Sir Christopher Wren

The sketch of Wren’s activities at Wadham (in Chapter II) shows the variousness of his mind, but clearly his many inventions, though they make an astonishing list, were juvenilia. His contemporary Hooke said of him, “Since the time of Archimedes there scarce ever met in one man in so great perfection such a mechanical hand and so philosophical a mind”; and he describes a method of determining the parallax of comets “invented by that incomparable mathematician Dr. Christopher Wren.”

In estimating the value of such an opinion, one of very many, I am bound to rely on the judgment of scientific friends who have generously helped me with this chapter, because I can only repeat Professor Lethaby’s comment on the same text: “These things are beyond my knowledge, but I know that they represent wonderful powers.”

We shall only understand the part played by Wren in the development of natural science if we see that development as the work of a team rather than of individuals. Wilkins, Boyle, Lawrence Rooke, Hooke, Seth Ward, Wallis, Scarborough, Oughtred, Wren and many another shared a common enthusiasm for the advancement of knowledge which showed itself in common effort. Wren was the man to whom his associates turned for help in solving their individual problems, because of his extraordinary ingenuity in inventing apparatus which would establish or dispel the truth of some scientific idea, and still more because of his ready kindness and modesty. During the early days of the Royal Society he was not only in an especial manner the cement which kept together the whole fabric, but the inspirer of much work which was carried to fruition by others.

In 1645, the year when Wren invented, as a boy of thirteen, a new astronomical instrument, the first meetings took place at which was sown the seed from which the Royal Society sprang. Dr. Wallis, the mathematician, Dr. Goddard, Wilkins, later Warden of Wadham, and Sir Christopher’s father, Dr. Wren, were amongst the attendants at weekly gatherings, when philosophy and especially natural science were discussed.

When Wallis, Wilkins, and Goddard went to Oxford in 1648-49, the London meetings continued, but new meetings were held also at Oxford, first in Dr. Petty’s rooms and afterwards at the apartments of Wilkins at Wadham. When Wilkins went to Trinity, Cambridge, the Oxford men enjoyed the hospitality of Robert Boyle.

The London meetings were held often at Gresham College and, when Wren was fulfilling his duties as Professor of Astronomy at the College, after his Wednesday lectures and after Rooke’s Thursday lectures. Lord Brouncker, the friend of Pepys, John Evelyn and others were frequently at the meetings, and the Royal Society took formal shape, after one of Wren’s lectures, on November 28, 1660, when Brouncker, Robert Boyle, Rooke, Wilkins and others withdrew to Wren’s private room and decided to constitute themselves formally as a college or society. It was after Wren’s next lecture on December 5, 1660, that Sir Robert Moray notified to the meeting the King’s pleasure at the constitution of the society and his promise of encouragement.

The Society of Philosophers into which the young Wren found himself plunged owed its inspiration above all to the writings of Bacon.

Bacon was not himself a man of science in the sense that Galileo or even Descartes was, for he made no observations and arrived at no discoveries in any particular branch of science. But he summed up all the Renaissance revolt against Scholasticism, and had set forth in a noble literary form a definite system of knowledge that could be opposed to the so-called Aristotelianism which hitherto had held sway over the minds of men. Bacon’s guiding principle was the appeal to experiment, for his famous “method of induction” amounts to that. The Scholastic writers worked by deduction. They laid down their premisses, they worked out the laws of formal logic by which they could draw deductions from them, and they accepted the conclusions without enquiring whether the premisses could bear the weight of the superstructure built upon them. Bacon opposed to this his dictum, “hypotheses non fingo;” the business of the man of science is to collect the facts without any preconceived theory, and to let the facts themselves reveal the law which binds them together. Actually, scientific discovery does not proceed in this way. Without a guiding hypothesis the mind is lost in a wilderness of facts, but the value of the hypothesis must be checked continually by its capacity to embrace the known facts and to predict new ones. None the less, Bacon’s method was at the time a necessary summons to experiment, and under its stimulus the young men of the day attacked the problem of the natural world about them with the enthusiasm of crusaders. For as a corollary to his method Bacon had insisted upon the necessity of studying the common arts and crafts hitherto regarded as beneath the dignity of philosophy. In the operations of the mechanic or the smelter, and in the growth of crops, were to be found the materials of science. So the new philosophers were universally curious and their curiosity about things was the note of the society in which Wren grew up and the dominant feature of his own mind until he settled down to architecture.

Wren’s scientific equipment was primarily that of a mathematician, and to this he added an inventive turn of mind, which developed first in the construction of apparatus and was afterwards so nobly turned to account in his building. As a man of science he touched everything and adorned it, but he cannot be regarded as a supreme pioneer in any particular direction, nor is his name associated with any fundamental discovery. As mathematician he was abreast of all the knowledge of the day; he contributed to the advancement of knowledge therein as in his discussions of the cycloid, but even in that particular subject his work lacks the luminous intuition displayed by Pascal. Nor did he break fresh ground and conceive new methods which afterwards developed into part of the fundamental texture of mathematics, as Wallis did with his theory of infinitesimals, or as Newton did a few years later in a larger field.

Wren’s activity at the Royal Society in the multifarious problems which its members examined must not be allowed to obscure the fact that, professionally, he was an astronomer. Gresham Professor at twenty-five, and Savilian Professor at twenty-eight, he achieved little that has survived. The world and his own nimble mind called him to an excess of enterprises. In 1662, his indulgent friend Sprat wrote, “The Vice-Chancellor [of Oxford University] did yesterday send for me to enquire where the Astronomy Professor was, and the reason of his absence so long after the beginning of term.... He most terribly told me that he took it very ill you had not all this while given him any account of what hindered you in the discharge of your office.” Sprat stoutly defended Wren and urged on the angry Vice-Chancellor that the rebuilding of St. Paul’s and the fortifying of Tangier (Wren toyed with the latter but refused it) were of greater “concernment for the benefit of Christendom” than “the drawing of lines in Sir Harry Savill’s school.” It was not until 1673, however, that Wren officially turned his back on astronomy by resigning the Savilian professorship. The chief document of his astronomical career is his inaugural Gresham lecture in 1657, of which Latin and English versions are printed in Parentalia. A manuscript lecture, De corpore Saturni ejusque phasibus Hypothesis, flits irritatingly by us as having been possessed by one William Jones, Esquire, but after that—silence. The Gresham oration was a little pompous and for the “politer genii” whom he espied in his audience.

“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.

On January 1, 1662, “Mr. Wren was requested to prosecute his design of trying by several round pasteboards their velocity in falling.” On the 8th Dr. Wren brought in a scheme of a weather-clock. On January 22 the pendulum experiment is described at length together with Lord Brouncker’s calculation of the velocity of fall, and at the same meeting it is recorded that “Dr. Wren showed his experiment of filling a vessel with water which emptied itself when filled at a certain height.”

On February 5 “Dr. Wren was desired to think of an easy way for a universal measure different from that of a pendulum.” This was a question of devising an absolute standard of length dependent upon some natural phenomenon, which finally found expression in the metre and again in a standard of length derived by physicists from the wave-length of light.

On February 12 “Dr. Wren proposed blacklead as a better means than oil for preserving the pivots of the wheels of watches and clocks from grating or wearing out.”

On March 5 “the amanuensis was ordered to attend Dr. Wren to take directions concerning the experiment of water in the long tube.” This means the setting up of a water barometer, with water in place of the mercury of Torricelli’s experiment.

On September 3, 1662, it is recorded that “it was referred to Dr. Wren to take care of making the several experiments mentioned at the last meetings concerning the aquæ salientes,” by which we are to understand the earliest experiments on the rise of liquids in capillary tubes. The record goes on to say, “The request of the Society made at the last meeting to Dr. Wren about comparing the Earl of Sandwich’s experiments was continued but it being a business of difficulty and much calculation required more time than he could yet obtain from his other employments.” None the less, a week later “Dr. Wren was reminded of promoting Mr. Rooke’s observations concerning motions of the satellites of Jupiter,” and a fortnight later still, “Dr. Wren presented some cuts done by himself in a new way of etching whereby he said he could almost as soon do a piece on a plate of glass as another could draw it with a crayon on paper.” At the same meeting, too, “Dr. Wren proposed the experiment of forcing up water in different pieces of different diameter and different altitudes ... and was desired to bring a description of this experiment at the next meeting....” On October 8 of the same year “Dr. Wren offered an experiment about the undulation of quicksilver in a crooked tube which he suggested was for the velocity of it proportional to the vibration of a pendulum. He was desired to prosecute the experiment and to give in an account of it.”

Sprat, in his History of the Royal Society, lays especial stress on a scheme of work devised by Wren in the interests of agriculture.

“The second work (the first was the Doctrine of Motion) which he has advanced, is the History of Seasons; which will be of admirable benefit to mankind, if it shall be constantly pursued, and derived down to posterity. His proposal therefore was, to comprehend a diary of wind, weather, and other conditions of the air, as to heat, cold, and weight; and also a general description of the year, whether contagious or healthful to men or beasts; with an account of epidemical diseases, of blasts, mildews, and other accidents, belonging to grain, cattle, fish, fowl, and insects.”

Nor must we forget Wren’s anatomical and surgical experiments. In his early Oxford days he devised instruments (fully described by Boyle) for making injections into the blood of a dog, which he tried very successfully (for everyone but the dog). He also skilfully removed the spleen of another dog which “in less than a fortnight grew not only well, but as sportive and wanton as before.”

Bound up in the heirloom Parentalia is a most careful drawing by Wren’s hand of the anatomy of the river eel. Instances of his versatility over the whole field of science can be multiplied almost indefinitely.

From the end of 1662 Wren’s name began to appear less frequently in the records of the Royal Society. His increasing preoccupation with architecture and, later, his journey to Paris provide the reason. But these extracts do make clear that, even when he was preoccupied with science, Wren’s energies were to some extent dissipated by the universality of his interests and his practical skill as an experimenter. They can be accepted as explaining why he did not become supreme in any one branch of science, although any loss in this direction was, perhaps, more than compensated for by the richness of the experience and the breadth of mind that he was thereby enabled to turn to the service of architecture.

Though architecture became an exacting mistress, he always kept in touch with the Royal Society and, after a period as Vice-President when he was often in the Chair, served as President in 1680. He could not give the time to experiment, but he was an effective stimulus in the organisation of scientific thought, and took an exceedingly active part in discussions which ranged from comets to the making of jessamine-scented gloves with daffodils, from Mr. Mercator’s new projection of maps to the conclusion that “all wholesome food should have oils” (which smacks of vitamines), from the structure of peat to the contrivance of an azimuth compass.

The incredible boy of Wadham days had become the tireless President at fifty, immersed in the greatest architectural practice of his century, but still the enthusiastic scientist. I find it all very astonishing.