Chapter L: J. M. Daguerre, born 1787, died 1851 (4)

A special feature of recording instruments may be exemplified by certain applications of the principle to the investigation of physiological actions. A skilled physician is often able to detect in the pulse of his patient certain characteristics besides the mere rate, which are highly significant as regards the condition of the circulatory system. The range of these indications has been greatly extended by an instrument invented by MM. Chauveau and Marey, by which the pulse is made to write down a graphic representation of its action. The patient’s arm having been placed on a suitable support, a little stud covered with soft leather is lightly pressed against the artery by a spring. The stud is in contact with the shorter end of a very light lever, the other extremity of which is furnished with a point, which registers its movements on a cylinder of blackened metal, made to rotate and advance longitudinally by clockwork; or the record is taken on strips of flat smoked glass. As the motion is much magnified by the lever, every variation in the pressure of the blood in the artery during the beat of the pulse is distinctly and faithfully indicated. From the line so traced the physician may obtain infallible data for judging of the condition of the heart, the action of its valves, &c. It is marvellous to observe the manner in which the curves of the _sphygmograph_, as the instrument is termed, change their form when certain drugs are administered: the change in some cases occurs immediately, so that the eye can detect by the inspection of the sphygmographic curve almost the instant at which the drug was introduced into the system, and the nature of its action on the heart.

FIG. 317.—_Negretti’s Deep-Sea Thermometer._
]

Another instrument which is doing good service in the hands of medical investigators is the _spirograph_, in which the rise and fall of the chest in breathing are similarly traced by the motions of a lever. In this instrument a small pad, which presses on the chest, communicates its movements to an elastic membrane, which, like the skin of a drumhead, covers one end of a cylindrical box maintained in a fixed position relatively to the person of the patient. The air in this box is in communication, by means of a flexible tube, with the interior of another similarly closed box; the elastic membrane of the latter acts against the short end of a lever, which is made to register its movements as in the sphygmograph, for the compression of the air caused by the rise of the chest is conveyed to the second box through the flexible tube. The curves furnished by this instrument also give valuable indications, and exhibit marked changes under any influence in the least degree affecting the respiratory system.

The value of a self-registering instrument for solving problems, the intricacy of which is increased by the multiplicity and rapidity of the actions to be observed, cannot be better illustrated than by the success with which Professor Marey has thus studied some complicated actions of locomotion, as related in his extremely interesting work entitled, “La Machine Animale,” a translation of which has appeared in “The International Series.” The action of the horse in the various paces, walking, trotting, galloping, &c., has been an endless subject of discussion, with no other data than the shoe-marks left in soft ground, and the general appearance of the animal’s movements to an observer. But M. Marey—by means of elastic bags containing air, communicating the pressure through flexible tubes, so as to move little levers, which write their traces on a revolving cylinder impelled by clockwork, and carried by the rider,—has completely and finally settled all the points in dispute. It is now definitely known how the horse’s feet are placed on the ground in each of his paces, and the actual and relative time that each foot remains down. The instruments are also made to register the vertical movements of the animal, so that a complete record of its motion can be obtained.

FIG. 318.—_Negretti’s Deep-Sea Thermometer, general arrangement._
]

It was long a difficulty to obtain data as to the temperature of the sea at great depths below the surface. It is obvious that the ordinary maximum and minimum registering thermometers would not give the temperature at any particular depth to which they might be submerged, but merely the temperature of the warmest or coldest stratum of water through which they passed in their descent or ascent. No plan which has been devised to obviate these difficulties appears to have been attended with success, until a quite recent invention of Messrs. Negretti and Zambra supplied the desideratum, and furnished a convenient instrument for trustworthy determination of the temperature of the ocean at any required depth. The same firm long ago constructed thermometers for deep-sea soundings, with bulbs protected from the pressure of the water by an outer covering of thick glass surrounding the delicate bulb of the thermometer, between which and the outer casing a space was left, partially filled with mercury, so that heat might readily pass to or from the inner bulb without the latter being exposed to the superincumbent pressure. The new recording deep-sea thermometer differs, however, from all other registering thermometers by containing mercury only, without alcohol, or springs, or other removable indices, and, consequently, it is free from liability to derangement. The following is the description of the instrument:

In the first place it must be observed that the bulb of the thermometer is protected so as to resist the pressure of the ocean, which varies according to depth, that of 3,000 fathoms being something like 3 tons pressure on the square inch. The new instrument is in shape like a syphon with parallel legs, all in one piece, and having a continuous communication, as shown in Fig. 317. The scale of the thermometer is pivoted on a centre, and being attached in a vertical position to a simple apparatus (which will be presently described), is lowered to any depth that may be desired. In its descent the thermometer acts as an ordinary instrument, the mercury rising or falling according to the temperature of the stratum through which it passes; but so soon as the descent ceases, and a reverse motion is given to the line, so as to pull the thermometer towards the surface, the instrument turns once on its centre, first bulb uppermost, and afterwards bulb downwards. This causes the mercury, which was in the left-hand column, first to pass into the dilated syphon-bend at the top, and thence into the right-hand tube, where it remains, indicating on a graduated scale the exact temperature at the time the thermometer was turned over. The cut shows the position of the mercury _after_ the instrument has been turned on its centre. A is the bulb; B the outer coating or protecting cylinder; C is the space of rarefied air, which is reduced if the outer casing be compressed; D is a small glass plug, as in Negretti and Zambra’s maximum thermometer, which at the moment of turning cuts off the mercury in the tube from that in the bulb, thereby ensuring that none but the former can be transferred into the indicating column; E is an enlargement made in the bend, so as to enable the mercury to pass quickly from one tube to another in revolving; and F is the indicating tube, or thermometer proper. When the thermometer is put in motion, as soon as the tube has acquired a slightly oblique position, the mercury breaks off at the point D, runs into the curved and enlarged portion, E, and eventually falls into the tube, F, as the instrument resumes its original vertical position.

FIG. 319.—_The Atmospheric Recording Instrument._
]

The contrivance for turning the thermometer over at the bottom of the sea may be described as a vertical propeller, to which the instrument is pivoted. So long as the instrument is descending the propeller is lifted out of gear and revolves free; but as soon as the ascent commences, the action is reversed, the propeller falls into gear with a pinion connected with the thermometer, and by these means the thermometer is turned over, and after one turn it remains locked and immovable. The engraving, Fig. 318, shows the general arrangement, T being the thermometer, S a metal screw connected with the frame of the thermometer by a wheel-and-pinion movement at W; S^† is the stop for arresting the movement of the thermometer when it has made one complete turn.

The atmospheric recording thermometer (Fig. 319) differs from the deep-sea thermometer by not having the double or protected bulb, as it is not required to resist pressures. In this form of the instrument, the thermometer is turned over by a simple clock movement, which can be set to any hour that may be desired. It is fixed on the clock, and when the hand arrives at the hour determined upon, and to which the clock has been set as an alarum clock is set, a spring is released, and the thermometer turns over as before described. A wet and dry-bulb hygrometer is also arranged on the same plan. For observatories, or where it is important to obtain hourly or half-hourly records of the temperature, twelve or more thermometers are placed on a frame, and these are turned over by clockwork one after the other at every hour or half-hour as required.

The reader can hardly fail to perceive that powerful aid to the investigation of the laws of nature must be afforded by such instruments as we have described. And we have but taken an example here and there of the scientific uses of the recording principle, selecting those that are most readily understood, or that are connected with matters coming home to the business and bosom of every one. The science of meteorology does not deal with subjects which furnish merely amusing speculation for the hour. Forecasts of storms and cyclones would often save many lives and much valuable property; and our dependence upon meteorological conditions cannot be more forcibly illustrated than by reference to the disastrous floods which this year (1875) desolated some districts of France. Meteorology has received a great impulse from the introduction of recording instruments; and the vast number of results which are now hourly recorded must lead to the certain development of the science, and its reduction to exact laws. For even the winds obey laws—laws as definite as those which control the motions of the planets; and could we but take into account _the whole_ of the circumstances upon which the movements and other conditions of the atmosphere depend, we should be able to forecast the weather with the same certainty as—thanks to the great and simple law of gravitation—we predict eclipses or other astronomical phenomena. Already, by aid of the telegraph, it is often possible to send a day’s warning of approaching storms to localities lying in their probable track. The Signal Service, which is a Department of the United States War Office, has a corps of meteorological observers spread over the length and breadth of the States, who send every eight hours, to a Central Office in Washington, a report of the force and direction of the wind, height of the barometer, &c. The officer at Washington sends back by telegraph to the public press a synopsis of each day’s weather, and points out what weather will probably follow; but if any city or port be threatened with a storm, special telegrams are sent. Thus, a warning of the approach of a great storm, which entered the American continent at San Francisco on the 22nd Feb., 1871, was sent to Cheyenne, Omaha, and Chicago, twenty-four hours before the storm reached these cities, which it was foreseen lay in its track. Although the hurricane did much damage at some of these places, it would probably have been far more destructive had not the inhabitants been prepared for its approach.

An elegant form of _barograph_ or recording barometer has been brought out, which is small, but sufficiently accurate for all ordinary purposes. It is founded on the _aneroid_, which, as everybody knows, is an instrument for indicating atmospheric pressure by the changes of form it produces in a thin circular metallic box, partially exhausted of air. The ordinary form of the aneroid is very sensitive and portable (sometimes it is made only the size of a small watch), and bears an index needle moving over a graduated disc; which arrangement is in the barograph aneroid, replaced by a long lever, carrying an ink tracing point in contact with the face of a cylinder that is caused by clockwork to make one revolution per week. On the cylinder is spread a printed paper diagram, divided by lines for each day of the week and each hour of the day, and on this the tracing point marks a continuous curve, showing all the fluctuations of the barometric pressure. The diagram is removed at the end of the week, and a fresh form adjusted to the cylinder. The impressed papers thus form a permanent and continuous record, from which the height of the barometer, at any given moment, may be read off.

_THE PHONOGRAPH._

Everything yet contrived in the way of recording instruments is eclipsed in wonder and interest by one which is among the latest marvels of the age. It is a recording instrument, and more than a recording instrument, for it can reproduce to the senses the very phenomena it records; and these same phenomena are the most familiar in their effects, and, at the same time, so subtle and delicate, that the impressions they convey are not generally thought of otherwise than in connection with our finest intellectual and emotional perceptions. We are alluding to the _phonograph_, which can register for us music and song, and articulate human speech in all their tones and modulations, and, like an aërial spirit, address them to the ear again, as often as we wish, and thus

Inform the cell of hearing, dark and blind;
Intricate labyrinth, more dread for thought
To enter than oracular cave,
Strict passage through which sighs are brought,
And whispers for the heart, their slave;
And shrieks, that revel in abuse
Of shivering flesh; and warbled air,
Whose piercing sweetness can unloose
The chains of frenzy, or entice a smile
Into the ambush of despair;
Hosannas pealing down the long-drawn aisle,
And requiems answered by the pulse that beats
Devoutly, in life’s last retreats!

In order that the reader may understand the action of the phonograph, it is necessary that he should know something of the science of sound. Then we must remember that this word is commonly used to express sometimes those sensations of which the ear is the organ, and at other times the external cause of those sensations. It is with the former meaning that we use such expressions as “a sweet sound”; with the latter, such phrases as “sound travels.” It will not be necessary to speak of the physiology of the organ of hearing; but attention should be directed to the different kinds of audible perceptions we can distinguish, let us suppose, when listening to a song: First, there is the pitch, or the notes in the musical scale, which, by their particular sequence, constitute the air or melody. Second, there is the degree of loudness or lowness of the notes. Third, the enunciation, or those differences by which we distinguish, for example, the vowels _a_, _e_, _i_, _o_, _u_, one from another. Fourth, the quality of the voice by which we can distinguish between two vocalists singing the same vowel on the same note with equal loudness. Observe that these four kinds of sound perceptions are independent one of another. The last kind of difference may also be well illustrated by the instance of musical instruments of different kinds sounding the same note, in which case the difference of the quality or _timbre_ is readily recognized. We have now to show the nature of the mechanical movements outside of us which act on the ear and reach our perception as sounds, giving the distinguishable impressions that have been enumerated; and for the present we shall consider the case of such musical sounds as those just referred to.

That the source of a sustained sound is an elastic body in a state of vibration is a fact of which, in most cases, we are easily made aware by the evidence of sight and touch; as a bell, a violoncello string, a pianoforte wire, or a tuning-fork. On p. 656 is described a simple method by which a tuning-fork may be made to write down its own vibrations, and the more exact plan of recording them on the surface of blackened paper on a revolving and advancing cylinder has also been referred to. By the intervention of appropriate apparatus, a similar record may be obtained from all sounding bodies. From observations of this kind, and others in which totally different methods are used for counting the number of vibrations per vibrations made in a given time, it is known that the _pitch_ of the sound or note depends on the rapidity of the vibrations—the pitch rises with the number of them per second, and the relationship between the notes of a musical scale depends entirely on these numbers. Thus, when the vibrations for the eight notes of an octave are counted, the numbers always have this _proportion_, beginning from the lowest note-–24, 27, 30, 32, 36, 40, 45, 48. Thus of the two notes—

[Music]

as produced on musical instruments tuned to the concert pitch of the present day, the lower corresponds with 264 complete vibrations per second, the higher with 528. It will be observed, too, that all the harmonies are determined by some simple ratio in the rates of vibration: the interval of the _fourth_ is 3, 4; that of the _fifth_ is 2, 3, etc. Another easily discoverable fact is that the loudness of the sound depends upon the amplitude of the vibrations. This is sufficiently obvious by a few experiments with a tuning fork; and by close examination of such tracings as have been mentioned, we shall soon become aware of another circumstance—namely, that the vibrations not simple, but that the larger or general movement has one or more sets of small vibrations within it. In Fig. 319_a_, A is the curve that would be traced by the tuning-fork in a state of simple vibration; B and C are tracing such as are given by a fork in two of its modes of vibration. The fork gives out its proper or fundamental note in both cases; but the ear recognizes a difference in the quality of the sound due to the smaller and more numerous vibrations. Differences of the same kind are recognized in the notes produced by different musical instruments; but these are usually more complicated, and their forms are characteristic of the particular quality of the tone, which is thus shown to be due to the superposing of several related systems of vibration upon the fundamental one. Thus three out of the four qualities of sound recognized by the ear have had their physical causes assigned. As for the fourth—namely, the distinction we perceive among the different vowels sung on the same note—it has a physical origin identical with the last. For since parts of the vocal organs assume different positions in enunciating the different vowels, they constitute for the time being so many varied musical instruments, and the graphical traces of the sounds (for they can be obtained) show a corresponding modification. Here, in Fig. 319_b_, for example, are represented the tracings of the vibrations given to the air in various vowel sounds. It is also through the vibrations conveyed by the air to the little membrane called the drum of the ear that the sensations of sound are received, and of the nature of these vibrations a few words must be said presently. In considering the different qualities of sound, we have so far confined ourselves to sustained musical notes, as, for instance, the vowel sounds in singing. This has been done to show the relations of rapidity of vibration to pitch and for simplicity of illustration of the superposition of vibrations, etc. Two other remarks must be added—viz., that the vibrations of musical tones are _isochronous_—that is, whether the note be loud or soft, the same time is taken up in each vibration corresponding with the same fundamental note. Other vocal sounds than sustained vowel notes are found to be due to still more complicated combinations of vibrations of shorter duration, and _noises_, as distinguished from musical sound, are formed also by the superposition of a greater or less number of systems of vibrations, the rapidities of which are wanting in harmonic relations such as we have pointed out belong to the musical scale. Even in noises, however, there is often one or more predominant systems of vibrations which a musical ear can detect. If the reader will hold a pencil or penholder at one end and tap with it on the edge of the table, passing in quick succession to parts progressively nearer where the pencil is held, he will hardly fail to recognize a rising pitch in the little noises.

FIG. 319_a_.—_Traces of Vibrations of a Tuning-Fork._
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FIG. 319_b_.—_Phonautographic Tracings of Different Vowel Sounds._
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FIG. 319_c_.—_Diagram._
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FIG. 319_d_.—_Phases of Sound Waves._
]

A word or two must be said as to the way in which sound is transmitted through the air. This progression is commonly spoken of as a wave motion, but it must not be thought of as taking place in the form familiar to us as waves on water; still less must the reader confound it with the sinuous lines shown in the graphical representations of vibrations given in the figures. It is rather a series of rapid pulsations of the particles of the air taking place in the direction in which the sound is propagated, and resembling waves on water only by presenting periodical phases in uniform succession. The difference may be illustrated from what may be seen in a field of wheat when the wind is blowing over it. The stalks bend down, and rise again when the breeze has passed, and thus the general appearance of the waves of the sea is produced. If we confine our attention, however, to the motion of the several ears of the wheat in a file of stalks, we shall obtain a clearer notion of what takes place in the so-called waves of sound. The positions of the stalks at some one instant of time may be represented by the diagram, Fig. 319_c_. Each stalk is swinging backwards and forwards like an inverted pendulum, and the successive phases of these vibrations bring the adjacent ears nearest to each other about _i_, and farthest apart at _a_ and _a´_. The places of these, and of all the intermediate degrees of approximation and retreat, pass along the file. Instead of the ears of wheat swinging on their elastic stalks, suppose particles of air approaching and receding by virtue of the elasticity by which they resist compression and recover from it, and you will obtain an elementary idea of what takes place in the transmission of sound. Fig. 319_d_ is a picture of a column of air acted upon by a tuning-fork. The swiftly advancing prong is compressing the air in front of it, and in swinging back it will tend to leave a vacuum behind it by which the air is partially rarefied; and these alternate condensations and rarefactions will travel along through the air by virtue of its elasticity, and the mechanical action by which they are able to agitate a stretched membrane (or other elastic body), so that its vibrations will correspond with them in period and magnitude, may be easily understood. The vibration produced is a simple one, but any number of other systems may pass at the same time, and each one will be propagated as if the rest did not exist, just as we may see different systems of undulations moving on the surface of water. It should be observed that the velocity of propagation is the same whatever may be the period or the magnitude of the vibrations. The high and the low, the loud and the soft notes of a piece of music played at a distance, all take the same time in reaching the ear. Light as are the particles of air, the mechanical actions which a number of them carrying strong vibratory impulses will produce, may be illustrated by the rattling of window panes by a loud peal of thunder, and may be bodily felt by a person standing close to a very large bell while the hour is striking.

We have referred to instruments for registering sound, and even vocal sounds, before anything has been said of the construction of the phonograph, and it is, in fact, many years since the problem was solved of recording the vibrations produced by speech. Mr. Leo Scott, in 1856, invented an instrument, called the _Phonautograph_, which did this. It consisted of a cone of sheet zinc like a large ear-trumpet, across the smaller end of which was stretched a membrane, having attached to it a very light style, which left a record of the vibrations of the membrane on a blackened cylinder properly disposed to receive the tracing. When any sound was produced near the open end of the cone, the impulses reflected from its internal surface were concentrated on the membrane, throwing it into corresponding vibrations. Now, this process could be reversed if the tracing could be made to give back again to the style its original movements, these transferred to the membrane would throw the air within the cone into corresponding vibrations, and the sounds that gave rise to the tracing would be reproduced. Yet Mr. Scott seems to have suggested no such possibilities for his instrument; but a few years after the invention of the phonautograph, M. Cros deposited at the Academy of Sciences in Paris a sealed paper, which was opened after Mr. Edison had patented the phonograph (1877), and found to contain suggestions of how this might be done, but describing no experiments in which any approach had been made towards realizing the conditions laid down. To Mr. Edison belongs the honour of solving the problem by the invention of the phonograph, which was patented by him in 1877. The device which he happily hit upon for converting the phonautograph into a phonograph was very simple in principle, and consisting merely in substituting a sheet of tinfoil for the blackened paper in Scott’s apparatus, the mechanism required for reproducing articulate human speech was thus found, contrary to all expectations that had previously been entertained, to be essentially of a remarkably simple character, for the arrangement of the parts was even more direct than in the phonautograph itself. This is not derogatory to the merit of the inventor, for every invention depends upon something previously attained, and the discovery of suitable materials for the various parts of the machine, and the many delicate adjustments of their forms and disposition to secure the required object, demanded the application of very remarkable experimental skill. The phonograph differs from the phonautograph by giving up what it has registered in the original form and material, and thus it is a speaking machine. It is a speaking machine which _reproduces_ articulate speech, not produces it. Much ingenuity has been devoted to the construction of speaking machines which should be capable of _producing_ the sounds of the human voice. By throwing into vibration the air contained in cavities of certain shapes, it was long ago found possible to produce sounds closely resembling those of a voice singing particular vowels, and a real speaking machine that could articulate words was exhibited in America before the phonograph had been brought out. It was constructed by Mr. Faber, and formed a very complicated arrangement, in which all the organs of human speech were imitated. There were bellows acting like the lungs; a larynx with various diaphragms, a mouth with movable tongue and lips, and a tube to resemble the cavity of the nose. The positions and connections of these parts were determined by levers acted from a key-board, like that of a piano, and by certain pedals. By moving these in proper order, the machine pronounced words distinctly enough, but in a strange drawling tone. So like, however, were the sounds to those of the human voice, that some accused the exhibitors of imposition, and unjustly credited ventriloquism instead of mechanism with the results. It will be observed that it is the function of the phonograph to reproduce, not produce, human speech, and the mechanical arrangements of the instrument are simplicity itself compared with Faber’s speaking machine.

FIG. 319_e_.—_Edison’s Original Phonograph._
]

FIG. 319_f_.—_Diagrammatic Section of Phonograph._
]

FIG. 319_g_.—_The Graphophone._
]

Fig. 319_e_ shows the form of the phonograph as designed by Mr. Edison in 1877. It had a brass cylinder (A) upon which a narrow helical groove was cut, and was mounted upon an axle (B), having a narrow screw-thread corresponding with the groove on the cylinder, and working in the upright (C), so that when the handle was turned the cylinder revolved, and at the same time advanced in the direction of its axis. A heavy fly-wheel (D) was attached, in order that the rate of motion might be nearly uniform. A sheet of tinfoil, or of very thin copper, was wrapped round the brass cylinder, and on this metallic foil rested the steel point attached to the vibrating diaphragm, which was mounted in the ring (F). This point was always adjusted so as to be over the helical groove in the cylinder, and made to touch the tinfoil with a regulated pressure. E shows the manner of firmly supporting the diaphragm in such a manner that it could be readily removed from the cylinder when the latter had to be covered afresh with tinfoil, or the cylinder adjusted for reproducing the sounds. The relation of the diaphragm and point to the tinfoil is shown in Fig. 319_f_, which represents the apparatus in section. The tracing point (_t_) is not attached directly to the vibrating diaphragm, but to an adjustable spring (_s_), and interposed between the spring and the thin metallic diaphragm is a little pad, formed of a ring of small india-rubber tubing. When the mouthpiece (M) is spoken into, the sound vibrations reach the diaphragm (_g g_) through the opening (_o_), and the movements thus communicated to the point (_t_) which indents the tinfoil to various depths, and with varying frequency, as the handle is turned, bringing the whole length of the groove in succession to be operated upon. When the instrument is required to reproduce the speech so easily recorded, all that is necessary is to allow the indentations to re-act on the point that made them. The cylinder is re-adjusted to the tracing point at the end at which it began, the cylinder is set in motion, and the traces made on the tinfoil move the point up and down, the vibrating disc (_g_) following its movements, and thus communicating to the air a system of impulses which are the counterparts in period, force and succession of those that originally entered at _o_. It was usual to attach a conical mouthpiece to the ring (F) in order to concentrate the reproduced sounds, which might then be heard in all parts of a large room. When, in reproducing the sounds, the cylinder was turned with the same velocity as when the words were spoken, the pitch of the voice issuing from the instrument was the same. If it were turned quicker, the pitch was raised; if slower, lowered. The words registered on the tinfoil could be reproduced two or three times, but with decreasing distinctness, as the tracings gradually become obliterated. However, the sheet could be removed from the cylinder, and the speech reproduced at any place at any time afterwards by means of a similar instrument, and a method of stereotyping was proposed for preserving the records. The original phonograph was greatly improved when well regulated clockwork was used for imparting motion instead of the winch. Mr. Edison contrived a modification of the machine, which made it much easier of manipulation, by substituting for the cylinder a flat plate on which a spiral groove was cut. The plate was turned by clockwork, while the vibrating point was made to follow the groove from the centre to the circumference. The phonograph in its original form reproduced speech with peculiarities of its own. The quality was metallic, and reminded one of the intonation of the street Punch. It will easily be understood that the disc itself must necessarily have its own systems of vibration, and these will be further modified by the action of all the other parts. Mr. Edison’s expectations of the capabilities of the instrument not being realized, he turned his attention, after several unsuccessful attempts at its improvement, to the electric light and other subjects, at the same time declaring his conviction that the perfection of the instrument would be but a matter of time; in fact, within a very few years afterwards such improvements were made on Mr. Edison’s instrument as went far to justify this prophecy. These were the work of Dr. Chichester Bell and Mr. Tainter, who, after long continued experiments, found in paraffin wax, with a small admixture of some other substances, a better material for receiving the impressions. A cutting style made to act upon this cuts out a fine groove, the bottom of which is not a series of indentations, but a continuous wavy curve, representing every degree of inflection the vibrating diaphragm. In the new form of the instrument, FIG. 319_g_, which was called the _graphophone_, to distinguish it from Edison’s, the cylinder does not move forward: it is the diaphragm that advances parallel to the revolving axle. The cylinder is driven by a treadle, like a sewing-machine, and there is an ingenious arrangement by which the speed is controlled so that it can be maintained quite uniform. The movement of cylinder and style can be instantly arrested by touching a button, and as readily re-started. Quite recently Mr. Edison has returned to improving the phonograph by using rather thick, solid cylinders of wax, which are previously prepared for use by the instrument itself paring them down to a truly cylindrical and perfectly uniform surface, the result being a great increase of clearness in the speech and tones of music. Mr. Edison’s new instruments are driven by small electro-motors, and the speed is regulated by a centrifugal governor. It is said that these wax cylinders are capable of giving out the same record for a thousand times without perceptible sign of deterioration; and when the cylinders are required to receive a fresh impression, a former one can easily be pared off. The machines can be arranged so as to sound loud enough to be heard by a large assembly; but the quality of the tones of speech or music is most perfect when conveyed from the receiving chamber in front of the diaphragm to one or both of the auditor’s ears by means of a short elastic tube. Half a dozen persons can thus hear the record on the cylinder with such marvellous distinctness as to be able to recognize the tones of a known voice. The very latest form of the instrument, as it has just left Mr. Edison’s hands, is represented in Fig. 319_h_. In this one single very small diaphragm serves both for recording and reproducing the sounds. This is made of extremely thin glass, to which is attached a small projection made of celluloid, which acts on a bar that carries the recording point. The configuration of this point is most ingenious and peculiar, for it is, in fact, double, one part being shaped like a gouge, which cuts into the walls of the minute depression traced on the wax cylinder, while a style-shaped part impresses the wax with punctured indentations. The shaping of its forms is a difficult and delicate operation, for they are very small and are cut in sapphire. The reproduced speech given out by this instrument is said to possess the properties of sharpness and clearness in a remarkable degree. The machine is provided also with a sapphire cutting edge, by which an old record may be pared off by the very motion of the cylinder in receiving a new one. This phonograph is put in movement by ingenious mechanical devices, for giving uniform rotation from such motive power as may be supplied by the foot or by water or by clockwork. This improved instrument lays claim to practical utility, and its manufacture will, it is stated, be shortly commenced on a large scale.

Quite recently there has been established in America a big manufactory of phonographs in the form of a toy, which is sure to become very popular everywhere. Here they turn out daily several hundred _real speaking dolls_, which contain clockwork actuating a phonographic cylinder impressed with the words of some childish story or simple rhyme, such as “Jack and Jill,” “Mary Had a Little Lamb,” etc. Each doll of course repeats its little tale as often as the clockwork is set going. These toys are adapted to all nationalities; for, besides many English, there are a number of French, German, Italian, etc., girls employed doing nothing all day long but addressing appropriate words to each little automaton’s waxen cylinder.

FIG. 319_h_.—_Edison’s Perfected Phonograph._
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The capabilities of the phonograph suggest some curious applications that may be made of it. For example, the songs of a fine singer may thus, in all their modulations, reach people in distant lands, or be made audible to future generations. Thousands of people in England have heard with their ears, through Mr. Edison’s instruments lately brought over by Col. Gournaud, songs and speeches, and pieces of concerted music, sung, said, or played in America months before. Music can be bottled up, so to speak, without the consent of the originators; and, indeed, it is said that an eminent _prima donna_ has applied for an injunction to restrain certain _phonographers_ from reproducing her vocal triumphs with their instruments. A speech of Mr. Gladstone’s, delivered in England, has been phonographically heard in New York with great applause. There is no reason but what, with a loud speaking phonograph uttering an orator’s very words and tones, while instantaneous photographs of his successive gestures and attitudes are projected on a screen, a true and lively impression of his eloquence might be conveyed centuries after his decease. One is almost led to speculate as to the consequences if these nineteenth century inventions had been antedated by a few thousand years: what stores of knowledge we might now possess! and how pleasant it would be thus

To hear each voice we feared to hear no more!
Behold each mighty shade revealed to sight,
The Bactrian, Samian sage, and all who taught the right!

FIG. 320.—_The Domestic Aquarium._
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AQUARIA.

Under the date of May 28th, 1665, the curious gossiping diary of Samuel Pepys contains this entry: “Thence to see my Lady Pen, where my wife and I were shown a fine rarity; of fishes kept in a glass of water, that will live so for ever—and finely marked they are, being foreign.” This doubtless refers to the now well-known gold fishes, which about the time alluded to were introduced into Europe from China, where they had probably been for ages reared and kept in captivity, chiefly for the sake of ornament. Perhaps the reader may be disposed to think that, therefore, the aquarium cannot be distinctively a nineteenth century invention, nor at all a modern invention, in principle at least; but merely the “glass of water,” or the globe of gold fish on a larger scale. Such a notion would be quite incorrect, for the principles which are embodied in the modern aquarium were not recognized and applied until quite recently. Aquatic animals kept for a period in vessels in which the water is changed from time to time cannot be considered as properly forming an aquarium. The beauty and value of a well-regulated aquarium depend not merely on the opportunities it affords of studying the habits of the animals; the spectacle it presents has a far wider interest, as illustrating and confirming the conclusions of science regarding certain great principles which govern the whole animal and vegetable life of this terraqueous globe. Perhaps in the whole range of nature nothing is more wonderful than the direct interdependence of animal and vegetable life, and the exact balance between them, which preserves the composition of the atmosphere unchanged. The constituents of the atmosphere have an immediate relation to both forms of life. No animal can live without a supply of oxygen gas, which it absorbs and replaces by carbonic acid gas. The latter, on the other hand, is absorbed by plants, for these, under the influence of light, decompose the carbonic acid, returning the oxygen to the atmosphere, thus purifying the air by again fitting it for the respiration of animals.

It might be supposed that animals which live entirely beneath the surface of water are removed from the influence of atmospheric oxygen, and that they form exceptions to this law. But such is not the case, for water absorbs and holds in solution a certain quantity of air, the oxygen of which is taken up by aquatic animals. In the lower forms of animals inhabiting water, the absorption of this vital element takes place at the general surface of the body; but in the more highly organized creatures there are special organs appropriated to this purpose, of which the gills of a fish may be cited as a typical example. The giving out of carbonic acid is an action as universal in the animal world as the absorption of oxygen, and all aquatic animals tend to charge the water in which they live with this gas. Fish, or any other water animals, will soon die if they are placed in water from which all the air has previously been expelled by boiling, or by placing under the receiver of an air-pump. In this case the creature dies from want of oxygen; but it would also die, even if supplied with oxygen, were the poisonous carbonic acid emitted by itself allowed to accumulate in the liquid. In nature, this carbonic acid forms the food of aquatic plants and sea-weeds, and these restore oxygen to the water. If a bunch of watercresses be placed in a bottle filled with water, and exposed to strong sunshine, the leaves may soon be seen covered with small bubbles of gas. This gas may be collected and examined by a suitable arrangement of the bottle, and it will be found to be pure oxygen.

The merit of having first imitated the plan of nature for the preservation of aquatic animals appears to belong to Mr. Ward, the inventor of the “Wardian cases” for ferns and other plants. He, in 1841, formed in London a fresh-water aquarium, in which, for the first time, the animals were kept in a healthy condition by the compensating action of plants. Mr. Gosse, Dr. Price, and others, made experiments with marine animals and plants, about 1850. Mr. Mitchell, who was then secretary to the Zoological Society of London, saw about this time a small aquarium on the balancing principle at Dr. Bowerbank’s, and this suggested the erection of the fish-house in the Zoological Gardens, Regent’s Park. This was opened in 1853, being the first public aquarium ever constructed. The tanks remain at the present time in nearly their original condition, and this aquarium has been remarkable, not only as predecessor of the many public aquaria which have since been erected, but for having given rise to a movement in favour of aquaria as domestic establishments. The setting-up of household aquaria became almost the rage of the day, and so many books and magazine articles devoted to the subject appeared during the ten years following the establishment of the Regent’s Park aquarium, that the literature of the subject is quite considerable. Mr. Gosse showed how water for marine aquaria could be produced by adding to fresh water the solid constituents of sea-water; and, in the marine aquaria of some inland towns far distant from the sea, this artificial sea-water is the only kind used. After the establishment of the Regent’s Park aquarium, public aquaria were opened successively in Dublin, Galway, Edinburgh, Scarborough, Weymouth, the Crystal Palace, Brighton, Manchester, and Southport; and on the continent at Paris, Hamburg, Hanover, Boulogne, Havre, Brussels, Cologne, Vienna, and Naples; also in North America at San Francisco, and in other places. The general interest in public aquaria, and especially marine aquaria on the large scale, seemed to increase as the comparative failure of the domestic tanks lessened the taste for them. The causes of the failure so often attending the attempt to maintain aquaria on the small scale arise partly from the amateur naturalist’s want of exact knowledge, and the great amount of attention and care required, and partly from the inherent difficulties of the subject. An aquarium, even on the largest scale, and with every appliance that science can suggest, only represents, after all, _a few_ of the conditions which actually exist in nature; but in small vessels, with a limited quantity of water, without the continual motion of the liquid, which belongs naturally to seas and streams, and with circumstances of light and temperature widely different from those which are obtained in nature, it is not surprising that the success of domestic aquaria should be but very partial, and that the taste for them should have declined accordingly.

Many public aquaria proved commercial failures; but we select for special description two which have been thoroughly efficient, and are remarkable for size, reputation, and successful management. The arrangements at these two institutions as regards the aëration and renewal of the water are, however, quite different. Some plan by which the same sea-water might be supplied with oxygen, and kept in a clear and pure condition, was necessary for the very existence of the inland marine aquarium at the Crystal Palace, whereas the position of Brighton made the natural sea-water more available. The success of the former method at the Crystal Palace Aquarium, under the judicious system adopted by Mr. W. A. Lloyd, the superintendent, perhaps renders this aquarium one of the most interesting, in a scientific point of view, of any yet in operation. The water here is never changed by the addition of sea-water; but fresh water is added as required, simply to supply the loss by evaporation; and any solid constituents which the animals may abstract from the water as material for their shells is replaced, so that the ordinary composition of sea-water is maintained. This is merely imitating Nature, for the evaporation from the surface of the sea is compensated by the fall of rain and the influx of rivers, the latter constantly bringing in the various salts held in solution. The following particulars regarding the Crystal Palace Aquarium are derived from Mr. Lloyd’s excellent handbook, which contains not only clear descriptions of the inhabitants of the tanks, but interesting historical notices and a well-written disquisition on the principles which should regulate the construction and management of aquaria.

_THE CRYSTAL PALACE AQUARIUM._

The building was commenced in July, 1870, and was opened in August, 1871. It was designed by Mr. Driver, of Victoria Street, and presents an admirable simplicity, which entirely accords with the purpose for which it was erected. The whole available space has been occupied, and nothing has been wasted on unmeaning or fantastic embellishments. Even the decorative shams, in which ordinary painters delight, have been excluded. No part of the walls or of the woodwork is painted to look like marble, or even to imitate oak. The building, which is about 400 ft. long and 70 ft. broad, is situated at the north end of the Palace, partially occupying the site of the portion which was so unfortunately burnt down in 1866. It is but one storey high, and besides a large reservoir beneath the floor, holding 100,000 gallons of sea-water, there is a series of sixty tanks, with thick plate-glass fronts, which collectively contain 20,000 gallons of water. This water, weighing over 1,000,000 lbs., was brought from the coast and conveyed to the Palace by the Brighton Railway Company at a very moderate rate. For many weeks after the water was placed in the reservoir and tanks it was very turbid, from taking up the lime used in their construction and in that of the rockwork. In this condition it was very alkaline; but the lime was slowly precipitated by the carbonic acid of the air, the water became clear, and vegetation appeared in the tanks. The great capacity of the reservoir facilitates the cleansing of the water; for, supposing that the water in one of the tanks, holding, say, 6,000 gallons, became turbid from any cause, the water from this tank could be run off into the reservoir, where its mixture with the much larger quantity would not sensibly affect the purity of the mass, from which within half an hour the tank could again be filled.

All the tanks are constantly receiving water from the clear and cool reservoir below, in which there are no animals, so that the motion of the water in the tanks, like that of the ocean, is incessant. The water issues from the pump at a rate (indicated by a counter) of from 5,000 to 7,000 gallons per hour. The pump is worked by a steam engine of three horse-power, and the machinery requires the unremitting attention of three engineers, who succeed each other by turns, each working for eight hours. Two sets of the machinery—pumps, steam engines, and boilers—are provided, one being always kept in reserve, ready for use in case of any accident. Even in winter, when, from the lower temperature, the water contains the largest amount of oxygen, it is found that the stopping of the circulation of the water for only a few hours occasions manifest discomfort to some of the animals. The water is poured into the two centre tanks in an equally divided stream, and by a simple fall of a few inches from tank to tank it flows by two routes to the lowest tank, from which it passes into the reservoir below. This incessant circulation of the water constantly exposes fresh surfaces to the action of the air, by which oxygen is absorbed. But besides this, other small streams of water are made to forcibly enter the tanks from jets, by which a large quantity of air is carried down in very small bubbles. The removal of carbonic acid is accomplished by the vegetation which spontaneously makes its appearance in sea-water under suitable circumstances. It has been found quite unnecessary to introduce purposely any kind of sea-weeds, for the spores of low forms of vegetation are always present in the water, and they develop rapidly under the stimulus of light. Indeed, one of the difficulties of aquarium management is to avoid this excessive vegetation by limiting the light as much as possible, and yet leave sufficient illumination for the observation of the animals. The amount of light falling upon each tank is very carefully attended to at the Crystal Palace, and where it cannot be diminished sufficiently to check the overgrowth of vegetation, without at the same time interfering with a proper view of the animals, certain molluscs and fishes which live upon _algæ_ are put into the tanks to consume them. This spontaneous vegetation is so vigorous that a comparatively small quantity suffices to remove from the water all the carbonic acid which it may derive from the animals and decomposing matters.

It should be mentioned that at this aquarium the water is never filtered, but its clearness is obtained merely by the perfect system of circulation. The unused food and excrementitious matters are oxygenated by the air which the water abundantly holds in solution—thanks to the surface exposed in its constant circulation, the injection of the jets of water carrying minute bubbles of air into the mass of water, and the gas given off by the vegetation. The whole process of purification is therefore chemical, and the success and excellent adaptation of the system may be judged from the fact that the water seen in masses 9 ft. deep appears perfectly clear and bright. The building is very cool in summer: even in extremely hot weather the temperature of the air within it is never higher than 68° F., and that of the water in the tanks never exceeds 63°. In winter the temperature of the air is maintained by hot-water pipes at from 60° to 65°, and the temperature of the water at about 55°. On winter evenings the aquarium is illuminated with gas, and the habits of many nocturnal animals can then be conveniently studied.

FIG. 321.—_The Opelet_ (_Anthea cereus_).
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