundless Combinations.-The "Glorious Fourth," All Over the Land. -Congratulatory Letter from the Emperor of Germany. "The completion of the first century of our national existence should be commemorated by an Exhibition of the natural resources of the country and their development, and of its progress in those arts which benefit mankind."-PRESIDENT GRANT'S MESSAGE TO CONGRESS. nearly forty great commonwealths and forty million inhabitants, and, in respect to whatever relates to man's material and moral advancement, found themselves unexcelled by any empire or kingdom on the face of the wide earth. Anticipations of the coming anniversary had long been prominent in the minds of the people, and, in view of the peculiarly national character of the event, it was at an early stage of the discussion brought before the assembled wisdom of the republic, in the halls of congress, the result of which was the adoption of the idea that had for some time become widely popular, namely, that an exhibition of American and foreign arts, products, and manufactures be held, under the auspices of the government of the United States, in the city of Philadelphia, in the year 1876. To this end, the centennial commission was appointed-two commissioners from each state and territory, nominated by their respective governors, and approved by the president. Under this organization, the vast work of preparation commenced, and, on the fourth of July, 1873, the ground set apart for the purpose was dedicated with appropriate ceremonies. The result of the succeeding three years of labor on the part of the commission, showed that not only from every section of our own land did the choicest contributions accumulate in every department of art, science, and mechanism, but that all foreign countries also,-in response to the invitation extended to them by the American government, were in sympathy with the Republic and its auspicious era; so that, at the time designated for the grand ushering in of the year's ceremonials, there was presented the most wondrous microcosm of civilization ever concentrated in one locality. There was, in fact, the culminating art and skill of sixty centuries of human advancement, and the products of every quarter of the globe, displayed in their richest illustrations, the beauty, utility, and magnificence, of the Orient and Occident, in boundless combinations. On the day of the formal inauguration of the exposition, and at which were present hundreds of thousands of joyous spectators, with dignitaries from both hemispheres, the occasion was appropriately introduced by the vast orchestra performing the national airs of all nations, as fol lows: The Washington March; Argentine Republic, Marche de la Republica; Austria, Gott erhalte Franz den Kaiser; Belgium, La Brabansonne; Brazil, Hymno Brasileira Nacional; Denmark, Volkslied den tappre Landsoldat; France, La Marseillaise; Germany, Was ist des Deutschen Vaterland; Great Britain, God Save the Queen; Italy, Marcia del Re; Netherlands, Wie neerlandsch bloed; Norway, National Hymn; Russia, National Hymn; Spain, Riego's Spanish National Hymn; Sweden, Volksongen-Bevare Gud var Kung; Switzerland, Heil dir Helvetia; Turkey, March; Hail Columbia. Following this musical prelude, the bold chords of Wagner's centennial inauguration march filled the air with floods of richest harmony; solemn prayer was offered by Bishop Simpson; and then a superb chorus of nearly a thousand voices, accompanied by orchestra and organ, sang Whittier's centennial hymn, set to music by John K. Payne. Formal presentation being now made of the building to the United States Centennial Commission by the president of the board of finance to General Hawley, president of the centennial commission, a cantata was sung with fine effect, the words by Lanier, of Georgia, and the music by Buck, after which the ceremonial presentation of the Exhibition to the President of the United States was made by General Hawley, in an eloquent address, to which General Grant responded in a eulogistic speech of acceptance, reviewing the progress of the century, bidding the whole world welcome, and declaring the exhibition open. On this announcement, the orchestra, chorus and great organ burst forth into triumphal strains of the Hallelujah,' from the "Messiah," acclamations and huzzas rent the air; and the unprecedented spectacle was witnessed, of an American President and a crowned Emperor-the emperor of Brazil being present, and at President Grant's side,-receiving the enthusiastic salutations of the American people. The case of Dom Pedro, it may be here remarked, furnishes the only instance in |