The fame of Torricelli’s experiments had reached Paris as early as 1644, before their formal publication. Some one, Pascal says, had communicated them to Father Mersenne—both a religious and scientific intimate, as we have already seen, of the Pascal family. Mersenne had tried the experiments for himself, at first without success, but soon with better fortune, after he had been to Rome and had learned more fully about them. “The news of these having reached Rouen in 1646, where I then was,” says Pascal, {31} “I made the Italian experiment, founding on Mersenne’s account, with great success. I repeated it several times, and in this manner satisfying myself of its accuracy, I drew certain conclusions from it, for the proof of which I made new and very different experiments in presence of four or five hundred people of all sorts, and amongst others, five or six Jesuit fathers of the College of Rouen.” When his experiments became known in Paris, he adds, they were confounded with those which had been made in Italy, and the result was that some attributed to him a credit which was not his due, while others, “by a contrary injustice,” were disposed to take away the credit of what he had really done. It was with the view of placing the matter in a clear light, and vindicating his own share in the train of experiments which had been made, that he published in 1647 his “Nouvelles Expériences touchant le Vide,” the first of his hydrostatical treatises. He was at pains to explain the distinction betwixt his own experiments and those which had been made in Italy; and not content with this, he added in express words, in an “avis au lecteur,” that he “was not the inventor of the original experiment, but that it had been made in Italy four years before.” So little, indeed, did Pascal borrow directly from Torricelli, or seek to appropriate the fruits of his researches, that he was as yet ignorant of the explanation which the Italian had suggested of the phenomenon so fully established. He saw, of course, that the old maxim of Nature abhorring a vacuum had no solid foundation; but he tried to account for the vacuum above the water and the mercury by such a supposition as the following:— “That it contained no portion of either of these fluids, or of any 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 about 32 feet in height, and that beyond this limit a great or small vacuum is formed above the water with the same facility, provided that no foreign obstacle interfere to prevent it.”