in the warping harness will change and this in turn will change the amount of warp in the mirror. This means that with this method of mounting the mirror each time the telescope is pointed in a new direction, a small adjustment of the warping harness may be required. In small telescopes where the weight of the mirror is small, this method of mounting may not produce changes in the tension of the warping harness large enough to necessitate readjustment each time the telescope is moved, and so, may be quite acceptable. In larger instruments (eight inches aperture and up) this method of mounting the mirror may be found to be objectionable because of the necessity of making frequent adjustments of the warping harness.
The warping harness and mirror-mount shown in Figures 3a and 3b grips the mirror firmly at three points around its edge. This carries the weight of the mirror and provides positive collimation no matter what direction the telescope is pointed. The x-member of the warping harness is held in position by a thin, flexible sheet metal spider which maintains it in the proper position relative to the mirror, but does not otherwise restrain its movement. Counterweights balance the weight of the warping harness in all positions of the telescope so that only the flexure forces produced by the x-member are exerted against the mirror. All gravitational forces on the warping harness are taken care of by the sheet-metal spider and the counterweights. Thus the net warping forces exerted on the mirror remain constant no matter in what direction the telescope points. It is felt that with this design of mirror-mount and warping harness, Yolo reflectors in sizes up to 30- or 36-inch aperture can be made to operate successfully.