“A time would come when men would be able to stretch out their eyes as snails do (Wren worked with a thirty-six foot glass at Oxford) and extend them to fifty feet in length, by which means they should be able to discover ten thousand times as many stars as we can.” Of this Professor Hinks says, “Rather poor stuff, suddenly rising into this most interesting conclusion—‘and find the Galaxy to be myriads of them, and every nebulous star appearing as if it were the Firmament of some other world ... bury’d in the vast abyss of intermundious vacuum.’ What would we not give [Professor Hinks continues] for fuller knowledge of what was in Wren’s mind when he wrote this passage so strangely before its time, so strongly suggestive of the island universe theory of spiral nebulæ to-day.” There was also the matter of the method for constructing solar eclipses. The lay reader may be spared bibliographical details, into which I have dived, but Professor Hinks makes this significant comment: “Wren was the first to discover the graphical method of computing eclipses that, with some modifications due to much improved tables, remains by far the most instructive, though not the most numerically accurate way of calculating ... and is in use to-day for the graphical prediction of occultations.”
It was a practical thought of Wren that the Monument should be used as a gigantic telescope, and members of the Royal Society tried so to use it, but failed, because passing coaches caused vibrations. He had a like idea for the great south staircase at St. Paul’s, but again, for practical reasons, it broke down.
The biographers of Wren have made great play with a story taken from a manuscript bound up in the heirloom Parentalia. Miss Milman referred to “the problem which Pascal, ... under the pseudonym of Jean de Montfert, challenged the mathematicians of England to answer by a certain day. He accompanied the challenge with a promise of a prize of twenty pistoles to the successful competitor. Christopher Wren solved the problem, but for some unexplained reason never received the prize, while the problem from Kepler which he set in return seems never to have been solved.” The facts are rather different. In June, 1658, Pascal put out a challenge to all mathematicians (not English alone) to find a solution for certain problems connected with a cycloid, the curve described by a point on the circumference of a circle when that circle rolls along a straight line—e.g., a nail on the rim of a carriage-wheel.
In an appendix I set out the story as it has been given me by Sir Daniel Hall. It is rather technical, but may be summed up simply. Pascal received both attempts at solutions and replies which merely discussed germane matters. Wren sent a partial but admirable contribution, unfortunately “without demonstration.” It was original as far as it went, but not the complete solution for which Pascal had asked. Cavarci, the umpire in this high contest, wrote that Wren had merely solved the easy part of it.
It appears clear that in withholding the prize Pascal wronged neither Wren nor the other contestants. The suggestion that Wren was the master mathematician of Europe will not do. It is enough to affirm of him that he was an ingenious geometrician who made several minor advances in that science. He left no evidence of mathematical genius, a quality which ought to be reserved to the authors of far-reaching and fruitful conceptions. The true significance of Wren’s mathematics lies in the fine way in which he applied them in his buildings. No one is a better representative of applied science as compared with pure or fundamental science. Too much has also been made of Wren’s work on the barometer. Some enthusiasts have, indeed, tried to transfer to him the credit which belongs to Torricelli and Pascal.
Wren repeated Torricelli’s experiment at the top and bottom of a hill, and finding that the mercury column stood at a lower height on the top of the hill, argued that the mercury was really balanced by the weight of the air, or, as we now say, measured its pressure. But in this experiment Wren was anticipated by Pascal; his experiment was regarded by his contemporaries as made independently, but it would be hard to say that the experiment was really Wren’s own device, so much was the question a matter of discussion among the men of science of the time. The enunciation of the laws of impact was made practically simultaneously by Wallis, Wren, and Huygens. Wren’s may be regarded as the most elegant demonstration, but it was Huygens alone who perceived that when the colliding bodies are perfectly elastic the energy of the system, i.e., the sum of the products of the mass of each of the bodies multiplied by the square of its velocity, remains unchanged—one of the generalisations at the base of modern science. Similarly, although Wren became Professor of Astronomy both at Gresham College and then at Oxford, no outstanding observation or fundamental discovery remains attached to his name. Speaking broadly and generally we can say that Wren was universally accomplished in all the science of the time, that in several directions he showed a quality of mind that was only short of the highest, and that finally he abandoned the pursuit of pure science too soon to have accomplished in any branch such a mass of work as would mark him as one of the founders of that science. It must always be remembered that Wren took to architecture when he was just over thirty, and was immersed in a huge practice when he was thirty-five.
But perhaps Wren also was too universal. Perhaps the very ingenuity of his mind led to distractions in too many directions. It may be, too, that his inclinations towards the practical fusion of art, science, and administration, which found full expression as an architect, had always tended to draw him away from the pursuit of abstract science. We may notice that even in the early days of Oxford he was always the demonstrator and the contriver of experiments at the meetings of the philosophers, and later, in the early history of the Royal Society, we find that it was to Wren that the Society continually turned for the solution of almost any problem that came under discussion. A letter he wrote to Lord Brouncker in 1663, as to an appropriate show when the King visited the Society, suggests he was already distrusting his own skill and pleasure in experiment. “Sciographical Knacks (of which an hundred sorts may be given) are so easy in the invention, that now they are cheap.”
The extracts from the Minute Books of the Royal Society show the confidence of its members in Wren’s universality of mind and constructive ability. At the second meeting of the Society on December 5, 1660, when Sir Robert Moray brought the King’s approval, “Mr. Wren was desired to prepare against the next meeting for the pendulum experiment.” A fortnight later the record states “that Dr. Petty and Mr. Wren were desired to consider the philosophy of shipping ... and that Mr. Wren bring in his account of the pendulum experiment.”
Wren was at Oxford in the Spring of 1661, and things did not go well without him. On May 8 we find a resolution that a letter be sent him charging him in the King’s name to make a globe of the moon and likewise to continue the description of several insects that he had begun. Sir Robert Moray transmitted the royal command in a very affectionate letter. The moon was duly delivered to the King at Whitehall, who received it with great satisfaction.
On September 4 there is reported some correspondence with Sir Kenelm Digby and Monsieur Frenicle concerning Wren’s hypothesis about Saturn’s rings. Later there is a letter of Wren’s which records that, although in 1658 he had made a model to illustrate his theory of Saturn’s rings, he had withdrawn this hypothesis as soon as he had learnt of Huygen’s more convincing explanation.