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actual weight of the whole earth is. The solution depends on the gravitation of matter.

Every child is familiar with gravitation from the time it begins to walk, but the profoundest philosopher knows nothing of its cause, and science has not discovered anything respecting it except a few general facts. The widest and most general of these facts, which may be said to include the whole subject, is Sir Isaac Newton's theory of gravitation. According to this theory, the mysterious force by which all bodies on the surface of the earth tend to fall toward its centre does not reside merely in the centre of the earth, but is due to an attraction exerted by every particle of matter composing our globe. Whether this was the case was at first an open question. Even so great a philosopher and physicist as Huyghens believed that the power resided in the earth's centre, and not in every particle, as Newton supposed. But the latter extended his theory yet farther by showing that every particle of matter in the universe, so far as we have yet ascertained, attracts every other particle with a force that diminishes as the square of the distance increases. This means that at twice the distance the attraction will be divided by four; at three times by nine; at four times by sixteen, and so on.

Granting this, it follows that all objects around us have their own gravitating power, and the question arises: Can we show this power by experiment, and measure its amount? The mathematical theory shows that globes should attract small bodies at their surfaces with a force proportioned to their diameter. A globe two