A unique symmetric gliding double screw (SGDS-) motion is constructed
which possesses a second order contact with an arbitrary given Euclide
an motion at a given position. Additionally it is shown that generally
no double screw motion exists which has this property. The constructe
d SGDS-motion can be said to be the analogue of the osculating circle
of a curve for spatial Euclidean motions. (C) 1997 Elsevier Science Lt
d.