Page:Cyclopaedia, Chambers - Volume 2.djvu/921

 TUN

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T U R

Y tie only tliffcrence, then, between one Tune and another is, in Degrees; which is naturally infinite, /, e. we conceive there is fometh'ing pcfitive in the Caufe of Sound which is capable of lefs and more, and contains in it the Meafure of the Decrees of Tune 5 and becaufe we don't fuppofe a leaft or created Quantity of this, we conceive the Degrees depend- ing on thofe Meafures to be infinite. See Sound.

'If two or more Sounds be compar'd together in this Rela- tion, they are either equal or unequal in the Degree of Tune. — Such as are equal are calPd TJnifons. See Unison.

The unequal conftitute what we call an Interval, which is the Difference of Tune between two Sounds. See Inter- nal.

Caufe and Meafure of Tune 5 or that whereon the Tune of a Sound depends*

Sonorous Bodies, we find, differ in Tune, i°. According to the different Kinds of Matter ; thus the Sound of aPiece of Gold is much graver than that of a Piece of Silver of the fame Shape and" Dimensions 5 in which Cafe, the Tones are proportional to the Specific Gravities.

2. According to the different Quantities of the fame Mat- ter in Bodies of the fame Figure ; as a folid Sphere of Brafs, one Foot in Diameter, founds acuter than a Sphere of Brafs two* Foot Diameter 5 in which Cafe thbToneS are proportional to the Quantities of Matter.

Here, then, are different Tunes connected with different fpecific Gravities, and different Quantities of Matter 5 yet cannot the different Degrees of Tune be referr'd to thofe Quantities, t$c. as the immediate Caufe. In Effect., the Meafures of Tune are only to be fought in the Relations of the Motions that are the Caufe of Sound, which are no where fo difcernable as in the Vibrations of Chords. See Chori?.

Sounds, we know, are produe'd in Chords by their vibra- tory Motions ; not, indeed, by thofe fenfible Vibrations of the whole Chord, but by the infcnfible ones, which are in- fluenc'd by the fenfible, and, in all Probability, are propor- tional to them. — So that Sounds may be as juftly meafur'd in the latter, as they could be in the former, did they fall under our Senfes : But even the fenfible Vibrations are too fmall and quick to be immediately meafur'd. — The only Refource we have, is to find what Proportion they have with fome other Thing, which is effected by the different Tenfi- ons or Thicknefs, or Lengths of Chords, which, in all other Refpefts, excepting fome one of thofe mention'd, are the fame. See Vibration.

Now, in the general, we find that in two Chords, all Things being equal, excepting theTenfion, or the Thicknefs, or the Length, the Tones are different $ there muft therefore be a Difference in the Vibrations owing to thofe different Tenficns, &c. which Difference can only be in the Velocity of the Courfes and Recouries of the Chords, thro' the Spaces wherein they move to and again. — Now, upon examining the Proportion between that Velocity, and the Things jufi mention'd, whereon it depends, 'tis found to a Demon ftrati on, that all the Vibrations of the fame Chord are perform'd in equal Times.

Hence, as the Tone of a Sound depends on the Nature of thofe Vibrations whofe Differences we can conceive no other- wife than as having different Velocities, and as the fmall Vibrations of the fame Chord arc all perform'd in equal Time 5 and as 'tis found true in Facl, that the Sound of any Body arifing from one individual Stroke, tho* it grow gradu- ally weaker, yet continues in the fame Tone from firft to laft ; jt follows, that the Tone is neceffarily connected with a certain Quantity of Tune in making every fingle Vibration ; or that a certain Number of Vibrations, accomplifh'd in a given Time, conftitutes a certain and determinate Time 5 for the frequenter thofe Vibrations are, the more acute is the Tune 5 and the flower and fewer they arc in the fame Space of Time, by fo much the more grave is the Tune; fo that any given Note of a Tune, is made by one certain Meafure of Velocity of Vibrations, i. e. fuch a certain Number of Covirfes and Recourfes of a Chord or String in fuch a certain Space of Time, conftitutes a determinate Tune. See Note.

This Theory is ftrongly fupported by our beft and lateft Writers on Mufic, Dr. Holder, Mr. Malcolm, &c. both by Reafon and Experience. — Dr. Wallis, who owns it very rea- fonable, adds, that 'tis evident the Degrees of Acutenefs are reciprocally as the Length of the Chords 5 tho', he fays, he will not pofitively affirm that the Degrees of Acutenefs anfwer the Number of Vibrations as their only true Caufe : But his Diffidence arifes hence, that he doubts whether the Thing have been fufficiently confirm'd by Experiment, — Indeed, whether the different Number of Vibrations in a given Time is the true Caufe on the Part of the Object, of our perceiving a Difference of Tune,\s a Thing which we conceive does not come within the Reach of Experiment $ 'tis furficient the Hypothefis is reafonable. See Concord, Har- mony, $£c.

TUNICA, a kind of Waftecoat or Under-Garment wore by the Ancients, both at Rome, and in the Eaft.

The common People ordinarily wore only a fingje Tunica 5 but thofe of better Fafhion wore a Tcga or Gown over it. See Toga.

The Philofophers wore a Gow 7 n without a Tunica^ as pro- fefling to go half naked.

The Tunica was peculiar to the Men - 7 the Under-Garment of the Women not being call'd Tunica, but Stela. SceS'roLA., The Senators wore their Tunica enrich'd with feveral little Pieces of Purple, cut in Form of. large Nails 5 whence it was call'd Laticlava : The Knights had leHiT Nails on their Tu- nica, which was hence call'd Anguftklava ; The common People wore their Tunica without any Nails at all.— And 'twas by^ thefe three different Sorts of Tunicas, that the three different Orders of the Roman People werediftinguifh'd. Sc&Laticlava, f£c.

Among the Religious, the woollen Shifts, or Under-Gar- ments, are ffill call'd Tunicas or Tuniques.

Tunica, or Tunic, in Anatomy, is a Term apply'd to> the Skins or Membranes which coat or inclofc the Vcflels and divers other of the lefs folid Parts of the Body. See Memerane.

The Eye confifts principally of a Number of Ti'.nics rano'd over one another 5 as the Tunica Albuginea, the Tunica Cor- nea, thzTmiica Retiformis, &c. See Eye, &c. Tunica Vaginalis. See Vaginalis. . TUNNAGE, or Tonnage, a Duty or Cuftom due for Merchandize brought or carry 'd in Tuns,, and fuch like Veffels, from or to other Nations 5 thus call'd, becaufe rated at fo much/cr Tun. See Custom.

Tunnage is properly a Duty impos'd on Liquids according to their Meafures ; as Poundage is that impos'd on other Commodities according to their Weight. See Poundage.

They were both firft, fettled by Authority of Parliament under King Edward III 5 were re-eftablifh'd in 1660, under the Reign of King Charles II. for his Life, upon abrogating all the Laws made under Oliver Cromwell ', and re ordaining the Execution of the ancient Laws and Regulations $ and have been continu'd and renew'd by the Parliaments ever fince. — By an A£t made in the firft Year of the Reign of Queen Anne they were continu'd for 96 Years, expiring in the Year 1798.

This Duty at firft was 4/. 10 s. Sterling per Tun, for French Wines brought into the Port of London by the Fng- lift ; and only three for that brought in the other Ports. — For the fame Wine imported by Strangers to London, this Duty was 6/- r £nd that brought into the other Ports 4/. j y. Sterling.

. Rhenifh. Wine, in Virtue of the fame A£t, paid 7/. 10 s. Sterling ; and Spanip, Tortugtiefe, Malmfey } and Greek Wines, the fame as the French Wines.

But there have' been divers additional Duties added fince. — As, the additional T)uty of the old Subfidy, Seignorage Tluty of ancient Impoft of Tunnage, TJuty of additional Im- pqfi, Orphans Money, new Subfidy, &c.

Tunnage isalfo ufed for a certain Duty paid the Mari- ners by the Merchants, for unloading their Ship3 arriv'd in any Havens, after the Rate of fo much a Tun. See Duty.

TUNNEL, or Funnel, an Inftrument thro' which any Liquor is pour'd into a VeffeL — Part of the Draught of a Chimney above the Mantle-piece, is alfo call'd by the fame- Name. See Chimney.

Tunnel-A 7 "^, is a kind of Net much ufed for the catch- ing of Partridges ; thus call'd from its Form, which is a Cone 15 or 18 Feet long.

To ufe it, a Covey of thofe Birds being found, a Com- pafs is taken, and the Net pitch'd at a good Diftance from them, according to the Situation of the Ground. — Then with a natural or artificial Stalking Horfe, they are furround- ed, and gently driven towards the Net, never coming on them in a direil Line, but by Windings, Turnings, gg£ 'See Stalking.

TUNNING, a Part of the Procefs of Brewing, or rather an Operation which is the Sequel thereof. See Brewing.

The Tunning of Seer, &c. is perform'd various Ways ; fome being of Opinion 'tis beft tunned as it cools, or begins to come ; while others let it ftand longer to become riper.

The molt regular Method is to cleanfe and tun ]xx&,ss\t comes to a due Ferment, and gets a good Head j for then it has the muft Strength to clear itfelf. — What works over is to be furply'd with freOi Beer of the fame Brewing.

TURBAN, orTuRBENT, the Head-drefs of moft of the Eafiern and Mahometan Nations. See Hat, Cap &c.

A Durban confifts of two Parts, viz. a Cap, and a Shaffi of fine Linnen, or Taffaty, artfully wound in divers Plaits about the Cap.

The Turks call the Shaih Turbent s whence we have form'd the Word Turban.

The Cap is red or green, without any Brim, pretty flat, tho* roundifh a-top, and quilted with Cotton, but does not cover the Ears. — About this is wrapp'd a long Piece of

fine,