6 PREFACE TO THE HISTORIA VENTORUM. A comparison of the Historia Ventorum with the Physiologia Nova enables us to correct, in more than one case, the received readings. Gruter remarks that he is unable to decide whether the Physiologia was written before or after the treatise De Magnete, published in 1600. It was apparently written before 1604, as the new star of 1572 is mentioned by itself, whereas later writers, as Bacon and Galileo, always couple it with the star in Ophiuchus first seen in 1604. I should be inclined to conjecture that it was written between 1600 and 1604, principally on the authority of Bacon's remark, "Gilbertus postquam in contemplationibus magnetis se laboriosissime exercuisset, confinxit statim philosophiam consentaneam rei apud ipsum præpollenti ;"1 which is not however altogether conclusive. The description of a first-rate man of war is one of the most curious parts of the following treatise. I am inclined to believe that Bacon takes a portion of what he says of naval matters from some Italian writers, but cannot refer to any particular work. What is said of windmills seems to be derived from Bacon's own observation and experiments; it cannot be said that it is of much value. Between the vanes, according to Bacon, the air is compressed, and therefore reacts laterally. It did not occur to him to try whether a windmill with one sail only instead of four would remain stationary, as on his theory it plainly ought to do. On the other hand, he increased the number of vanes, thereby decreasing the intervals between them, and finding that this change increased the action of the wind, ascribed the difference to the increase of compression caused by the narrower space through which the air had to pass. That the whole amount of surface exposed to the wind was increased seems to have been forgotten. 1 Nov. Org. i. 54. 2 For an illustration of which see the frontispiece to this volume; which represents a first-rate of Henry the Eighth's time, and agrees with Bacon's description in every thing except the construction of the bolt-sprit. It is a reduced copy of an engraving said to be after an original by Holbein.-J. S. ILLUSTRISSIMO ET EXCELLENTISSIMO PRINCIPI, CAROLO, SERENISSIMI REGIS IACOBI FILIO ET HÆREDI. Illustrissime et Excellentissime Princeps, PRIMITIAS Historiæ nostræ Naturalis celsitudini tuæ humillime offero. Rem mole perpusillam, veluti granum sinapis; sed tamen pignus eorum quæ Deo volente sequentur. Obstrinximus enim nos ipsos tanquam voto, singulis nos mensibus ad quos Dei bonitas (cujus agitur gloria tanquam in cantico novo) vitam nostram produxerit, unam aut plures ejus partes, prout fuerint magis aut minus arduæ aut copiosa, confecturos et edituros. Moti etiam fortasse erunt alii nostro exemplo ad similem industriam; præsertim postquam penitus perspexerint quid agatur. Nam in Historia Naturali bona et bene instituta claves sunt et scientiarum et operum. Deus celsitudinem tuam diu servet incolumem. Celsitudinis tuæ servus humilis et devotus, FR. ST. ALBAN. |