of magic, and to have his works despised by such as never read them, or were incapable of comprehending them if they had. The remarkable men, who succeeded Bacon in the pursuit of natural knowledge, studied it rather as chemists than philosophers they applied themselves to the analyzation of particular bodies by fire, and to their uses in medicine, rather than to consider nature with a general view, to the discovery of the laws of her operations. Though they were rich in a variety of curious and useful discoveries, yet they knew nothing, for instance, of the laws of motion, or the properties of fluids, upon a knowledge of which the whole system of modern philosophy is founded. The great man, to whom experimental philosophy next owed its obligations, was of the same name and the same country with the former. Francis Bacon, Lord Verulam, first discovered the general principles, which were to serve as guides in the study of nature. He first proposed the usefulness of experiments alone, and hinted at several, which others afterwards made with success. He set out with taking a general survey of natural knowledge, divided it into its parts, inquired into the degree of perfection at that time attained by each. He considered philosophy as only an instrument, which made us better or happier; and, an enemy to all systems, exhorted men to study only what was useful. This great man having thus broke through many of the chains in which true science was bound, was still deterred from attempting others, which prejudice and authority seemed to fasten. In this review of experimental philosophy, Des Cartes must not be passed over, although mentioned rather for his fame than his services. He contributed not a little to explode the errors of scholastic philosophy; but, unfortunately, it was to substitute his own. Though he was very capable of reasoning closely, yet, to accommodate his philosophy to the multitude, he drew up rather a romance than a system. Like all works that strike the imagination, it pleased while new; but, wanting the basis of reason, the whole fabric has long since fallen to the ground. As his hypothesis, however, has been once embraced by the greatest part of Europe, and still continues to have its partisans, it may not be amiss to give the learner a superficial idea of it. 66 It is on all hands acknowledged, that the most obvious appearances in nature are those which are least understood. Why, for instance, a stone, when thrown upward, should fall to the ground back again, and not continue to go up to the skies, is one of those difficulties, which, though disregarded by the vulgar, has puzzled the philosophers of every age. To express it more philosophically, the descent of bodies to the surface of the earth is a phenomenon long sought after without success, and for the cause of which Des Cartes thus attempted to account. We are certain, from astronomical observations," says he, "that the earth turns continually round upon itself, like a top, with a very rapid motion, carrying with it every thing immediately attached to its surface. But, though the earth thus moves with great swiftness, yet there is diffused around it a very subtle matter, which, as it has less weight than the earth, has therefore much greater velocity, the lightest bodies being the most easily moved: so that this subtle matter whirls round the earth infinitely faster than the earth itself can move. If, therefore, a stone is thrown from the earth's surface upward into this subtle matter, it must soon be pressed downward by it to the earth again, in the same manner as if a person, in the midst of a whirlpool, should throw a plank from him into the surrounding current; this plank would be soon driven back to him in the centre again by the circulating fluid, and he could never by such means get free. In this way every one of the planets may be considered with its vortex or whirlpool of subtle matter turning round it, and pressing all the bodies that are thrown upward back upon its surface." Besides these particular vortexes in which each moved, they were represented as having altogether one common vortex, which regulated their motions, and in this manner all their revolutions were in the gross accounted for. An hypothesis thus formed by the fancy was liable to a thousand objections, which were drawn from experience. Each of these, the followers of Des Cartes endeavoured to answer, till at length the whole philosophical machine was found so much clogged, that it became utterly disregarded by its warmest asserters: they therefore quitted a fortress, which they found could be assailed on every side with advantage. But, notwithstanding all his errors, he diffused a passion for natural knowledge, and excited a spirit of inquiry, which insensibly spread itself over Europe. The academy of Cimento at Florence, Boyle, Mariotte, Torricelli, Huygens, and Pascal, all improved philosophy by producing new objects of speculation. The societies of London and Paris still farther enlarged the landmarks of the science, and adopted the experimental methods of investigating nature. Though they had not yet arrived at the true system of nature, yet they might justly be said to be on the road. At length Newton appeared, who first effected what his predecessors had hitherto only aimed at; namely, the application of geometry to nature, and, by uniting experiments with mathematical calculations, discovered new laws of nature, in a manner at once precise, profound, and amazing. Whatever all his predecessors, from time immemorial, had handed down concerning this science, does not amount to the tenth part of the discoveries of the English philosopher only. Equally conspicuous for his researches in optics, as for his system of the world, he had the pleasure of seeing his countrymen at once seize the truths he revealed to mankind. France, for some years, rather through national prejudice than philosophical conviction, opposed his fame, and in their academies and universities continued to teach the opinions of their countryman Des Cartes. Truth, however, at length prevailed: the contemporaries of Newton, who might have opposed his merits from envy, being deceased, the succeeding generation adopted his discoveries, and his system now prevails in every polite part of Europe. Thus far we have seen experimental philosophy continuing to improve; but it will be but justice to observe, that the successors of Newton have not since his time made that rapid progress in this science that was once expected. This judicious philosopher knew precisely those parts of nature which admitted of geometrical applications. Nothing could be more happily conceived than his applying mathematical calculations to the heavenly bodies, upon which no natural experiments could be made, and the greatness of whose bulks and distances could more easily be measured by numbers, and conceal the minute deviations of nature from universal theorems. His followers, much less judicious, have expected more from geometry than the art could grant; and, by erroneous imitation, have applied it to parts of nature which are incapable of admitting mathematical calculations. Thus we have seen the force of muscular motion determined by numbers ; the velocity with which the blood circulates calculated with geometrical precision; the fermentation of liquors has undergone the same scrutiny; and the most inconstant appearances of nature have been determined with inflexible demonstration. It would be absurd to deny the great use of geometry in natural inquiries; but sure it may be said, without offence, that mathematicians expect more from its assistance, than they have been hitherto able to find. If we expect to make discoveries in nature merely by the helps of geometry, it is probable we shall be disappointed, as this art is rather fitted to give precision to discoveries already made, than to conduct us to new. Though it may serve as a vehicle, through which to deliver our discoveries to others, yet it is seldom by this method that we have happened upon them ourselves. However this may be, it is rather to accidental experiments, than to painful inductions, that we are indebted for the modern discoveries in this science. Electricity, magnetism, and congelation, have been rather the result of accident than of investigation. Of these we know but some of the properties; nor have we any substantial theory as yet concerning them. In fact, mankind at last begin to perceive, that our knowledge of nature is much more limited than we lately imagined it to be. In the last age it was fashionable to suppose, that we could satisfactorily account for every appearance around us at present, the real philosopher seems to rest satisfied, that there is much in this science yet to be discovered, and that what he already knows bears no proportion to what remains unknown. He no longer, therefore, pretends to assign causes for all things, but waits till time, industry, or accident, shall bring new lights to guide the inquiry. |