QUA 



which being i-rdiiccd, as ftiewn above, gives the difFccence 

 of longitude. And thus is the whole triangle found. 



QuADUANT, in Gunnery, called alfo the gunntr's fquare, 

 is an initruinent ferving to elevate or point cannons, mor- 

 tars, &c. according to the places they are to be levelled or 

 direfted to. 



It confifts of two branches, made of brafs or wood ; one 

 about a foot long, eight hnes broad, and one line in thick- 

 nefs ; the other four inches long, and of the fame thicknefs 

 and breadth as the former. Between thefe branches is a 

 quadrant divided into ninety degrees, beginning from the 

 fliorter brancli, and furnilhed with a thread and plummet. 

 See its figure reprcfented in Plate I. Gunnery, fg. 5. 



The ufe of this initrnment is eafy ; nothing more being 

 required but to place the longcll branch in the mouth of the 

 cannon or mortar, and elevate or lower it, till the thread 

 cuts the degree neceii'ary to hit a propofed objeft. See 

 Pointing o/" a Gun. 



Sometimes, alfo, on one of the furfaccs of the long 

 branch, is noted the diviiion of diameters, and weights of 

 iron bullets ; as alfo the bores of pieces. See Cahber. 



Quadrant of Altitude, is an appendage of the artificial 

 globe, confiding of a lamina or flip of brafs, the length of 

 a quadrant of one of the great circles of the globe ; .ind di- 

 vided into ninety degrees. 



At the end, where the divifions terminate, there is a nut 

 rivetted on, and furnilhed with a fcrevv, by means of which 

 the inftrument is fitted on to the meridian ; and is moveable 

 round upon the rivet, to all points of the horizon. See its 

 figure in Plate XIX. AJlronomy, Jig. 9. 



Its ufe is to ferve as a fcale m meafuring of altitudes, 

 ampUtudes, azimuths, &c. See the manner of its appHca- 

 tion under the Ufe of the Globe. 



QUADRANTAL, in Antiquity, a vefiel in ufe among 

 the Romans for the meafuring of liquids. 



It was at firft called amphora ; and afterward quatlra?ital, 

 from its form, which was iquare every way, like a die. 



Its capacity was eighty librx, or pounds of water, which 

 piade forty-eight fextaries, two urnne, or eight congii. 

 QuADRANTAL Space, in Geometry. See Quaduant. 

 QuADRANTAL Triangle, is a fpherical triangle, one of 

 whofe fides at lealt is a quadrant of a circle, and one of its 

 angles a right angle. 



QUADRANTATA Terr^e, in our Ancient L&iv 

 Books, is ufed for a quarter of an adre, now called a rood; 

 which fee. 



QUADRAS Isles, in Geography, ifl.wds fituated on the 

 N.W. coalt of North America, between Pintard's found and 

 the ftraits of Fuca ; among which Hes NooTKA'syi«H</, 

 which fee. They were fo called by Capt. Ingraham, after 

 the name of a Spanifh commander of two fchooners, who 

 palled through this channel in the year 1792. 



QUADRAT, QuADRATUM, called alfo geometrical 

 fquare, and line of Jliadoius, is an additional member on the 

 face of the common Gunter's and Sutton's quadrants ; of 

 fome ufe in taking altitudes, &c. 



The quadrat more diftinftly exhibited in Plate VI. Sur- 

 veying, fg. 1 3. has each of its lldcs divided into a hundred 

 equal parts, commencing from the extremes ; fo that the 

 number 100 falls on the angle, reprefenting tangents to the 

 arc of the limb. 



The divifions are diftinguilhed by little lines from 5 to 5, 

 and by numbers from 10 to 10 ; and the divifions being 

 occafionally produced acrofs, form a kind of lattice, con- 

 fiftingof 10,000 little fquares. 



The proportion here is, as radius is to the tangent of the 

 angle of altitude at the place of obfervation {i.e. to the 



QUA 



parts of the quadrat cut by the thread), fo is the didance 

 between the llation and the foot of the objefl, to its height 

 above the eye. See Altitude. 



Ufe of the Quadrat, Geometrical Square, or Line of Shado-JJS. 

 I. The quadrant being vertically placed, and the fights 

 diredled to the top ot the tower, or other object, whofe 

 height is required ; if the thread cut the fide of the quadrat 

 marked right Jhado<ws, the dillance from the bafe of the tower 

 to the point of ftation is lefs than the tower's height. If 

 the thread falls on the diagonal of the fquare, the diflancc is 

 jull equal to the height. If it fall on that fide m.arked 

 verfdjliadoivs, the dillance exceeds the height. 



Hence, meafuring the dillance, the height is found by 

 the rule of three ; inafmuch as there are three terms given. 

 Indeed, their difpofition is not always the fame ; for when 

 the thread cuts the fide of right fliadows, the firft term in 

 the rule of three ought to be that part of the fide cut by the 

 thread ; the fecond, the fide of the fquare ; and the third, 

 the diftance meafured. If the thread cut the other fide, the 

 firft term is the whole fide of the fquare ; the fecor.d, the 

 parts of the fide cut by the thread ; and the third, the dif- 

 tance. 



For an inftance of each. Suppofe, e. gr. in looking at 

 the top of a lleeple, the thread cut the fide of right (hadowg 

 in the point 40, and that the diftance mealures 20 poles, the 

 cafe then will ftand thus : as 40 is to 100, fo is 20 to a fourth 

 term, which we find to be 50 ; the height of the fteeple in 

 poles. Again, fuppofing the thread_ to fall on the other 

 fide, in tlie point 60, and the dillance to meafure 35 poles ; 

 the terms are to be difpofed thus : as 100 is to 60, fo is 35 

 to a fourth term, I'iz. 2i,the height required. See Alti- 

 tude. 



Ufe of the Quadrat without Calculation. — The preceding 

 cafes may be formed without calculation, where the divifions 

 of the fquare are produced both ways, fo as to form the 

 area into little fquares. 



Thns, fuppofe, i. The thread to fall on 40 in the fide of 

 right fhadows, and the diftance be meafured 20 poles ; feek 

 among the little fquares for that perpendicular to the fide 

 which is 20 parts from the thread ; this perpendicular will 

 cut the fide of the fqu.are next the centre, in the point 50, 

 wiiich is the height required in poles. 



2. If the thread cuts the fide of verfed fliadows in the 

 point 60, and the diftance be 35 poles ; count 35 parts on 

 the fide of the quadrat from the centre ; count alfo the divi- 

 fions of the perpendicular from the point 35 to the thread, 

 which will be 2 1 , the height of the tower in poles. 



Note, In all cafes the height of the centre of the in- 

 ftrument is to be added. See Altitude, and Shadow. 



Quadrat, in Aflrology, called alfo Quartile, an afpecl 

 of the heavenly bodies, in which they are dillant from each 

 other a quadrant, or ninety degrees. See Aspect. 



Quadrat, m Printing, is a fort of fpacc ; that is, a piece 

 of metal, call like the letters, to be ufed occafionally in 

 compofing, in order to form the intervals between words, at 

 the end of hnes, &c. See Printing. 



There are quadrats of divers fizes, as m quadrats, n 

 quadrats, &c. which are refpedlively of the dimenlions of 

 fuch letters. 



QUADRATA, in Ancient Geography, a town of Higher 

 Pannonia, placed on the banks of the Save by Antonine's 

 Itinerary. 



Qual^iata, in Geography, a town of Naples, in the 

 province of Bari ; five miles N.W. of Ruvo. 



Quadrata is the Itahan term in canto fcrnio for Gre- 

 gorian or fquare black notes. 



U 2 Quadrata 



