CHAP. XXX.
The Shape and Mass of the Iron are of most
importance in coition.
bservation has shown above that the shape
and mass of the loadstone have great influence in magnetick coitions; likewise also the shape and mass of the iron bodies
give back more powerful and steady forces. Oblong iron rods are both drawn more quickly to a loadstone and cleave to it
with greater obstinacy than round or square pieces, for the same reasons which we have proven in the case of the
loadstone. But, moreover, this is also worthy of observation, that a smaller piece of iron, to which is hung a weight of
another material, so that it is altogether in weight equal to another large whole piece of iron of a right weight
* (as regards the strength of the
loadstone), is not lifted by the loadstone as the larger piece of iron would be. For a smaller piece of iron does not
join with a loadstone so firmly, because it sends back less strength, and only that which is magnetick conceives
strength; the foreign material hung on cannot acquire magnetick forces.