Lives of the most eminent literary and scientific men of France, Vol. 1 (of 2)

by Mary Wollstonecraft Shelley

Various ways of further testing the evident inferences to be drawn from this beautiful experiment, were so obvious, that it is impossible to suppose the illustrious philosopher to whom we are indebted for it, would not have pursued the inquiry further, had not death, almost immediately after this, prematurely removed him. The experiment became known, and excited much interest in every part of Europe; and Mersenne, who had an extensive scientific correspondence, having received an account of Torricelli's investigation, communicated the particulars to Pascal. Always reluctant to surrender long established maxims, the philosophers of that day rejected the solution of the problem given by Torricelli, and still clung to the maxim that "nature abhors a vacuum." The sagacity of Pascal, however, could not be so enslaved by received notions; and he accordingly, assisted by M. Petit, applied himself to the discovery of some experimental test, of a nature so unanswerable as to set the question at rest. The result was the celebrated experiment on the Puy de Dôme, the first and most beautiful example of an "experimentum crucis" recorded in the history of physics.

Pascal argued, that if the weight of the incumbent atmosphere were the real agent which sustained the mercury in Torricelli's tube, as it was inferred to be by that philosopher, any thing which would diminish that weight, ought to diminish in the same proportion the height of the mercurial column. To test this, he first conceived the idea of producing over the surface of the mercury in the cistern in which the end of the tube was immersed, a partial vacuum, so as to diminish the pressure of the air upon it. But, apprehending that this experiment would hardly he sufficiently glaring to overcome the prejudices of the scientific world, he proposed to carry the tube containing the mercurial column upwards in the atmosphere, so as gradually to leave more and more of the incumbent weight below it, and to ascertain whether the diminution of the column would be equal to the weight of the air which it had surmounted. No sufficient height being attainable in Paris, the experiment was conducted, under Pascal's direction, by his brother-in-law, M. Périer, at Clermont, on the Puy de Dôme, a hill of considerable height, near that place. The experiment was completely successful. The mercurial column gradually fell until the tube arrived at the summit, and as gradually rose again in descending. Bigotry and prejudice could not withstand the force of this, and immediately gave way. The maxim of nature's abhorrence of a vacuum was henceforth expunged from the code of natural science; and, what was still more conducive to the advancement of all true science, philosophers were taught how much more potent agents of discovery, observation and experiment, guided by reason, are, than the vain speculations in which the ancients had indulged, and from the baneful influence of which scientific inquirers had not yet been emancipated.

1647.
Ætat.
24.

Pascal had hardly escaped from boyhood at this time; his invention, his patience, the admirable system he pursued of causing all his opinions to be supported by facts and actual experiment, deserved the highest praise and honour. It is mortifying to have to record that his discovery was disputed. The jesuits accused him of plagiarism from the Italians; and Descartes declared, that he had first discovered the effects produced by the weight of the atmosphere, and suggested to Pascal the experiment made on the Puy de Dôme. 1651.
Ætat.
28. Pascal treated these attacks the contempt which his innocence taught him that they deserved; and published an account of his experiments without making the slightest allusion to them. Descartes was a man of eminent genius—his industry and penetration often led him to make the happiest conjectures; but, more intent on employing his bold and often fortunate imagination in the fabrication of ingenious theories than on applying himself with patience and perseverance to the discovering the secrets of nature, he sometimes threw out a happy idea, which he did not take the pains to establish as a truth and a law. The honour of invention is due to those who seize the scattered threads of knowledge which former discoverers have left, and weave it into a continuous and irrefragable web. 1653.
Ætat.
30. Pascal followed up his experiments with the utmost hesitation and care, only deciding when decision became self-evident. Two Treatises, one "On the Equilibrium of Liquids," another "On the Weight of the Atmosphere," which he subsequently wrote, though they were not published till after his death, display his admirable powers of observation, and the patient zeal with which he followed up his discoveries. At the time that he wrote these treatises he was engaged on others, on geometrical subjects: he did not publish them; and some have been irrecoverably lost. Every subject then interesting to men of science employed his active mind. His name had become well known: he was consulted by all the philosophers and mathematicians of the day, who proposed questions to him; and his thoughts were sedulously dedicated to the solution of the most difficult problems. But a change meanwhile had come over his mind, and he began to turn his thoughts to other subjects, and to resolve to quit his mathematical pursuits, and to dedicate himself wholly to the practice and study of religion.

This was no sudden resolve on his part—piety had always deep root in his heart. He had never, in the most inquisitive days of his youth, applied his eager questionings and doubts to matters of faith. His father had carefully instilled principles of belief; and gave him for a maxim, that the objects of faith are not the objects of reason, much less the subject of it. This principle became deeply engraven in his heart. Logical and penetrating as his mind was, with an understanding open to conjecture with regard to natural causes, he never applied the arts of reasoning to the principles of Christianity, but was as submissive as a child to all the dicta of the church. But though the so to call it metaphysical part of religion was admitted without a doubt or a question, its moral truths met with an attention—always lively, and at last wholly absorbing; so that he spent the latter portion of his life in meditating, day and night, the law of God.

This change began first to operate at the age of four-and-twenty. His zeal overflowed to, and was imbibed by, all near him. His father was not ashamed to listen to his son's exhortations, and to regulate his life hereafter by severer rules. His unmarried sister, Jaqueline—the heroine of the tale previously narrated, who possessed singular talents—listened to her brother with still greater docility and effect: an effect rather to be deplored than rejoiced in, since it caused her to renounce the cultivation of her talents, and the exercise of active duties, and to dedicate herself to the ascetic practices of Catholicism.

Meanwhile the health of Pascal suffered severer attacks, and his frail body wasted away; so that before he attained the prime of life he fell into the physical debility of age. He resided at this time in Paris, with his father and his sister Jaqueline. To benefit his health, he was recommended to suspend his labours, to enjoy the recreations of society, and to take more exercise: accordingly, he made several tours in Auvergne and other provinces. 1651.
Ætat.
28. The death of his father broke up the little family circle. Jaqueline Pascal had long entertained the desire of becoming a nun: on the death of her father she put her resolve in execution, and took the vows in the abbey of Port Royal aux Champs. 1653.
Ætat.
30. The other sister resided with her husband at Clermont. Pascal, left to himself, devoted his time more earnestly than ever to studious pursuits, till the powers of nature failed; and he was forced, through utter inability, to abandon his studies. He took gentle exercise, and frequented society. Though serious even to melancholy, his conversation pleased by the depth of understanding and great knowledge that it displayed. Pascal himself felt the softening influence of sympathy: he began to take pleasure in society—he even contemplated marrying. Happy had it been for him if this healthy and sound view of human duties had continued: but an accident happened which confirmed him as a visionary—if we may apply that term to a man who in the very excess of religious zeal preserved the entire use of his profound arts of reasoning, and an absolute command over his will: yet when the circumstances of his exclusive dedication of himself to pious exercises are known, and we find that a vision forms one of them, that word cannot be considered unjust—nor is it possible to help lamenting that his admirable understanding had not carried him one step further, and taught him that asceticism has no real foundation in the beneficent plan of the Creator.

1654.
Ætat.
31.

One day, in the month of October, he was taking an airing in a carriage-and-four towards the Pont de Neuilli, when the leaders took the bit in their teeth, at a spot where there is no parapet, and precipitated themselves into the Seine: fortunately the shock broke the traces, and the carriage remained on the brink of the precipice. Pascal, a feeble, half-paralytic, trembling being, was overwhelmed by the shock. He fell into a succession of fainting fits, followed by a nervous agitation that prevented sleep, and brought on a state resembling delirium. In this he experienced a sort of vision, or extatic trance; in commemoration of which he wrote a singular sort of memorandum, which, though incoherent to us, doubtless brought to his memory the circumstances of his vision. This paper he always kept sewn up in his dress. The effect of the circumstance was to make him look on his accident as a call from Heaven to give in all worldly thoughts, and to devote himself to God. The pious exhortations of his sister, the nun, had before given him some notion of such a course; and he determined to renounce the world, and to dedicate himself exclusively to religious practices.