Some axioms concerning ocular rotations / G.C. Savage.

G. C. Savage

Date:: 1906

Credit: Some axioms concerning ocular rotations / G.C. Savage. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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ROTATION'S.* G. C. SAVAGE, M.D. NASHVILLE. TENX. A convex sphere set in a concave hemisphere, the two having a common center, the one fitting in the other as shown in Figure 1, can be rotated on any one of its diameters, and only on a diameter, as an axis. The center of curvature, the point to which all the radii con- verge, is the center of rotation. The point on the sur- face at which the force is applied determines what the plane of rotation shall be and fixes the axis of rotation at right angles to this plane. This can be best under- stood by a study of Figure 1. A B D represents the concave hemisphere whose cen- ter is c; a d b e represents the convex sphere whose cen- ter is also c. If the force is so applied that a b shall be the rotation plane, the axis of rotation will be the diam- eter d e; if the force makes d e the rotation plane, then the diameter a b becomes the axis of rotation. In like manner, if the force makes m n the rotation plane, the diameter h i becomes the axis of rotation; and if the force makes li i the rotation plane, then the diameter m n becomes the axis of rotation. The law governing the rotation of a convex sphere lying loose in a concave hemisphere, the two being concentric, is that the force may be so applied as to make the plane of rotation any * This paper has been accepted by the executive committee of the Section on Ophthalmology of the American Medical Association, to be presented before the Section at the Boston Session, June 5-8. 1000, and to be published in The Jouhxal A. SI. A. later

Some axioms concerning ocular rotations / G.C. Savage.

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