Abstract: An adjustable base for mounting viewing, measuring, or testing instruments thereon, whereby the instrument can be positioned so that its face can be properly viewed at an available line-of-sight regardless of the orientation of the instrument case. The adjustable base consists of an upper part and a lower part defining an oblique plane therebetween wherein the upper part is rotatable relative to the lower part about an axis perpendicular to the oblique plane such that a vertical projection through the center of gravity of the instrument remains within the area of the lower base part. The instrument case is rotatable relative to the upper base part for additional adjustment depending upon the direction of the observer's line-of-sight.