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pher, and led him away from earnest investigation to trifles, proved inimical to his success in experimental philosophy, in which he has left behind him the name of a zealous follower and promoter, but not the lasting reputation of a real discoverer.
The great type of the era, the true experimentalist, philosopher, and ingenuous inquirer into truth, was Robert Boyle, emphatically and justly entitled the Great Christian Philosopher. It has been remarked of this philosopher that he was born in the very year of Bacon's death, as though the natural successor of that great man. This, however, may place Boyle in too high a position—the character he fulfilled being rather that of a disciple of the Baconian philosophy than a master therein. Viewed in such a light, Boyle appears before us as one of the most laborious, patient, and perhaps one of the most successful of the early experimental philosophers. With his outward history we have nothing to do beyond to place on record the simple facts that he was born in 1627 and died in 1691. At Oxford, where Boyle associated with many of the professors of the colleges, and particularly with Dr Wilkins-a kindred spirit with his ownregular meetings were held for experiment and discussion. The knot of philosophers thus formed became convinced that a satisfactory knowledge of physical philosophy could only be gained by experiment; and accordingly all addicted themselves to practical research, communicating their discoveries to one another. Boyle perhaps, more than all the rest, proved his value for experimental investigation, and his contempt for the Aristotelian Philosophy in its application to natural objects. It is said that he would not even study the Cartesian Philosophy for many years, although it was become a general object of attention, lest he should be so biassed by any theory as to lose sight of his great principle—that nature will never be understood without a long series of experiments. In giving himself up to such inquiries, Boyle also indulged the benevolent bope that experimental philosophy might become attractive to men generally, and thus withdraw their attention from frivolous amusements, and the hateful contentions that at his period agitated the whole framework of society. The air was Boyle's great subject for investigation; and though other studies occupied much of his time and thoughts, yet this furnishes both the earliest and the latest evidences of the true experimental spirit which animated this philosopher. It appears that Otto Guericke had already performed several experiments upon the exsuction of air from glass vessels, and observed the rise of water into them. These experiments greatly interested Boyle, and he gives the correct interpretation of the rise of water in such vessels as being due to the pressure of the atmosphere. These experiments appear to have been carried on by means of a pump; so that Boyle was not the inventor of the instrument commonly attributed to him—the air-pump. He himself describes the apparatus employed for such experiments as very imperfect, and in the following terms :—The wind-pump, as somebody not inappropriately calls it, is so contrived that to evacuate the vessel there is required the continual labour of two strong men for divers hours; and next (which is an imperfection of much greater moment), the receiver or glass to be emptied, consisting of one entire and uninterrupted globe and neck of glass ; the whole engine is so made that things cannot be conveyed into it whereon to try experiments.' In a word, Otto Guericke's 'wind
pump' was a clumsy, ill-made philosophical toy. Boyle, by his attention to the subject, and with the assistance of Hook, turned it into an excellent apparatus for the experimentalist. It is due, however, to Boyle to state, that several years before his attention had been turned to the subject, and a series of experiments upon the vacuum left by the removal of air had been made. The improvement and perfection of the air-pump were not accomplished, however, without difficulty, and this of various kinds. Boyle himself confesses that after innumerable trials, and all the improvements he could devise, he found it so exceeding and inconceivably difficult a matter to keep out the air from getting at all in, that in spite of all his care and diligence he was never able totally to exhaust the receiver, or keep it, when almost empty, any considerable time from leaking, more or less. He had, however, perfected it sufficiently to enable him to discover hitherto unobserved phenomena of nature.
The instrument thus completed furnished Boyle with experimental occupation for half his lifetime, and was a great attraction to the learned of the day. It was a wonder of inexhaustible freshness to pump out the air from this machine, and request a bystander to lift the brass plug held down by the presence of the invisible column of air above. When a bladder was substituted for this stopper, and the air moderately exhausted, “it is pleasant,' writes Boyle, 'to see how men will marvel that so light a body should forcibly draw down their hand as if it were filled with some ponderous thing.' Not only wonder, but perplexity was created by many of these simple experiments performed by Boyle in the presence of many 'mathematical and philosophical spectators of his engine.' It was to them incomprehensible how the air contained within the receiver, separated as it is by the glass wall of the vessel from that without, should be considered to have a pressure equal to that without. Boyle explained this over and over again to these philosophers, and to their satisfaction proved that such was the case, and that the pressure of the interior air in bollow bodies balancing the pressure of the external prevents the injury to the walls of the vessel that would otherwise ensue. All the experiments which are now adopted by lecturers on natural philosophy in illustrating this subject were originated by Boyle. He laboured hard to establish what he denominates the spring of the air '—in other words, its elasticity and pressure—in opposition to the schoolmen who, quietly folding their arms, referred all the phenomena they beheld to the old dogma-nature's abhorrency of a vacuum; whereas, as Boyle justly observes, such effects ' seem to be more fitly ascribable to the spring and weight of the air.' By a variety of illustrations Boyle shewed the elasticity of the air. He took a flaccid bladder, tightly tying its neck, and placed in the receiver of his air-pump-on exhausting the latter, the bladder plumped up until it became fully distended, shrinking back again to its original size on the Teadmission of the air. He observed that the bladder could even be burst by continuing the exhaustion. He also made the interesting and homely experiment of strongly tying a bladder moderately filled with air; and holding it near the fire, it not only grew exceedingly turgid and hard, but afterwards being brought nearer to the fire, it suddenly broke into so loud and vehement à noise as stunned those that were by, and made us for awhile almost deaf.' Both these effects Boyle justly ascribed to the expansibility of the air : in the one case, by the removal of the compressing force—the pressure of the external air ; in the other, by the influence of heat in 'separating or stretching out' the aërial particles. He also assiduously endeavoured to ascertain the limits to which the air could be dilated ; and his experiments led him to the conclusion-an incorrect one, yet apparently justified by his investigations—that it could expand almost indefinitely.
Boyle's experiments did not end with the mechanical properties of the air-with the determination of its elasticity, density, weight, and pressure. He performed a series of highly-interesting and important investigations upon its chemical properties—its relation to respiration and life, to combustion and flame. That "famous mechanician and chymist, Cornelius Drebbel,' is related to have contrived for the learned King James a vessel to go under water, of which a trial was made in the Thames, the vessel carrying twelve rowers besides passengers ; 'one of which,' relates Boyle, 'is yet alive, and related it to an excellent mathematician that informed me of it.' Boyle, dissatisfied with the account, yet fully believing in its credibility, made further inquiries, which disclose to us a very remarkable fact—no less than that oxygen gas must have been discovered by this Drebbel. We may take the account of his subinarine navigation as a myth, for such unquestionably it was. But, like all myths, it had a nucleus of fact, around which the fabulous concretion had formed. One of his earliest, in fact the earliest, work of this great philosopher's composition related to the air ; and death removed him before he could complete his last-still on the same subject—which had engaged so large a portion of his time and so lavish an outlay of his fortune.
Yet Boyle was not without the infirmities characteristic of the philosophers of his time, and this renders him the truer type, as he is the best model of them. He firmly believed in the efficacy of the touch of one Valentine Greatrix, who went by the name of Valentine the Stroker, from the asserted fact of his being able, in common with royalty at that privilegedperiod, to cure scrofulous diseases, and, it is said, even after the royal touch had failed. Numberless other examples of his readiness to believe might be collected out of his little tract called Strange Reports,' and from his other writings. But with all this Boyle was a great man and a true philosopher. Seeking after truth for its own sake, he has left a reputation for philosophical attainments and discoveries equalled by none of those who were his contemporaries in that inquiring period. Boerhaave has said of him : • Which of Mr Boyle's writings shall I commend? All of them. To him we owe the secrets of fire, air, water, animals, vegetables, fossils; so that from his works may be deduced the whole system of natural knowledge.” And Dr Johnson pays him the following tribute in the Rambler : It is well known how much of our philosophy is derived from Boyle's discoveries, yet very few have read the detail of his experiments. His name is indeed reverenced, but his works are neglected; we are contented to know that he conquered his opponents without inquiring what cavils were produced against him, or by what proofs they were confuted.'
There were others living in those days whose connection with philosophy -especially with the experimental philosophy—is interesting, though less important than that of the virtuosi we have alluded to. These were men
full of ardour for science, and possessed of considerable attainments in various studies, but not themselves so much experimentalists as narrators and collectors of the experiments of others. To the indefatigable exertions of one of these is due the existence of the ' Philosophical Transactions 'the busy, hard-working Mr Henry Oldenburg, who, out of a common piece of wit in the day, was accustomed not unfrequently to call himself by the curious name of Grubendol, reversing the letters of his name. It would be scarcely doing justice to his labours, considering his intimate connection with science in his infancy, were we to pass him by without a more direct allusion than has hitherto been made. Mr Oldenburg was early associated with the prosecution of scientific experiments at Oxford, and subsequently at London. He was also early admitted a Fellow of the Royal Society, and in a short time he began to act as secretary to that philosophical association. At first this appears to have been purely a labour of love; but subsequently he was elected secretary, and was of all others most diligent in the record of experiments, and in carrying on the scientific business of the society. His occupation in this capacity may be judged of by the account he has given of the business of the Sec. of the R. S. He attends constantly the meetings both of the Society and Councill, noteth the observables said and done there; digesteth them in private; takes care to have them entered in the journal and registry-books ; reads over and corrects all entrys; sollicites the proformances of taskes, recommended and undertaken ; writes all letters abroad, and answers the returns made to them, entertaining a correspondence with at least fifty persons; employs a great deal of time, and takes much pains in satisfying foreign demands about philosophical matters; disperseth farr and nearre stores of directions and enquiries, and sees them well recommended.' No secretary could have been more assiduous than was Mr Oldenburg; but he soon began to entertain the thought that it was a pity that all this scientific information should be contained in a private form. And in a little while it was decided that selections of the scientific communications made to the society of philosophers should be published under Mr Oldenburg's care.
To this fresh undertaking the zealous amateur philosopher applied himself with all the powers of bis mind, and with the method of a man of business. His scientific correspondence now increased enormously. It is said that at one time he, without any assistance, corresponded with seventy different philosophers on various scientific subjects, and in different parts of the world. The labour was immense, and the contents of the Philosophical Transactions' shew the assiduity with which philoso-phical information was culled from all quarters. His plan of getting through this vast amount of work was admirable: the moment he received a letter be perused it, and immediately wrote back the answer. Thus his work never grew upon him, and though great and burdensome, never became insupportable. He alone, greatly to his credit, bore the responsibility of the expense connected with this undertaking, which was his own, and had no official connection with the Royal Society. In virtue of his diligence, the 'Philosophical Transactions' assumed an important position, but as yet only in the form of a scientific miscellany ; for such in reality the earlier volumes are. Yet the sale of them at first only averaged about three hundred copies, and Mr Oldenburg complains of receiving a very heavy letter from the printer upon the subject. In spite, however, of all discouragements, Oldenburg pursued his task. During the terrible visitation of the plague in London, he never quitted his post. He lived in Pall Mall, and carried on his customary correspondence on scientific matters uninterruptedly. At length death closed the career of this anwearied though humble servant of the new philosophy, and his editorial pen passed into other hands. During his lifetime he was once imprisoned in the Tower. Oldenburg was a man indispensable to experimental science in its infancy, although not directly connected with its advance. No doubt his zeal and enthusiastic devotion to the cause of the philosophy now being made trial of, stimulated and quickened those of others who were more successful labourers in the laboratory and workshop than himself. He was born to fulfil the office to which he was elected, and which he so long honourably maintained. And no one who admits the necessity of the interchange of thought and knowledge among philosophers to the ultimate advancement of philosophy, will refuse to Henry Oldenburg, with all his credulity and childlike simplicity, a place and name in the records of experimental science. Another celebrated personage who was much connected with early philosophy and its followers was John Aubrey. This gentleman found vast delight in the experiments of the infant philosophic associations, and from his incessant bustle and insatiable curiosity received the naine of the Carrier of Conceptions of the Royal Society. Not & philosopher himself, but much attached to the sciences, and especially enchanted with any mysterious things connected with them, he was one of the busybodies of the time, doing little or nothing, directly or indirectly, to further the progress of the philosophy he admired, but perhaps often did not comprehend.
The records of experimental philosophy in England have presented us with a sufficient number and variety of instances illustrative of the state of the scientific mind of the period; and those of other countries are rich in similar illustrations, to which, as they all indicate the same general features, it has been thought unnecessary to refer. The names of Schottus, Porta, and, above all, of the clever but credulous and superstitious Jesuit, Athanasius Kircher—the best type of an Italian child-philosopher-appear prominent in the history of this period, and may form useful references to those who would inquire into the condition of experimental philosophy abroad as well as at home. It is sufficient for us here to state that the same love of toys and trifles, the same eagerness of inquiry and simplicity of belief, and the same or even a greater degree of superstition prevailed, and gave to the philosophy of the period its childish aspect.
In reviewing the state of science at this period, confining our attention chiefly to our own country, it is highly remarkable to find the persistance with which philosophers clung to their determination to interpret nature solely by means of experiment. The results soon became apparent. The records of philosophy began to teem with new discoveries— facts multiplied, leading phenomena became prominent, laws began to emerge, and generalisations to commence.' Although the labourers were few the barvest was ripe, and only awaited the ingathering of the philosophical husbandmen. It is worthy our notice to glance over the memorabilia of this time. Immediately prior to it Galileo Galilei discovered the true motion of the earth,