On the Touching of pieces of Iron
_of divers shapes._
Bars of iron, when touched by a loadstone, have one end north, the other
south, and in the middle is the limit of verticity, like the æquinoctial
circle on the globe of a terrella or on an iron globe. But when an iron
ring is rubbed on one side on a * loadstone, then the one pole is on the
place that was in contact, whilst the other is at the opposite point; and
the magnetick power divides the ring into two parts by a natural
distinction which, though not in shape, yet in power and effect is like an
æquator. But if a thin straight rod be bent into a ring without any welding
or union of the ends, and be touched in the middle by a loadstone, both
ends will be of the same verticity. Let a ring be taken which is whole and
continuous, and which has been * touched by a loadstone at one place, and
let it be divided afterward {130} at the opposite point and straightened
out, both ends will also be * of the same verticity, no otherwise than a
thin rod touched in the middle or a ring not cohærent at the joint.
* * * * *