who treat of the load-stone, and he will find, that all the modern ones make some remarks upon that particular. XXXVIII. This magnetic property of the terraqueous globe being admitted, it may be inferred from it, that excepting the exterior crust of the earth, which is composed of such heterogeneous parts, as are necessary for the growth and increase of the various productions and mixtures with which it abounds, all the rest, is nothing else, but a solid quarry of load-stone; and this is the opinion that is strenuously maintained by some; although there are others, who think that the magnetic virtue, is distributed through all the parts of the terraqueous globe. XXXIX. Both these opinions may be right, for they do not seem incompatible one with another; but in favour of the second, which is that which conduces best to support my sentiment, we may urge another celebrated piece of experience, which evinces efficaciously, that this very exterior earth which we touch and stand on, is impregnated with many insensible particles of load-stone or iron; and this is manifest, from the earth itself being endued with this magnetic virtue, or inclination of pointing to the pole; for bricks that are made from it, and are well burned and purged or freed from all foreign humour or moisture, and especially if they are made long and narrow, by being touched with a load-stone will acquire the virtue of pointing to the poles; and they will even acquire it without being touched, if they are laid in a north and south position, and suffered to continue so for many years together. (See Father Dechales, lib. 1 & 2, de Magnete.) It being then certain, that this quality of pointing to the pole, is peculiar to the load-stone, or the iron, and incommunicable to all other substances, it must evidently be inferred from this property in the bricks, that the very earth we touch and stand upon, is impregnated with particles of load-stone or iron. All vegetables then receiving their nourishment from the earth, it is not wonderful that there should be found in them all, some of these particles.