Practical engineering drawing and third angle projection, for students in scientific, technical and manual training schools and for ..draughtsmen .. . semicircle the square of an ordinateequals the product of the segments into which it divides the diameter. In Fig. 122 take F^ andF^ as the foci, erect a peri^endicular F^ S to the axisFi F^ and on it lay off F^ R equal to the constant F^ F, at 0 and draw a semicircle of radius 0 cuts the axis at A and B, the extreme points ofthe curve; for k = F^ A X F-^ B. Any other point be obtained by drawing from F^ a circular arc ofr
Practical engineering drawing and third angle projection, for students in scientific, technical and manual training schools and for ..draughtsmen .. . semicircle the square of an ordinateequals the product of the segments into which it divides the diameter. In Fig. 122 take F^ andF^ as the foci, erect a peri^endicular F^ S to the axisFi F^ and on it lay off F^ R equal to the constant F^ F, at 0 and draw a semicircle of radius 0 cuts the axis at A and B, the extreme points ofthe curve; for k = F^ A X F-^ B. Any other point be obtained by drawing from F^ a circular arc ofradius F^ t greater than F^ A; draw t R, then R x perpen-dicular to it; X F^ will then be the p and F^t the p forfour jooints of the curve, which wdll be at the intersection ofarcs struck from F^ and F.^ as centres and with those radii. To get a normal at any point T draw 0 T, then make angle F^ T s = 6 — F^ TO; Ts will bethe desired THE CATENARY. 214. If a flexible chain, cable or string, of uniform weight per unit of length, be freelysuspended by its extremities, the curve which it takes under the action of gravity is called aCatenary, fi-om catena, a chain. A simple and practical method of obtaining a catenary on the drawing-board would be to inserttwo pins in the board, in the desired relative position of the points of suspension, and then attachto them a string . of the desired length. By holding the board vertically the string would assumethe catenary, whose points could then be located with the pencil and joined in the usual mannerwith the irregular curve. Otherwise, if its points are to be located by means of an equation, wetake axes in the plane of the curve, the i/-axis (Fig. 123) being a vertical line through the lowestpoint T of the catenary, while the x-axis is a horizontal line at the distance m below T. Thequantity m is called the parameter of the curve and is equal to the length of string which rep
Size: 2099px × 1191px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjec, booksubjectlettering
