"When the engineers of Cosmo de Medicis wished to raise water higher than thirty-two feet by means of a sucking-pump, they found it impossible to take it higher than thirty-one feet. Galileo, the Italian sage, was applied to in vain for a solution of the difficulty. It had been the belief of all ages that the water followed the piston, from the horror which nature had of a vacuum, and Galileo improved the dogma by telling the engineers that this horror was not felt, or at least not shown, beyond heights of thirty one feet! At his desire, however, his disciple Toricelli investigated the subject. He found, that when the fluid raised was mercury, the horror of a vacuum did not extend beyond 30 inches, because the mercury would not rise to a greater height; and hence he concluded that a column of water 31 feet high, and one of mercury 30 inches, exerted the same pressure upon the same base, and that the antagonist force which counterbalanced them must in both cases be the same; and having learned from Galileo that the air was a heavy fluid, he concluded, and he published the conclusion in 1645, that the weight of the air was the cause of the rise of water to 31 feet and of mercury to 30 inches. Pascal repeated these experiments in 1646, at before more than 500 persons, among whom were five or six Jesuits of the College, and he obtained precisely the same results as Toricelli. The explanation of them, however, given by the Italian philosopher, and with which he was unacquainted, did not occur to him; and though he made many new experiments on a large scale with tubes of glass 50 feet long, they did not conduct him to any very satisfactory results. He concluded that the vacuum above the water and the mercury contained no portion of either of these fluids, or any other matter appreciable by the senses; that all bodies have a repugnance to separate from a state of continuity, and admit a vacuum between them; that this repugnance is not greater for a large vacuum than a small one; that its measure is a column of water 31 feet high, and that beyond this limit, a great or a small vacuum is formed above the water with the same facility, provided no foreign obstacle prevents it. These experiments and results were published by our author in 1647, under the title of Nouvelles Experiences touchant le Vuide; but no sooner had they appeared, than they experienced, from the Jesuits, and the followers of Aristotle, the most violent opposition."