Although one significant method of interpolation is that of the cubic spline, it has the drawback of occasionally producing undesired inflections in a curve. As a remedy, the spline can mathematically be "stretched" (so to speak) in much the same way that a draftsman's spline could be pulled at its ends while still being anchored at certain points throughout.This thesis will make use of FORTRAN subroutines given in the April, 1974 issue of Communications of the ACM, which have the capability of applying this tension factor to a cublic spline in a graphics package. It will also discuss the necessary modifications which are required before compatibility can be achieved between these subroutines and the Tektronix terminal which is coupled to the DEC-10 here at Ball State University.