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trade longer or Shorter, by Strokes of different Length or Qoicknefs.
This Continuity, is, properly, a Succeffion of fevera] Sounds, or the Effect of fevera] diftinct Strokes, or repeated Impulfes on the fonorous Body, fo quick, that we judge it one continued Sound ; efpecia!ly if it be continued in the fame degree of Strength : And hence arifesthe Doctrine of Meafure and Time. See Time.
Sounds, again, are diftinguifhed, with regard to Mufic, into Simple andtwnpound ; and that two Ways :
In the Firft, a Sound is faid to be Compound, when a Hum* fcer of fucceflive Vibrations of the fonorous Body and the Air, come fo fait upon the Ear, that we judge them the fame con- tinued Sound ; as in the Phenomenon of the Circle of Fire, caufed by putting thefir'dEnd of a Stick in a quick, circular Motion ; where, fuppofing the End of the Stick in any Point of the Circle, the Idea we receive of it there, continues till the Impreffion is renewed by a fuddenReturn.
K fimpie Sound, then, with regard to\ this Compofition, .mould be the Effect of a Single Vibration, or of fo many Vi- brations as are neceffary to raife in us the Idea of Sound. In the Second Senfe of Compofition, a (inrple Sound is the Product of one Voice, or one Instrument, £j?c.
A compound Sound, confiSis of the Sfflnds of feveral diftincf Voices or Instruments all united in the fame individual Time and Meafure of Duration, that is, all finking the Ear together, whatever their other Differences may be : But in this Senfe, again, there is a two-fold Compofition ; a Natural and Jnificial one.
The natural Compofition, is that proceeding from the mani- fold Reflexions of the firSt Sound from adjacent Bodies, where the Reflexions are not So fudden, as to occafion Eccho's ; but are all in the fame Tune with the firfiNote. See Resonance.
The artificial Compofition, which alone comes under the Mu- sicians Province, is, that Mixture of feveral Sounds, which being made by Art, the Ingredient .Sta/w.-^ are feparable,and diftinguifh- ablefrom one another. In this Senfe, the diliinct Sounds of feveral Voices or Instruments, or feveral Notes of the fame Instrument, are called Simple Sounds ; in contradistinction to the Compound ones, wherein, to anfwer the End of Mufic, the Simples muft have fuch an Agreement in all relations, chiefly as to Acutenefs and Gravity, as that the Ear may receive the Mixture with Pleafure. See Composition.
Another Distinction of Sounds, with regard to Mufic, is that, whereby they are faid to be fmooth and even, or rough and harp, alfo clear and hoarfe ; the Caufe of which Diffe- rences, depends on the Difpofition and State of the fonorous Body, or the Circumfiances of the Place ; but the Ideas of the Differences muft be fought from Obfervation.
Smooth and rough Somzds depend, principally, on the founding Body ; Of thefe we have a notable Inftance in Strings that are uneven, and not of the fame Dimenfion or Constitu- tion throughout.
M. 'Perrat/lt, to account for Roughnefs and Smocthnefs, maintains, there is no fuch thing as a fimpie Sound ; but that the Sound of the fame Chord or Bell, is a Compound of Sounds of the feveral Parts of it 5 fo that where the Parts are homo- geneous, and the Dimenfions, or Figure uniform, there is al- ways fuch a perfect Mixture and Union of all the Sounds, as makes one uniform and fmooth Sound : Contrary Conditions, produce Harpnefs. In effect, a Likenefsof Parts and Figure, makes an Uniformity of Vibrations, whereby a great Number of fimilar and coincident Motions confpire to fortify and im- prove each other, and unite, for the more effectual producing of the fame Effect.
This Account he confirms, from the Phenomena of a Bell, which differs in Tone, according to the Part 'tis {truck in ; and yet ftrikeitany where, there is a Motion over all the Parts. Hence, he confiders the Bell as compofed of an infinite Number of Rings, which, according to their different Dimenfions, have different Tones ; as Chords of different Lengths have ; and when {truck, the Vibrations of the Parts immediately Struck, fpecify the Tone, being fupported by a fufficient Number of Confonant Tones in other Parts. This muft be allowed, that every Note of a ftring'd Inftrument, is the Effect of feveral fimpie Sounds : For there is not only the Sound refulting from the Motion of the String; but that from the Motion of the Parts of the Inftrument, which has a considerable Effect in the total Sound, as is evident from hence, that the fame String on different Violins, founds very differently.
"ButTerrault affirms the fame of every String in itSelf, and without confidering the Inftrument. Every Part of the String, he fays, has its particular Vibrations, different from the grofs and fenfible Vibrations of the whole; and thefe are the Caufes of different Motions and Sounds in the Particles, which uniting, compofe the whole Sound of the String, and make an uniform Composition, wherein the Tone of the particular Part Struck, prevails; and all the others mix under a due Subordination with it, fo as to make the Compofition fmooth and agreeable. If the Parts be unevenly, or irregularly constituted, the Sound is harm ; which is the Cafe in what we caWfalfe Strings, and
various othef Bodies; which, for this Reafon, have no certain and diltmct Tone; but a Compofition of feveral Tones, which don t unite and mix, fo as to have one predominant, to Specify the total Tone,
As to clear and hoarfe Sounds, they depend on Circumstances that are accidental to the fonorous Body: Thus a Voice or Inftrument will be hollow and hoarfe, if raifed within an - empty HogfJiead, that yet is clear and bright out of it : The Effect is owing to the Mixture of other and different Sounds, raifed by Reflexion, which corrupt and change the Species of the primitive Sound.
For Sounds to be Sit to obtain the End of Mufic, they ought to be fmooth and clear, efpecially the Sirft ; Since without this, they cannot have one certain and difcernabte Tone, capable of being compared to others, in a certain relation of Acutenefs, of which the Ear may judge ; and of Confequence can be no Part of the Object of Mufic. Upon the whole, then, with Mr. Malcolm, we call that a harmonic or mtifical Sound, which being clear and even, is agreeable to the Ear, and gives a cer- tain and difcernable Tunc; (hence called tunable Sound) which is the Subject of the whole Theory of Harmony. See Harmony.
Sound, in Geography, a Streight, or Inlet of the Sea, between two Capes or Headlands. SeeSTREtCHT.
The Word is particularly ufed, by way of Eminence, for that famous Streight, which joins the German Sea to the Baltic.
It is Situate between the island of Zeland and the Coaft of Schoven. 'Tis about Sixteen Leagues long, and generally five broad, excepting againft the CaStle of ' Cronmbourg, where 'tis but one : So that there is no Paffage for Veffels, but under the Cannon of the Fortrefs.
This has given occafion to the Danes to fettle a Toll on all Veffels, which is one of the heft Revenues of the Crown of "Denmark ; and to forbid all Pilots from pafling through the great and little Belt, which are two other Inlets into the 'Baltic, though fomewhat lefs commodious than the former. The S-wedifJ Veffels are exempted from paying this Toll, by the Treaty of 1658, whereby the Danes "yielded South* Gothland to the Swedes. SeeTorx.
SOWSD-Board, the principal Part of an Organ, and that which makes the whole Machine play. See Organ.
The Sound-board or Summer, is a Refervoir, into which the Wind drawn in by the Bellows, is conducted by a Port-vent, and hence distributed into the Pipes placed over the Holes of its upper Part. This Wind enters them by Valves, which open by preffing upon the Stops or Keys, after drawing the Registers, which prevent the Air from going into any of the other Pipes, but thofe 'tis required in.
Organs, whofe longeft blind Pipes are four Foot, have their Sound-Board from five to fix Feet. Organs of 1 6 Feet have two Sound-Boards, which communicate the Wind from one to the other, by a Pewter Port-vent.
SOUNDING, in Navigation, the trying of the Depth of the Water, and the Quality of the Bottom, by a Line and Plummet, or other Artifice,
There are two Kinds of Lines occafionally ufed in Sounding the Sea ; the Sounding Line and the deep Sea Line.
The SirSt, is the thickest and fiiorteft, as not exceeding 70 Fathom in Length ; and marked at two, three and four Fa- thoms, with a Piece of black Leather between the Strands ; and at Five, with a Piece of white Leather.
The Sounding Line may be ufed when the Ship is under Sail, which the deep Sea-Line cannot. The Plummet is ufually in form of a Nine-pin, and weighs 18 Pounds ; the End is frequently greafed, to try whether the Ground be Sandy or Rocky, lyC Near Banks, Shores, $$c. they are Sounding continually.
Dr. Hook has invented a manner of Sounding the Depth of the deepeSt Sea, without any Line ; only by a wooden Globe, lighter than Water, to which, at a little Diftancc is a piece of Lead or Stone Six'd, by means of a fpringing Wire in the Firft, fitted into a Staple in the Second. The whole being let gently down, with the Stone or Lead foremoSt, affoon as that arrives at the Botom, it will Stop ; but the Ball, by the Impetus it has acquired in deScending, will be carried a little lower after the Weight is ftopp'd ; by which means the fpringing Wire will be inabled to flv back, and difingaging itfelf, will re- afcend.
By obferving, then, the Time of the Ball's Stay under Water by a Watch or Pendulum, and the Help of fbmc Tables; the Depth of the Sea is found.
In fome Experiments made in the Thames with a maple Globe, 5 \\ Inches in Diameter, and weighing 4 Pound and a Half, lined with Pitch ; and a conical Weight n Inches long, the Sharp End downwards ; at the Depth of 19 Feet, there pafled fix Seconds ; and at the Depth of 10 Feet 3 ^ Se- conds between the Immerfion and EmerSion of the Ball. From thefe Numbers given, the Depths, at any other Stays, may be computed by the Rule of Three.
SOUP, a kind of Potage made of Bread, and Broth or [Cc] the
