W. Blaschke [1] (1) has made a survey of the differential geometry of the ruled surfaces corresponding to the dual vector A(Z) = a(t) s a0(t) which is a function of the real parameter t. Using the resemblance of the Blaschke and Frenet formulae L. Biran [2] has made a study of the ruled surfaces similar to the theory of the space curves. In this paper,