The Ether of Space

by Sir Oliver Lodge

At the earth's distance, which is nearly 200 solar radii, solar gravity will be reduced in the ratio of 1:200 squared.

Hence the force exerted by the sun on the earth is

25 × 6 × 10²¹ / (200)² tons weight.

That is to say, it is approximately equal to the weight of 37 × 10¹⁷ ordinary tons upon the earth's surface.

Now steel may readily be found which can stand a load of 37 tons to every square inch of cross-section. The cross-section of a bar of such steel, competent to transmit the sun's pull to the earth, would therefore have to be

10¹⁷ square inches,
or say 700 × 10¹² square feet.

And this is equivalent to a million million round rods or pillars each 30 feet in diameter.

Hence the statement in the text (page 26) is well within the mark.

The Pull of the Earth on the Sun.

The pull of the earth on the sun is, of course, equal and opposite to the pull of the sun on the earth, which has just been calculated; but it furnishes another mode of arriving at the result, and may be regarded as involving simpler data—i.e. data more generally known. All we need say is the following:—