T r R 



T 1 R 



dite^ivc of beautiful pafl'.igcs, mack- the molt of by a com- 

 pofer ; it is liicn faid to be ben Itnilo. 



TIRBl A, in Geography, a town of Spain, in Catalonia ; 

 l6 miles N.VV. of Urgel." 



TIRE, or, as the feamcn pronounce it, tier of guns. 

 See TiKii. 



TIREBOLI, in Geography, a river of Turkiai Aimc- 

 nia, which runs into the Black fea at Tireboli. — AUo, a 

 town of Tiirkilh Armenia, on the Black fea, at the mouth 

 of a river of the fame name ; 20 miles N.E. of Kei-efour. 



TIREH, a town of Afiatic Tmkey, in Natolia, lituated 

 on tile Meinder ; the inhabitants are chiefly Turks: 32 

 miles S.S.E. of Smyrna. N. lat. 38° 8'. E. long, zf 40'. 



TIRES of lyheels, in Rural Economy, the ilr.ips, flips, 

 bands, or hoops of iron which are put round them for the 

 purpofe of guarding and protecting them againft the effetts 

 of the roads, as well as fecuring and keeping them tight in 

 their different parts. The molt advantageous and beneficial 

 form of tire for wheels of different kinds and breadths in 

 different points of view, have probably not yet been well al- 

 certaincd. It is obvious, however, that it (hould be fuch 

 as may have the lead poflible tendency to penetrate and 

 deltroy the furfaces on which tiie wheels aft and move. It 

 woidd appear, that almolt all of thofe who have written on 

 this fubjeft, have gone upon a wrong or falfe principle ; 

 nearly all having directed that the exterior furface, 

 wlien more bands than one are ufed, as in the cafe of 

 broad-whcelcd waggons, fiiould be unequal ; in fuch a man- 

 ner as that tlie centre band may receive the whole of the 

 preffure, when the road is even and compofed of hard ma- 

 terials ; the other bands being only in readinefs to fuitain 

 their portions of the burthen, when, either from unevennefs 

 or the want of firmnefs in it, they may be brought into 

 contadt with it. 



It is well known, however, to every one, that it is the 

 nature of a wedge to work its way, when forcibly applied 

 to a cleft or opening ; and that the extent of its penetration 

 will depend on the fliarpnefs or acutenefs of its wedge- 

 form, and the power by which it is impelled. Admitting 

 this to be the faCt, it is plain that every wheel, the tire of 

 which afts in the fmalleit degree as a wedge, muft enter a 

 loofe foil, furface, or road, more or lefs, in proportion as 

 its edge or projection is more or lefs acute and protruding, 

 or the contrary. 



A roUing cylinder is not eafily capable of penetrating 

 below the furface, for tliis reafon, that it prefents no one 

 protruding point ; but where a rolling body fw-ells out in a 

 projefting manner in the middle, it will unqueftionably aft 

 or work deeper in that part where it is the moil promi- 

 nent, than in any other, as it is a fort of obtufe wedge. 

 And fuch muft be the cafe in every wheel of which the 

 tire is not cylindrical ; as when its protruding part gets 

 in, the whole body foon finds its way. 



A broad flat tire is not, however, without its inconve- 

 nience ; as, whether the road be good or bad, it prefents 

 the fame furface, and, of courfe, is as much refifted in its 

 front, while on a hard furface, as while on one into which it 

 finks. Confequently, the cylindrical tire can never draw 

 light and free, though it will not by any means penetrate 

 deeply into any tolerably found furface. 



Flat tires are probably, however, the befl of any for 

 narrow wheels. 



In confequence of the above, it has been propofed by 

 fomc, that every wheel fhould be furnifhed with a conca-ve 

 or hollow tire which is cylindrical ; but, that after leaving 

 two rims, of proportionate breadth, at the edges, the whole 



intermediate fpace (hould be fcooped out, or otherwife hol- 

 lowed. By this means, on hard roads, the wheel would 

 ride on the two rims only : while on foft roads, the whole 

 would bear up the burthen. All fuch wheels, the tires 

 of which have even the fmalleft tendency to a wedge-hke 

 form, invariably, it is faid, throw the foil or earth from 

 tiiem ; fquee/.ing it out at the fides, and burying them- 

 felves, not only in the furrows they make, but under the 

 very mud which they force from out of them : while, on 

 the contrary, the concave tire, it is fuppofed, keeps in the 

 fott foil, unlefs, indeed, it be in an abfolutely floppy Hate, 

 and forces it, by compreihon, to bear up tlie weight or 

 burthen. It is obferved, that let two wheels be tried on 

 a meadow which is not very firm in its furface, the cylin- 

 drical tired wheel will, an"uredly, aft better than that with 

 a receding or convex edged fort of tire ; but that the con- 

 cave tired wheel could not, it is believed, fail to difplay 

 its fuperiority in feveral of the molt defirable points and 

 refpefts. 



Let it be fuppofed that the tire of a waggon-wheel is 

 nine inches in breadth, and cylindrical : at the two edges 

 leave a band of one inch in breadth, or more ; then groove 

 out the intermediate fpace, to an inch and a half in depth 

 iu the centre, rounding it in gradually. Such a tired 

 wheel would, it is faid, on a hard road, prefent only two 

 inches of bearing ; while the refiilance would gradually in- 

 creafe in proportion as the incumbent weight, and the 

 foftnefs of the furface over which it may be proceeding, 

 fliould bring the whole to bear in an equal manner. The 

 foft foil could not elcape fo calily, at leaft, it is conceived, 

 from under a concave tire, as thofe of the oppofite kind, 

 confequently it could not add to the exterior impediments 

 of wheels. 



It mult neverthelefs be admitted, it is faid, that the con- 

 cav" tire is liable to fome diladvantage ; for inftance, it will 

 at times clog, and, poffibly, not only choke its own groove, 

 but even accumulate confiderably more ; which will adhere 

 to the clay and other matters with which the groove may 

 be filled. In this way, it would, iu faft, it is thought, be- 

 come, iu a certain meafure, cylindrical. But that if it did 

 no more than fill its groove on heavy foils, it would not 

 prove fo highly objeftionable ; for, on fuch, the whole 

 breadth of the tire ought to prefs the foil or furface. 



The remedy fuggelled for the above inconvenience, in 

 fuch cafes, is that of a fuitable fixed fcraper, which has no 

 difficulty in it, at leaft, for carriages on one pair of wheels, 

 or for the hind wheels of waggons. Such a fcraper, and 

 the mode of fixing it in fuch cafes, may be feen defcribed in 

 fpeaking of fcrapers for different kinds of implements, 

 tools, &;c. 



Thefe hints and fuggeitions may be ufeful in leading to 

 farther improvements on the tires of wheels, which is a 

 matter of great importance in different points of view, and 

 which, as has been feen, has yet been thought but little 

 upon in a proper manner. See Wheel. 



TIREYMEG Lake, in Geography, a lake of North 

 America. N. lat. 61° 52'. W. long. 107°. 



TIRGUBIS, or TiGUBl, in Ancient Geography, a town 

 of Afia, in Mefopotamia, on the banks of the river Cha- 

 boras, according to the Thcodofian table and Ptolemy ; 

 fituated N.W. of Refaina. 



TIRGUL, in Geography, a town of European Turkeyj 

 in Moldavia ; 62 miles W. of Jaffy. 



TIRGULFORMOSA, a town of European Turkey, 

 in Moldavia ; 20 miles W. of Jaffy. 



TIRING. 



