. Encyclopaedia; or, A dictionary of arts, sciences, and miscellaneous literature; constructed on a plan, by which the different sciences and arts are digested into the form of distinct treatises of . an 45, but lefsthan 56° 20, flip the notch on the tangent fide of theturned cheek to the degree o in the tangent line onthe fide of the compafs ; the radius taken between thepoints fartheft from the curfor; the difference betweenthe aperture of ihe other and thefe, added together,will be the tangent required. Thus, for the tangentsof other degrees under 71. After the like mannermay the
. Encyclopaedia; or, A dictionary of arts, sciences, and miscellaneous literature; constructed on a plan, by which the different sciences and arts are digested into the form of distinct treatises of . an 45, but lefsthan 56° 20, flip the notch on the tangent fide of theturned cheek to the degree o in the tangent line onthe fide of the compafs ; the radius taken between thepoints fartheft from the curfor; the difference betweenthe aperture of ihe other and thefe, added together,will be the tangent required. Thus, for the tangentsof other degrees under 71. After the like mannermay the fecant of any number of degrees under 71 befound. Mr Heath, a mathematical inftrnment-maker inLondon, conflrufted a parr of proportions! compafTes,in 1746, with a curious and ufcful contrivance for pre-venting the fliortcr legs from changing their pofition,when thefe compaffcs were ufcd. It confiftcd of afmall beam foldered toa fcrew, and running parallel tothe leg of the compalfes, nearly of the length of thegroove ; in this beam a flit was made, which admittedof a fliding-nut, the other end of which fell into a holeill the bottom of the fcrcw, belonging to the great nut of r 0 T N [ N c; Plate ~,lilh
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Keywords: ., bookcentury1700, bookdecade1790, booksubjectencyclo, bookyear1798
