Where the indirect method is employed in skioscopy, best results are secured through the use of the Woolf ophthalmic bracket and concentrated filament lamp, together with an iris diaphragm chimney. The latter permits the reduction or increase of the amount of light entering the eye, as it is agreed that a large pupil requires _less_ light, a small pupil requiring _more_ light. The bracket referred to permits the operator to swing the light into any desired position (Fig. 9), while the iris diaphragm chimney serves as a shutter. This apparatus may also be employed for muscle testing, as described in a subsequent paragraph. A SIMPLIFIED SKIOSCOPIC METHOD In using the Ski-optometer, instead of working forty inches away from the patient in skioscopy and deducting 1.D., the refractionist will find it more convenient to work at a twenty inch distance, deducting 2.D. This working distance may be accurately measured and maintained by using the reading rod accompanying the instrument. Instead of deducting 2.D. from the total findings, however, it is preferable to insert a +2.D. trial-case lens in the rear cell of the instrument directly next to the patient’s eye. After determining the weakest lens required to neutralize the shadow in both meridians, the additional +2.D. lens should be removed and the total result of the examination read from the instrument’s register. To illustrate a case in skioscopy where spherical lenses are employed to correct both meridians, assume that the vertical shadow requires a +1.25D lens to cause its reversal, while the horizontal requires +2.00D. Employment of the customary diagram, illustrated in Fig. 10, would show the patient required +1.25 sph. = +.75 cyl. axis 90°, which when transposed is equivalent to +2.00 sph. = -.75 cyl. axis 180°. [Illustration: Fig. 10—Where spherical lenses are employed in skioscopy, above indicates patient requires] +1.25 Sph. = +.75 Cyl. Axis 90° or +2 Sph. = -.75 Cyl. Axis 180° It should be noted that the total spherical power is +2.00D, as the Ski-optometer’s register shows, while the difference between the two meridians is 75, which is the required strength of the cylinder. By then turning the cylinder reel to .75, and setting the axis indicator at 180° (because by using minus cylinders, the axis must be reversed) the patient should read the test-type with ease if the skioscopic findings are correct. Thus with the Ski-optometer, it is not even necessary to learn transposition, since the instrument automatically accomplishes the work, avoiding all possibility of error. EMPLOYING SPHERES AND CYLINDERS IN SKIOSCOPY Another commonly used objective method may be employed with even greater facility through the combined use of both the Ski-optometer’s spherical and cylindrical lenses. As previously suggested, insert the +2.00 spherical trial-case lens in the rear of the instrument, working at a twenty inch distance, then proceed to correct the strongest meridian first.