Of the gathering of Wheels. 243

i 4 wheels would cut that line at right || angles, at the lines ht and mu. But | Æ| when the centre of the out heads are F° placed in o and o, the faces of the E wheels will cut the lines eo and fo at right angles, and therefore the angle o WM en and hik are equal; ſo alſo the | angles ſit and ui v are equal, ando fr Pe| and Ilim are equal Therefore, as N ih, the half height of the wheel, is to F-| hk, a fourth of the gather,(that îs a Laun fourth of the difference between hl and Æh, ſv) ſo is en, the length of the arm, to cal| n 0, the diſtance ſought, and ſo of the Je other end, becauſe il: 1m::fr:ro. 2{5| Ws? Ñ M XI. 0f e