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The line of the orbit would not then be a closed one but in the

course of time it would fill up an annular part of the orbital

plane, viz. between the circle of least and the circle of

greatest distance of the planet from the sun.

According also to the general theory of relativity, which differs

of course from the theory of Newton, a small variation from the

Newton-Kepler motion of a planet in its orbit should take place,

and in such away, that the angle described by the radius

sun-planet between one perhelion and the next should exceed that

corresponding to one complete revolution by an amount given by

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