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fere ; it being very unusual, from motives of delicacy, for a | for the remainder of that fourteen years; but in all cases, peer to support his own judgment on appeal to the House whether he has or has not assigned, to his personal repreof Lords. 'It is somewhat remarkable, that although this sentatives for another fourteen years. They afterwards becould be hardly termed a decision, as the judges were in come public property. 3. The published works of any point of fact divided equally, it has since been held so im- author at that period living, but who dies more than fourportant as a precedent and sustained in so many subsequent teen, and less than twenty-eight years from the date of cases, that it must now be considered as settled law that publication, go to his assignees if he has assigned, and to perpetual copyright is put an end to by the statutes. his personal representatives if he has not, for the residue of

The two universities were not slow to protect themselves the twenty-eight years. They afterwards become public from the consequences of this decree in the case of Donald- property, as they are at his death if he survive twenty-eight sons and Beckett, and obtained from Parliament, in 1775, years. 4. The published works of any author at that period the following year, an act for enabling the two universities living, more than twenty-eight years having then elapsed since in England, the four universities in Scotland, and the seve publication, are unaffected by the act, and continue, as they ral colleges of Eton, Westminster, and Winchester, to were before, public property. Such is the law with regard to hold in perpetuity their copyright in books given or be works published before the passing of the 54 Geo. III., c. 156; queathed to the said universities and colleges for the ad- with regard to works published since it is as follows :vancement of useful learning and other purposes of educa- 1. If an author does not assign his interest in the work, tion. This protection, sanctioned by penalty and forfeiture, and lives more than twenty-eight years after publication, so long as such books are printed at ihe presses of the uni- the copyright remains his for life, and after his death beversities and colleges respectively, is still enjoyed, unaffected comes public property. the author does assign by the general statutes ou the subject; and a similar protec. his interest, the copyright attacles to his assigns for his tion is extended to the university of Dublin by 41 Geo. III., life; and if he die within twenty-eight years, it attaches to

them for the remainder of that term.' It afterwards beThe chief provisions of the 8 Anne, c.19, entitled 'An act for comes public property. 3. If the author does not assign the encouragement of learning, by vesting the copies of his interest, and dies within twenty-eight years from pub. printed books in the authors or purchasers of such copies lication, the copyright attaches to his personal representaduring the times therein mentioned,' as regards the effect- tives for the remainder of that term. It then becomes ing of that purpose, were, that the authors of books already public property. printed, and those claiming under the author, should have It has been said that the exclusive property of authors in The sole right and liberty of printing them for a term of 21 their manuscripts has always been recognized by the law. years and no longer ; and that the authors of books to be But this principle extending only to prevent the printing or printed, and their assigns, should have the same right for circulating copies of them without the license of the 14 years and no longer. And the last clause of the statute owner, it was found necessary to pass recently a statute for directed that after the expiration of these 14 years the same the peculiar protection of the authors of dramatic composiright should return to the authors, if living, for another 14 tions. This is the 3 Will. IV., c. 15, entitled · An Act to years. The persons infringing these provisions were to be amend the Laws relating to Dramatic Literary Property, punished by forfeiture of the pirated book to the proprietor, which, after reciting the 54 Geo. III. c. 156, provides that and a penalty of one penny for each sheet, one-half to go the author of any dramatic piece, not hitherto printed or to the crown and the other half to the informer, provided published by authority of him or his assigns, shall have always the title to the copy of the book had been duly as his property the sole liberty of representing it, or causing entered with the Stationers' Company.

it to be represented, at any place of dramatic entertainment; The 41 Geo. III., c. 107, which extended the same law and the author or assignees of any such work, printed and to Ireland, gave a further protection to authors and their published within ten years before the date of the act, shall assigns by action for damages and double costs, and raised ve the same privilege for twenty-eight years from publithe penalty per sheet to three pence, to be divided in the cation, and for the remainder of the author's life, if he longer sinne way,

live. The penalty for violating these enactments is to be enThe si Geo. 111., c. 156, by which literary property is at forced by action for damages, with double costs, to be brought present mainly regulated, is entitled . An act to amend within twelve months from the commission of the offence. ihe several acts for the encouragement of learning by se- There are certain works excepted from the benefit of the curing the copies and copyright of printed books to the law of copyright from the nature of their contents. Such authors of such books and their assigns. By the fourth are, all publications injurious to public morality, inimical section of the act, after reciting the statutes of 8 Anne and to Christianity, or stimulating, either as libellous or sedi41 Geo. III., by which authors and their assigns had the tious, to a breach of the peace. This must however be unsole liberty of printing for 14 years and no longer, and after derstood of their general tenor, and not of isolated pasreciting that it will afford encouragement to literature if sages. As far as a rule on the subject can be laid down, it the duration of copyright were further extended; it is ! is, that any work containing matter for which a public inenacted, that after the passing of this act, the author of dictment or private prosecution could be sustained is not any book, and his assigns, shall have the sole liberty of print- protected by the law, but may be pirated by other parties ing and reprinting such book for the full term of 28 years at pleasure, who, if sued for penalties under the aet, are from the day of publication, and, if the author shall be living allowed to give in evidence the nature of the composition at the end of that period, for the residuo of his natural life. which they have published, in order to defeat the action.

With regard to books at that time already published, it This is a remarkable exception to the general rule of law, is enacted that if the authors then living should die before that none shall take advantage of his own wrong; and its the expiration of fourteen years from publication, their re- operation is quite as remarkable, the effect of the rule presentatives should have the benefit of the second fourteen having often been to disseminate more widely that which years; and if the authors should survive till twenty-eight the law has declared not to merit protection. years from publication, themselves should have the benefit The protection given to authors by the statute of copyfor the remainder of their lives. But the rights of all right is coupled with conditions of some particularity, alassigns are saved in both cases.

though it is by express words in the fifth section exempted The penalties for tne infringement of copyrights are the from depending on them. Besides the registry at Stationers' same as in the former statutes, but with the limitation that Hall, which is to be made within one month for books puball legal proceedings under the act must be commenced lished within the bills of mortality, and within three months within one year.

for all others, at a penalty of five pounds, and eleven times The results to be collected from the statute, and from the price of the book, the 54 Geo. III., c. 156, requires that subsequent decisions upon it

, as far as protection, to the eleven copies of every work shall be delivered on demand rights of authors is involved, may be briefly stated thus, as in writing within twelve months for the use of the British a summary of the existing law.

Museum, Sion College, London, the Bodleian Library at 1. The published works of any author deceased before Oxford, the Public Library at Cambridge, the Library of the 29th July, 1814, are wholly' unaffected, and at this Advocates at Edinburgh, the libraries of the four Scotch time public property. 2. The published works of any au- universities, and the libraries of Trinity College and the thor at that period' living, but who died within fourteen King's Inns, Dublin. It has been decided, and the deciyears from the time of first publication, go after his death sion is most important, as affecting many works of the to benefit his assigns, if he has assigned his interest therein, greatest value and expense, that works published in parts

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or numbers are not liable to this tax_until completed. | as regards the incorporeal right in them accruing to the 2 Younge and Jervis, 166; 4 Bing. 540. Farther, by a very author by the exertion of his mental powers in their prorecent statute, 6 and 7 W. IV., c. 110, the 54 Geo. III., c. 156, duction, but differ as they also require a good deal of his is repealed, so far as relates to the delivery of copies of manual skill and labour, and are therefore his property books to the four universities of Scotland, Sion College, upon the same general principles as any other manufacture, and the King's Inns, Dublin, compensation being given Such productions therefore are even more plainly entitled to those institutions upon an estimate of the annual value to the protection of the law than books. of books supplied upon an average of three years, ending The chief statutes affecting the copyright in works of the 30th of June, 1836.

design, engraving, and etching, are the 8 George II., c. 13, Besides the special copyrights of the universities secured which vests it in the inventor, designer, and proprietor, for to them as before mentioned by statute, there still exist fourteen years from the first publication, and enforces this certain prerogative copyrights attaching to the owners in provision against any person pirating the same by forfeiture perpetuity. Of these the chief belong to the king, which of the plate and prints, and a fine of five shillings for each were more numerous and considerable formerly than at print, to be recovered by action within three months of the present. Many are now quite obsolete, such as those of discovery of the offence. The 7 George Ill., c. 38, exalmanacs, law-books, and Latin grammars; and others very tends the term of copyright to twenty-eight years; and in questionable, such as that of the exclusive right to print addition to the subjects of the former statute includes

maps, the English translation of the Bible. The king has a pre- charts, and plans, under the same conditions. It also rogative copyright in the liturgy and other services of the extends the time of bringing an action for the penalties to church, in proclamations, orders in council, and other state six months. The 17 George III., c. 57, gives the owner of papers, and in the statutes. It has been decided, that the the copyright a further remedy of action for damages and University of Cambridge shares by letters patent in the double costs within the same limits of time. king's prerogative of printing acts of parliament. The With regard to models, casts, and other sculptures, the House of Lords also exercises an exclusive privilege, some- 38 George III., c. 71 vests the right and property in these what fallen into disuse, of publishing its own proceedings for fourieen years in the proprietor, and gives him a special as the supreme court of judicature.

action on the case against the offender, if brought within The usual modes of legal proceeding tợ prevent or six months. These provisions were rendered more effectual punish the infringement of copyright, or as it is more by 54 George III., c. 56, by which double costs were given, usually termed, piracy, are by action for damages, or for and an additional term of fourteen years superadded in case the penalties given by the statute; or more commonly still, the maker should be living at the end of the first term. by obtaining an injunction in equity to prohibit the un- As to sculpture certainly, but more doubtfully as to prints, lawful publication, which affords immediate and summary for there have been contlicting decisions on the point, the redress. This is always granted where the legal title of the work must bear upon it the name of the maker and the plaintiff to the work is made out, and the identity of the date of publication to entitle it to the protection of the law. pirated publication with his own shown to the satisfaction The right of patents also presents many legal features of the court. The proof even of an equitable title has been analogous to those of copyright, but this subject requires hell sufficient to qualify him for this remedy. Mawman

a separate notice. [Patent.) v. Tegg, 2 Russ. 385. Neither will the court be restrained COQUIMBO. (Chile.) from granting ihe injunction, by proof that the matter COQUIMBO, a town of Chile, and the capital of the pirated forins only a part of the publication complained of, province of Coquimbo, about seren miles from the bay of and that what is original will be rendered useless to the Coquimbo, was founded in 1544 by Don Pedro Valdivia, defendant and the public by prohibiting its sale. But as who called it La Serena, by which name it is still somethis mode of proceeding presses very severely upon de- times known. It is a poor town, with a population which fendants, and often inflicts irreparable injury, the court, has been estimated at 10,000 souls; but other estimates rewhere any doubt attaches, will either refuse the injunction duce it to 4000. The streets are all at right angles to each altogether, or grant it only on condition of the plaintiff's other, of moderate width, but very dirty, the houses, which bringing an action immediately, to have the merits of the are generally of one story, have small gardens attached to case decided by a jury with the smallest possible delay. them, owing to which circumstance thie town occupies a

These legal protections are for the most part found much greater surface than the population would lead one to effectual in restraint of domestic piracy. But over the expect. It contains six or seven churches and a public frequent and daily-increasing practice of foreign piracy, by hospital. The Puerto, or port, is nothing more than a colreprinting English works abroad, they exercise no useful lection of about a dozen miserable huts, with a custom control, although the 54 George III., c. 156, expressly in-house, situated at the head of a smail indentation of the cludes within its prohibitions the importers of foreign coast open to the northward. No fresh water can be proeditions, and the sellers of them with a knowledge of their cured, and supplies of all kinds are scarce and dear. There origin. Notwithstanding this, most popular productions of are no foreign importations direct to Coquimbo: supplies English authors are immediately reprinted in France and are obtained from Santiago or Valparaiso. From 500,000 Germany, and are to be obtained in England at little more to 550,000 dollars are annually exported to Europe in than their original cost. A practice so destructive of the British men-of-war, besides gold; but the duty on this fair profits of mental labour can only be effectually redressed article being very heavy, it is always smuggled on board, by prevailing on foreign countries to extend the benefit of and consequently no estimate of the quantity shipped can their own laws against literary piracy to alien as well as be formed." The port is in 29° 57' S. lat., 71° 17' W. long., native authors. With respect to America, a memorial has about 200 miles north of Valparaiso. recently (1836) been transmitted from this country to Con- The district abounds in mines of gold, silver, copper, and gress, praying for some law to protect English copyright iron: the iron is not worked, on account of the scarcity of fuel. in the United States. Many English works are reprinted COR CA'ROLI, a name given by Halley to the star of in America; and the reprints may be, and frequently are, the third (or 24) magnitude in Canes Venatici, in memory with a little contrivance sold in England at lower prices of Charles I. It is situated on the neck of the lower dog, than the original publication. In this instance the Eng- and, when figured, has a heart surmounted by a crown. lish author loses in another way: bis English edition, The name is not much in use among astronomers. which would sell in America, is supplanted there by an COR LEO'NIS. (REGULUS.] American reprint, which costs the publisher only paper and CORA'CINA, a genus separated from the crows by printing. The American author suffers in the same way in Vieillot, and divided by him into four sections. The first England. Some arrangement therefore between these two comprises those species which have the bill furnished at its countries for the extension of copyright would often make base with velvety feathers (Les Col-nus, naked necks); the a book twice as valuable to the author, and would of course second those whose nostrils are covered with setaceous fea be for the benefit of the reader, as it might be published thers, directed forwards, and whose upper mandible is at a lower price

notched towards the end (Les Choucaris, Graucalus); the A notice of the law of copyright would be incomplete third those whose bill is naked at the base, and notched at which did not advert to some other compositions which re- the point (Coracina gymnocephala, Vieill., Corvus calvus, ceive from statute a protection analogous to that of literature. Latham, for example); and the fourth, that curious species Such are engravings, etchings, and prints, maps and charts, on which Geoffroy St. Hilaire founded his genus Cepha. and sculpture of all kinds. These resemble written works lopterus.

Cuvier, in the last edition of the Règne Animal,' defines or, as some authors write it, Capuchin colour, whence the Graucalus to be the Greek name of an ash-coloured bird Creoles of Cayenne give it the name of 'Oiseau mon père." (oiseau cendré), and says that three Choucaris out of four The quills and the tail-feathers are black. The large beak are of that colour. M. Vieillot, he adds, confounds these and ample forehead bare of feathers give a singular air birds with his Coracinæ, which comprise the Gymnoderi to this bird. Vieillot observes that it has been compared and the Gymnocephali.

to the rook, on account of the nakedness of the head, a M. Lesson, who places the group under the Ampelidæ, comparison which seems to him just ; 'for,' says Vieillot, observes that the genus Coracina is far from being deter- 'it has not this part naked till it is adult, the young, like the mined. Thus, he observes, M. Vieillot places under it the young rook, having the head entirely feathered, and even Cephalopterus of M. Geoffroy-Saint-Hilaire, the Choucari, the nostrils covered with small setaceous feathers, as I can and the Col-nu, or Gymnoderus. (He might have added testify, from the inspection of a young individual, of which the Gymnocephalus of Geoffroy and Cuvier.) Temminck I have made mention in the first edition of the Nouveou adds to it many of the Cotingas of Le Vaillant; but for his Dictionnaire d'Histoire Naturelle.' Locality, Guiana. own (Lesson's) part, he adopts the term Coracina for that group of birds which Cuvier has collected together under the name of Piauhaus.

Genera. Coracina, Lesson. (Coracina, Temminck;

Les Piauhaus, (Cotinga) Cuvier; Piauhau, Querula,

Vieillot.) Bill depressed, smooth, ciliated at the base, thick, narrowed at the point, angular above, a little curved towards the end, slightly toothed at the point; lower mandible a Jittle flattened below; head and neck feathered, but without any ornamental plumes, and

without any naked skin. Example. Coracina scutata, Temm. Coracius scutata, Lath.

This species differs but little from Coracina rubricollis, Muscicapa rubricollis of Gmelin, in the colour of its plumage; but the wings are shorter. In C. rubricollis the plumage is all black, with the exception of the throat and front of the neck, which are of a purpled rose-colour. In C. scutata the red, which covers the throat and breast, goes as low as the upper part of the belly, and the bill is not black, as it is in C. rubricollis. Locality, Brazil, which is also the habitat of C. rubricollis.

[graphic]
[graphic]

(Gymnocephalus calvus.]
Gymnoderus. (Coracina, Vieill., Temm. Cotinga,

Le Vaill.)
The principal characters of Gymnoderus, Geoffroy-Saint-
Hilaire, rest on the possession of a bill like that of the
Coracinæ and Cephalopteri, with a partially naked neck
and a head covered with velvety feathers.

Example. Gymnoderus fætidus, Coracina gymnodera, Vieill., Corvus nudus, Lath., Gracula nudicollis, Shaw., Gracula fætida, Linn., Col-nu, Buff. Rather larger than the jackdaw, but the body is thick and fleshy. The sides of the neck are entirely naked, and only present some traces of down. Buffon's figure, on the contrary (Planches

[graphic]

(Coracina seutata.) Gymnocephalus. (Coracina, Vieillot.) M. Lesson observes that MM. Vieillot and Temminck place the Gymnocephali (Bald heads) among the Coracina, and that Cuvier contents himself with observing that Corvus calvus, Latham, the type of this new genus, has the bill of the Tyrants, with the ridge (culmen) a little more arched, and a great portion of the face denuded of feathers. Le Vaillant, he states, regarded this denudation of the skin in the front of the head as the result of a particular habit, and in the History of the Birds of Paradise' has printed a note, in which ho affirms that he had received from Cayenne a specimen, having this part well covered with feathers; bui, M. Lesson adds, that he himself had seen at Rochefort more than twenty skins of Gymnocephali, and that all had the face bare of feathers. However it may be, he continues, this genus entirely requires revision,

Examplo Gymnocephalus calvus, Coracina gymmocephala, Vieill., Corvus culrus, Lath., Capuchin BaldHead. Size of the crow, and of the colour of Spanish snuff,

(Gymuoderus fætidus, male.

is naked.

enlum. 609), represents this part as being clothed with a bill, as Temminck represents them, partly repose and overconsiderably thick down. Upper part of the head, back of shadow it, at least as much as do those of Całyptomena and the neck and throat, covered with small close-set feathers Rupicola (vol. i. p. 41).' The species above noticed is the like black velvet. External edges of the quills of the mid- only one known. dle of the wing, the last quills, and all the wing coverts, ČORAL. (POLYPARIA CorticiFERA.] bluish grey. Great quills and tail-feathers black, with CORALLIA. (POLYPARIA CORTICIFERA.] bluish reflections. The rest of the plumage, bill, and feet, CORALLINES. [PSEUDOZOARIA.] black. Eyes red brown, with a yellow skin beneath. The CORANTO, a qui dance. (Courante.] female is smaller, and of a brownish black. Locality, CORBEL, a projecting piece of stone, wood, or iron, Brazil and Guiana.

placed so as to support a weight of materials. Corbels are Cephalopterus.

sometimes in the form of the modillion or mutule emBill strong, robust, mandibles nearly equal, the upper | dow. Small semicircular towers projecting at the angles

ployed in entablatures, and also like the console of a winone convex and scarcely curved at the summit, not notched on perpendicular surfaces of large towers or other edifices at the point ; lower mandible flattened below. Nostrils are supported on a series of plain or moulded corbel stones. longitudinal, open, hollowed into an oval excavation ; In some of the colleges in Oxford and Cambridge the bristles at the border of the bill, which infringe a little on mullions and roof of semicircular windows are supported the frontal feathers. Two rows of feathers, taking their in the same manner. The machicolations of towers are origin on the forehead, and elevating themselves into a almost always supported on corbel stones, as may be obplume or crest on the head. The feathers of the neck served in the old gates of Southampton, Canterbury, and form a kind of pendant pelerine in front of the neck, which York. This projecting of one stone beyond another is tera, Vieill. Colour a uniform blue black. Head and base churches the construction of the roof appears to be sup; Example. Cephedopterus ornatus, Coracina cephalop- technically

called corbelling

out. This is done in brick

In the interior of some of the bill ornamented with a plume or crest, forming a sort ported on corbels, the ends of which are often carved, and of parasol, composed of straight elevated feathers, with white represent an angel holding a shield. In Norman archiand stiff shafts, and terminated by an ear (épi) of black tecture the cornice is supported by a row of corbel stones, beards, which projects forwards (se renverse en devant). the ends of which are also carved. In old English castles The sides of the neck are naked, but long feathers form- the main beams of the floors were frequently carried on ing a loose pelerine, and hanging down lower than the large corbel stones, as at Porchester Castle. The term breast, spring from beneath the throat and from the sides bracket is sometimes used for a corbel. Bracket lowever of the neck. Tail long, slightly rounded. General plumage is better applied as synonymous with cantilever. Small of a deep black. Crest and feathers of the pelerine giving wooden brackets often differ from corbels and cantilevers metallic reflections (Lesson). The bird that furnished the description was brought to and not having a bearing on a wall, as is always the case

in being merely nailed to a perpendicular piece of wood M. Geoffroy-Saint-Hilaire from Lisbon. M. Lesson states with corbels and cantilevers. that the belief was that it came from Brazil, but that a wellinformed Portuguese had told him that it was from Goa. modern island of CORFU. Though the name is written

CORCY'RA (Kép«upa, Kerkúra), the Roman name of the M. Vieillot says that the colour of the naked skin of the Kerkura in the Greek authors, it seems that all the extant neck is cerulean blue. Mr. Swainson, in his Natural His- coins have KOPKYPA (Korkura). (CORFU.] tory and Classification of Birds, London, 1836, says, “The crest of this extraordinary bird is immensely large, advancing so far in front as to touch the end of the bill, and it is compressed in the same manner as that of Rupicola ; but the ends of the feathers, instead of meeting so as to form a sharp ridge, suddenly recede from each other, curve outwards, and form a most elegant drooping line of plumes, hanging over on the sides, so as to shade the face like an umbrella. The figures that have hitherto been given of this rare bird are all taken from the specimen in the Paris British Museum. Actual size. Silver. Weight, 76 grains. Museum, and which has been sadly distorted in the setting up. A minute examination of this specimen has convinced fixed at the two extremities and stretched with force suffi

CORD, frequently spelt chord, means an elastic string us that the frontal feathers, instead of being raised over the cient to enable it to yield a musical note. (Acoustics, vol.

i., p. 97. Throughout this article A means the article Acoustics, and the page and column of vol. i. are referred to.] The close analogy which exists between a string and a column of air in a state of vibration would require more space to elucidate properly than this subject will allow us to give: we shall therefore assume some results of mathematical reasoning, point out the probability of those results, and consider the theory of the vibrating cord independently.

Firstly, we suppose our cord to be of uniform thickness and density, so that any given length is precisely of the same quality, from what part soever of the string it may be cut. The want of this condition being practically fulfilled is sometimes sensibly felt in violin and violoncello strings, which are then called false. A player whose intonation is perfect upon a perfect string, has to learn a new instrument when he attempts to play with a false string; to say nothing of the harmonics which must be heard more or less becoming discordant.

Let us first suppose a string of indefinite length, and not so acted upon by gravity as to hang downwards, stretched at the two ends by equal weights. The string is a cylinder of uniform diameter and density. Let us next suppose that a part of the string is placed on a mould which catches two points and holds them fast, and stretches the intermediate part into a curve which differs very little from a straight line. Let the mould be suddenly removed, and let us further suppose that, in removing it, we are able to communicate any velocities we please to the different points of the

stretched part. We have then, at the moment of starting, [Cephalopterus ornatus.

a system represented in the following diagram, where AB

.(Coin of Corcyra.]

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C

RCR

T

T

N

N

B

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R

А

N

к

B

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in

B

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G

P

A

H

D

this are two of the form A c B, such that at any point R (dotted) represents the part in question before the mould the velocity would bring the point through RN while the was applied, and it is ACB the instant the mould is taken disturbance is communicated through AN. If we suppose away, all the points between A and B being in a state of a direct and retrograde disturbance of such a kind, there motion upwards or downwards. The string will not remain will be at the first moment no velocity at any point of ACB. an instant in its present state: the first presumption is that since those of the direct and retrograde disturbance com: the moment the points A and B are set free a distui bance will take place in the parts of the string both between P and A, and between Q and B, the disturbance travelling from A towards P as well as from B towards Q. The first point in which we are interested is this: with what velocity will the disturbance be propagated ? and the answer is, that pensate each other throughout. But let a time elapse the disturbance travels throughout the string with the same during which the direct and retrograde disturbances travel Velocity, depending upon its material and the weight with to M and L. Then the form of the string at that moment wh.ch it is is stretched, according to the following law: will be Acmn c B, where the part m n arises from the Let each of the equal weights Pand Q be as heavy as c fuet composition of the two parts of the disturbances which of the string : then the velocity of communication is so set remain acting on the same points. (See another in many feet per second as a bullet would acquire, if it were stance of composition, A. 92.) allowed to fall in vacuo down a perpendicular of c feet, or

We may thus trace the effect of disturbance upon an in

definitely extended string; but such a string would proN2 gc where g is the velocity which gravity communicates duce no niusical sound, for which (A. 95,2) it is necessary in one second, or 324 feet. For instance, let the string be that there should be a continued reiteration of the same iron wire, every cubic foot of which weighs 7200 ounces avoirdupois . Let the diameter be one-twentieth of an inch, posing a finite string, stretched at the ends, we must ask

action upon the air repeated at equal intervals. Now supand let the weights P and Q be each 20 pounds or 320 / what takes place when the disturbance comes to the end of ounces. Then the weight of x feet of the string is (3of an the string." And from mathematical analysis again, the inch being to of a foot)

following is the answer: Let P be the fixed end of the 3:14159 X (113) x x x 7200 ounces which made equal to 320 gives x = 3259-5 feet and

12 X 323 3259.5 = 457.93 = 158 nearly, or 458 feet per second is the rate at which the disturbance is communicated. [CYLINDER.)

We now ask what is the nature of the disturbance communicated. It suggests itself as possible, that there may be some species of disturbances which travel only in one direction: for instance, that we might so proportion the velocities of the disturbed points to their positions, that AP should remain undisturbed, that the points from A towards the right should drop one after another into their places, while those from B to Q should be successively disturbed. The answer, again derived from mathematics, is, that such disturbance is possible, and that the conditions under which it will take place are: 1. That C being the highest of the disturbed points, all the points from A to C must be moving downwards at the first instant, and all those from B to Q | string, and choose the instant at which, had the string con. upwards. 2. That the velocity of the points must be as follows: At any point R draw a tangent RT to the curve disturbance H A' equal and opposite to G A, and let it be

tinued, the disturbance would have been BV A. Make a of disturbance. Then the velocity of the point R must be compounded with G V B, on the supposition that it is part such as would, if continued uniformly, carry the point R of a disturbance proceeding from P, such as would by itself from R to N or from N to R in the same time as the whole bend the string in the opposite direction. Then P V B or disturbance is propagated from T to N. These conditions PV A' is the state of the siring at that instant. In fact, being fulfilled, we may represent the successive states of the disturbance is converted into an equal and opposite the string by cutting out a piece of paper of the form ACB, disturbance proceeding in the contrary direction. and carrying it along the string PQ at the uniform rate per second which we have found for the propagation of the sharply struck near one end. It is altogether a gratuitous

Now let us suppose a string like that of a piano-forte, disturbance. If the directions of the velocities be all re-assumption, knowing what we do of the imperfect elasticity verser, then the disturbance travels from B towards P. Let of matter, to suppose that the disturbing effect of the blow us call such disturbances simple ; and with respect to the immediately affecis the whole string. A certain disturbdirection in which they travel, direct or retrograde. We ance is produced upon a part (it may be a very small part) further learn from mathematical analysis, tbat any dis- of the string. Then what is that perceptible phenomenon, turbances whatsoever, taking place upon the same points the reiteration of which produces a inusical tone? Let us at the same instant, produce a compound disturbance of suppose the string struck at one-fourth of the length fiom which the values of RN and the velocities at the point R in iis end, and suppose that the tension is such that disthe compound disturbances are the algebraical sums of the turbance is propagated at the rate of 2000 feet a second, the values of RN, &c., in the component disturbances. And length being four feet. A disturbance is produced at M, moreover, that any disturbance whatsoever, be the law of its form and velocities what it may, can be compounded of two simple disturbances, one direct and one retrograde. So that the moment the mould is removed, the disturbances will begin to travel in different ways. As long as they have from which two simple disturbances begin to travel 10not completely separated, there will be points remaining wards P and Q, at which they are reflected with the sume under the effects of both; but when they have had time to velocities. They will be at N together producing a diss separate completely, we should, were the rapidity of trans- turbance (now recompounded) of the same amouni as bemission not too great, see the direct disturbance travelling fore, but on the opposite side of the string. This takes by itself in one direction and the retrograde in the other. place while four feet are described at 2000 feet per se ond, or

To illustrate this, suppose we wish to ascertain the effect is repeated 230 tiines per second. From M 1 N there is of the disturbance ACB, as drawn, the velocities through-then a succession of eifects upon the air, which are cost out being nothing at all at the instant the mould is with powerful at M and N, owing to the coincidence of the disdrawn. The two simple disturbances which would produce liurbances. This is repeated 250 times in a second, and

B

PI

H

1

M

N

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