This many-named and enigmatical tribe was of considerable importance in the history of India and Persia in the 5th and 6th centuries, and was known to the Byzantine writers, who call them 'E40aXiroL, Ei)Owytroi, NecbOaAtroc or 'A(3b€Xoi.
Then the deviation y= DE of the neutral axis of the bent beam at any point D from the axis OX is given by the relation d 2 y Ml dx 2 = EI' where M is the bending moment and I the amount of inertia of the beam at D, and E is the coefficient of elasticity.
Associated with these new units there is a system of extensive quantities of the second species, represented by symbols of the type = Ei 121 [i=I, 2,...zn(n - I)].
Then the deflection at the centre is the value of y for x = a, and is _ 5 wa4 S - 14 EI' The radius of curvature of the beam at D is given by the relation R=EI/M.
