ASTRONOMY PROFESSORSHIP.
Soon after this he was summoned to London. The Gresham professor of astronomy, Mr. Laurence Rooke, retired in 1657, and the chair was offered to Wren. He was but twenty-four and doubted whether he should accept such a post while so young, and he clung to Oxford and his studies there.
The friends whom he consulted advised him differently; accordingly he came up to London and delivered his opening address to a considerable audience. It was in Latin, and after a brief apology for his youth passed into a sketch of the history of astronomy. He dwells on the great riches of the science, how it is the handmaid of theology, the queen of sciences, speaks of the vast discoveries made by its means, touches upon Copernicus, whose mind first grasped the idea that the earth moved round the sun, then upon Kepler and upon Galileo, and the storms that had arisen, when in 1632 he had demonstrated that truth at which Copernicus had guessed; he praises highly Galileo’s invention of the telescope, pays a tribute to the great men who had lectured at Gresham on these subjects, and especially to his own predecessor, Rooke, and winds up with an eloquent description of London as a Pandora of cities to whom each of the choir of planets gave a peculiar blessing, on whom the sun shines benignly, who possesses more inhabitants than any city in the world, a healthy air, a fertile soil stretching far around her, beautiful buildings springing as of themselves from the earth, and, lastly, is blessed by the moon, ‘the governess of floods,’ who alluring the seas thus far inland by means of the beloved Thames, makes her the city which nourishes the best seamen of the world. The rough draft of this address, written by Christopher in a bold hand with a few changes and corrections, is preserved in the ‘Parentalia.’
This professorship obliged him to come up to London and give a course of lectures every Wednesday in term time at Gresham College. None of these lectures have been preserved, and it seems from a hint in one of Dr. Sprat’s letters, that Wren was in the habit of lecturing from rough notes merely, and used no pains to keep any record of them.
‘HE MAY COME OUT AN HE WILL.’
At this time he made acquaintance with Richard Claypole, who was married to Elizabeth, Cromwell’s favourite daughter; both she and her sister, Lady Falconbridge, were faithful members of the persecuted Church of England. Dr. Hewet still read the Prayer Book services in S. Gregory’s Church, which adjoined S. Paul’s, and there the two sisters resorted, there Dr. Hewet secretly married Mary Cromwell to Lord Falconbridge, as neither would be satisfied with the ceremony performed by an independent preacher. Cromwell’s daughters used all their influence with their father on the side of mercy, but when the excellent Dr. Hewet fell under his displeasure they pleaded in vain for his life.[64] Mr. Claypole professed a fondness for mathematical science and frequently invited Christopher Wren to his house. On one of these occasions when Wren was dining there, Cromwell himself entered, and, as was his custom in his own family, sat down to table without speech or ceremony. After a while he fixed his eyes on Christopher and said, ‘Your uncle has been long confined in the Tower.’ ‘He has so, sir,’ said Wren; ‘but he bears his afflictions with great patience and resignation.’ ‘He may come out an he will,’ was Cromwell’s unexpected reply. ‘Will your Highness permit me to take him this from your own mouth?’ said Wren, hardly able to believe his ears. ‘Yes, you may,’ said Cromwell briefly. At the earliest possible moment Christopher hurried to the Tower to communicate to his uncle the tidings that the long years of his imprisonment were over. When he had poured out his news the Bishop replied warmly that it was not the first time he had received the like intimation from that miscreant, but he disdained the terms proposed for his enlargement, which were a mean acknowledgment of his favour and an abject submission to his detestable tyranny; that he was determined to tarry the Lord’s leisure, and owe his deliverance, which was not far off, to Him only. Such an answer must have been startling enough to Christopher, and may have opened his eyes to the causes of Cromwell’s seeming leniency. He left the brave old man to await the deliverance which the keen sight of faith showed him as drawing near, and returned to his own work.
The death of Mrs. Claypole in the following summer must have checked an intimacy upon which Bishop Wren looked with little favour. She died of a terrible illness, and in the paroxysms of her pain bitterly reproached Cromwell for the innocent blood that he had shed, and particularly for that of Dr. Hewet.
At about this period some experiments were made by Wren’s philosophical friends wherein he took a principal part, and to which the barometer, now in common use, is mainly due. The first instrument of the kind was invented by Torricelli, the pupil of Galileo, who used it in order to ascertain the pressure of the air on fluids, the supposed cause of which pressure was the passing by of the body of the moon. Pascal, in those earlier days when his great genius employed itself on natural philosophy, made several experiments at Rouen, in 1646, with a friend, M. Petit, using ‘Torricelli’s tube,’ as it was called. Similar trials were afterwards made by M. Perier, his brother-in-law, among the mountains of Auvergne. They then discovered that the rising and falling of the mercury was due not to the moon, but to the differences in the specific gravity of the atmosphere. Wren’s experiments led him to the same conclusion, and at a later period he and Robert Boyle continued them until they produced the barometer, though it was not used commonly as a weather-glass until a much later date. Pascal did not pursue his discovery, but was satisfied with having proved the point for which he was contending.
THE CYCLOID.
Though Wren and Pascal never met, some communication passed between them. Pascal, who was Wren’s senior by eleven years, propounded a problem, under the name of Jean de Monfert, to the mathematicians of England, adding a challenge to them to solve it by a given day. Christopher sent a solution, and in his turn propounded a problem which seems never to have been answered. Pascal is said to have considered Wren’s solution very carefully, but the promised prize of twenty pistoles was withheld by some trickery. Besides this, Wren wrote four mathematical tracts on the cycloid, and sent them to Dr. J. Wallis, who was publishing a book on mathematics. He corresponded with Pascal,[65] who was writing on the cycloid by the name of la Roulette, the problem being ‘to determine the curve made in the air by the nail of a coach wheel from the moment it rises from the ground, till the moment when the continual rolling of the wheel brings it back to the ground, after a complete turn, supposing the wheel a perfect circle and the ground perfectly level.’