raction be divided into the same number
of parts, the like named parts of the weight will correspond to the
intermediate parts of the radius.

The orbe of virtue extends more widely than the orbe of motion of any
magnetick; for the magnetick is affected at its extremity, even if it is
not moved with local motion, which effect is produced {104} by the
loadstone being brought nearer. A small versorium also is turned when a
good distance off, even if at the same distance it would not flow towards
the loadstone, though free and disengaged from impediment.

The swiftness of the motion of a magnetick body to a loadstone is dependent
on either the power of the loadstone, on its mass, on its shape, on the
medium, or on its distance within the magnetick orbe.

A magnetick moves more quickly towards a more powerful * stone than towards
a sluggish one in proportion to the strength, and [as appears] by a
comparison of the loadstones together. A lesser mass of iron also is
carried more quickly towards a loadstone, just as also one that is a little
longer in shape. The swiftness of magnetick motion towards a loadstone is
changed by reason of the medium; for bodies are moved more quickly in air
than in water, and in clear air than in air that is thick and cloudy.

By reason of the distance, the motion is quicker in the case of bodies near
together than when they are far off. At the limits of the orbe of virtue of
a terrella a magnetick is moved feebly and slowly. At very short distances
close to the terrella the moving impetus is greatest.

A loadstone which in the outmost part of its orbe of virtue * hardly moves
a versorium when one foot removed from it, doth, if a long piece of iron is
joined to it, attract and repel the versorium more strongly with its
opposite poles when even three feet distant. The result is the same whether
the loadstone is armed or unarmed. Let the iron be a suitable piece of the
thickness of the little finger.

For the vigour of the loadstone excites verticity in the iron and proceeds
in the iron and through the iron much further than it extends through the
air.

The vigour proceeds even through several pieces of iron (joined * to one
another end to end), not so regularly, however, as through one continuous
solid.

Dust of steel placed upon paper rises up when a loadstone is moved near
above it in a sort of steely hairiness; but if the loadstone is placed
below, such a hairiness is likewise raised.