On the Magnet

A decorative drop cap 'S'.Should there chance to be (most grave sir) anyone who sets little value on these magnetic books and your labor, and who thinks these studies are too light and by no means worthy of a grave man consecrated to the more serious studies of medicine, surely he should be judged as not insignificantly deluded. For it is known even to men of the lowest sort that the use of the magnet is the greatest and truly admirable, so much so that it stands in no need of my oration at this time or any lengthy commendation. Nor indeed (in my judgment) could you have chosen any argument more noble or more useful to the human race in which to exercise the powers of your philosophical genius. For it is by the divine benefit of this stone that those things which for so many centuries, and across such vast continents of the world, and such an infinite number of regions, islands, peoples, and nations, lay unknown, have now been detected and explored in our own memory more easily and frequently; and the circumference of the entire terrestrial globe has been circumnavigated, even by our own Drake and Cavendish (which I wish to be said in their perpetual memory), more than once. For by the indication of iron touched by a magnet, the points of the south, north, east, and west, and other quarters of the world, have become known to those sailing under a dark sky and in the most obscure night; from which they have always most easily understood toward which part of the world they should direct the course of their vessel; which was entirely impossible before the invention of that most admirable virtue of magnetic βορεοδείξεως north-pointing. Hence, in the past (as is evident from histories), incredible anxiety and huge danger often threatened sailors, when, with a storm approaching and the sight of the sun and stars removed, they were totally ignorant of where they were heading, nor could they investigate this by any reason or artifice. With how much joy, therefore, must we think all ship captains were filled? With what happiness did they exult when this magnetic index first presented itself to them as a most certain guide of the way, and as a kind of Mercury? But neither was this enough for this magnetic Mercury—to point out the way itself, and to point as it were with a finger toward which the course should be directed; it began also, long ago, to show the distance of the place itself toward which one is heading. For when the magnetic index is not always the same in every...