Mechanical exercises, or, The elements and practice of carpentry, joinery, bricklaying, masonry, slating, plastering, painting, smithing, and turning . encil pass-ing through a hole. The machine is thus pre-pared: set the first pin from the pencil to theheight, and the second from the pencil to halfthe length, then put the pins in the groves, whichbeing fixed upon the axis, move the point Bround from A to B, and describe the curveA B C D, it will be the true ellipse required. Prob. VI, Any three straight lines heinggivenioJind a fourth proportional. Pl. 6. Fig. 1. Let C A, A E be any two strai
Mechanical exercises, or, The elements and practice of carpentry, joinery, bricklaying, masonry, slating, plastering, painting, smithing, and turning . encil pass-ing through a hole. The machine is thus pre-pared: set the first pin from the pencil to theheight, and the second from the pencil to halfthe length, then put the pins in the groves, whichbeing fixed upon the axis, move the point Bround from A to B, and describe the curveA B C D, it will be the true ellipse required. Prob. VI, Any three straight lines heinggivenioJind a fourth proportional. Pl. 6. Fig. 1. Let C A, A E be any two straight lines form-ing an angle. Make A B equal to the first ofthe given lines, A C equal to the second, A Dequal to the third. Join B D, and draw C Eparallel to B D, cutting A E produced at will A E, be a fourth proportional to A B,AC, AD, or AB, AC, A D, A E. Prob. vii. To divide a line in the same propor-tion as another is divided. Pl. 6. Fig. A E be the given line, divided into theparts AB, BC, CD, DE and A 1, the line tobe divided, forming any angle with A B. JoinE I, and draw B F, C G and D H, parallel to EI, -( \ 0 ^ O JO P \\\ \\\ \^ 1 -itt-TJi • inil 11 n c t> S 7 ff S 4- -3 21 o 2 9 t M ZrnJor- JhiFrsAeJMriti Wjen3,..7:rm-7e--//{,ahir<nc^ PRACTICAL GEOMETRY. ^20 E I, cutting A1 at F G H, (hen the parts A F,F G, G H, HI, will be to one another, or to thewhole line A I, as the parts A B, B C, C D,D E, are to one another, or to the wliole lineAE. Prob. VIII. Ani/ distance leing given in feet andinches, of a part of one drawingy to divide agiven length of a similar part of another draw-ing into feet and inches j so as to form a propor-tional Fl. 6. Fig. A B represent 57 feet 2 inches, thelength of one drawing, the part between 40 andA being 7 feet 2 inches, then the distance be-tween 40 and B will contain 50 feet; and letC B be the length of another drawing, either of2:reater or less extent than the former, it
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Keywords: ., bookcentury1800, books, booksubjectcarpentry, booksubjectgeometry
