202 WEBER'S LECTURES Es steht d. Richtung d. Kraft i zu r & zu ds. Also ax + bß + cy = 0 ferner folglich, a! a + b'ß + c'y = 0 a2 + ß2 + y2 = 1 be' - cb' a yf{bc' - cb')2 + (ca' - ac')2 + (ab' - ba') ß = ca - ac V cos p = aa' + bb' + cd sin p = yJ(a2 + b2 + c2)(a'2 + b'2 + c'2) - (aa' + bb' + cc')2 = yj(ab' - ba')2 + (bd - cb')2 + (ca' - ac')2. Folglich[186] Jv , . i ds m , dX = + j- (be - cb) y = ab' - ba' Jv idsm dY = + ) 2- (ca ~ ac) dZ = + - l-^(ab'-ba'. 2 [186] In the following three equations, initial minus signs have been changed to plus signs and then minus signs inserted above them all the changes are made in pencil.