A HOLE THROUGH THE EARTH.

New Zealand Herald, Volume XXV, Issue 9022, 7 April 1888, Page 2 (Supplement)

A HOLE THROUGH THE EARTH.

To a query in the English Mechanic as to the effect of gravity on a body dropped into a hole right through the earth, the following answers were returned :— " If a hole could be made right through the earth, and a cannon ball dropped in it, then the ball would ' fall , far past the centre of earth till its inertia was overcome by gravity. It would then comeback past the centre again, only not so far, and back again, until it finally came to rest at centre; the ball would, in fact, act much the same as a pendulum set in motion." " The cannon ball would pass the centre of the earth, and suppose there was no friction from the air in the shaft, it would go as far beyond the centre as the point from which it started (that is, supposing it was not melted on the way by the great heat of the earth's centre). It would then return to the point it started from, and continue to traverse the shaft from end to end. Air in the shaft would have the effect of bringing the ball to rest at a point in the shaft nearest the centre of gravity of the earth." " ' Principa' having sunk his little shaft, and rendered it fire, water, and gas-tight, and having pumped all the air out of it, may say good-bye to his English friends, and without jerk or jolt land on the New Zealand surface in about a minute past the half-hour from starting. As ' Principia' will not be able to hold his breath quite so long as that, it will be necessary for him before starting to go and put his head in a bag of air. On reaching the half-way point, 3956 miles from start, he will certainly find it quite put of the question to ' stop' for refreshments, as his velocity at that moment will be at the rate of not less than 11$ miles per second, or 40,765 miles per hour! Bub ' Principia' need not be frightened about impact against the New Zealand end of his subway, for he will 'slow up' beautifully by the automatic brake which gravity imposen on momentum, and will arrive very gently at his journey's end. 'All's well that ends well !' ' Principia , need not remain in New Zealand; ne can return thence to England at the same rate as he camo. In fact, any evening after tea he could drop through to New Zealand, have a chat with his friends there, and return to the old folk at home in time for supper."