De Magnetica [...] Plantarum p. 637

stipiti oblongo infixæ perfectè æquilibrentur; {Actus metalloscopa.} quo facto si vim mo-
tricem experiri volueris locum venæ amicæ, cum dicto instrumento
accedes, & siquidem motrice vi fuerint imbutæ, pars illa stolonis sym-
pathica necessariò ad metallum se inclinabit; sin, certò tibi persuadeas,
supra memoratam inclinationem virgularum diuinarum esse ficti-
tiam, cum manibus metallicorum variè eam pro libitu inclinantibus
potiùs, quàm propriæ virtuti inclinatiuæ huiusmodi effectus adscri-
bendus sit: si verò eam inclinare inueneris, non ea Magnetismo, sed
elementari virtuti imputes velim, vt paulò post dicam. {Virga alnina ad aquam latentem inclinatur.} Hac arte ego
virgulam ex Alno præparatam, egregiè latentem aquam inclinatione
sua demonstrare reperi: hac quoque arte rerum diuersarum motiones
occultas indagare solertem philosophum posse, manifestum est,
vnde hic eam adiungendam existimaui, vt curiosis ingenijs, multa
experiundi occasionem præberem; Porrò vim eam, qua ad latentem
aquam, aut metallum se inclinat virga, seù versorium, verè Magne-
ticum esse non puto. Sed hanc inclinationem si quandoque contin-
gat, ea ratione, quæ sequitur, fieri verisimile est. Vapor aut exhalatio
metallica per radices arboris hausta, ramorum foliorumque humori
coniuncta constringitur, cum autem omnis vapor constrictus solu-
tusque grauiter, fit vt continuo argumento vaporis metallici, præ-
gravatum lignum incuruatumque se veluti inclinet; {Virga alnina ad aquas se inclinat & cur.} hac ratione vir-
gam alninam ad latentes aquas scrutandas præparatam, dum vapo-
rem exeuntem è terra auidè imbibit, tandem eo prægrauatum incli-
are inueni: {Experimenta.} cuius rei argumentum id sat præbuit, quod non quouis
tempore, sed ante meridiem, vt plurimum, dum vapor est copiosior,
hunc effectum præstet, meridiano vtpotè vapore consumpto non
item; tunc enim virgulam alninam paulò ante inclinatam: in æqui-
librio consistentem reperies. Quod libra quoque experieris si enim
bilancis vacuæ æquiponderantis, vnam partem ollæ aqua calida re-
fertæ, altera extra vaporem consistente, imponas, notabiliter lan-
cem ollæ impositam rorido vapore infectam, alteri præponderare
cognosces: consumpto verò vapore, aut exsiccato ad æqualitatem
redigi: Hinc quædam herbæ super mineras crescentes dicuntur gla-
ciare Mercurium; Ad Danubium Vitis clauiculi & folia plerumque
inaurata spectantur, latentis venæ aureæ signum; Crocum in sulphu-
ræis montibus crescens, eius vi imbutus stamnum aureo colore tingit.
Ex quo patet omnibus arboribus plantisque hoc proprium esse, quamuis
vapor metallicus aquæ commixtus hunc effectum notabilius præ-
stet. Hinc patet quoque cur subindè inter cortices arborum copiosus

Llll 3 /Mercu-

to a longish upright, let them balance perfectly; then, if you want to test the motive force, go with the above instrument to the site of a friendly vein and, if it is indeed imbued with a motive force, the sympathetic part of the shoot will of necessity tilt toward the metal; if not, you may be definitely assured that the above-mentioned inclination of divine rods is fictitious, since such an effect should be attributed rather to the hands of the metal prospectors tilting it variably at will than to its own inclinatory virtue: but if you find that it really does tilt, I would have you impute that not to magnetism, but to an elemental property, as I shall say later. I have found that a rod of alder prepared by this technique outstandingly revealed hidden water by its inclination, and with this technique it is obvious that a skilled philosopher could investigate the hidden movements of different things, whence I have seen fit to attach it here to offer to enquiring minds an opportunity for trying out many things. To proceed, I do not think that the force by which the rod, or spinner, inclines toward hidden water or metal is really something magnetic; but this inclination, if it ever happens, is most likely brought about in the following way. The vapour or metallic exhalation taken in by the roots of the tree is bound up in conjunction with the sap of the branches and leaves, but when all the vapour has been bound up and weightily dissolved it happens that, under the constant influence of the metallic vapour, the wood, being weighed down and bent round, seems to tilt. This is the reason why I found that an alder rod prepared for seeking out hidden waters, as it greedily drinks in the vapour coming from the ground, is eventually weighed down by it and tilts. What sufficed to provide the explanation of this affair was that it produces this result not at whatever time, but mostly before noon when the vapour is abundant; but at midday, when the vapour is used up, it is not the same; for then you will find that the alder rod, which earlier was tilting, now remains in balance. You will also experience this with scales, for if you take a pair with empty pans of equal weight and set one end over a pot full of hot water with the other remaining outside the vapour, you will observe that the pan placed over the pot, infected with the dewy vapour, outweighs the other: but when the vapour is exhausted or dried up they are restored to equality. Hence certain herbs growing over minerals are said to freeze mercury; by the Danube the tendrils and leaves of the vine are mostly appear gilded, the sign of a hidden vein of gold; saffron growing on sulphurous mountains, imbued with its power, tints tin with a golden colour. From this it is clear that this is a property of all trees and plants, although the metallic vapour shows this effect more distinctly when mixed with water. It is also clear from this why sometimes between the bark of trees copious