A short two miles along this road brings us to the porticoed front and white domes of the University Observatory, erected in 1822. More than a century earlier its embryo had been set up on the summit of the Great Gate Tower at Trinity College, for the benefit of Sir Isaac Newton; but this seems to have been little used after the death of that greatest of scientists. Even after the new Observatory was set up a certain lack of keenness pervaded its work. Thus it came about that Cambridge and England lost the glory of the discovery of Neptune, the most distant planet of our Solar System.
For more than a decade the irregularities in the motion of Uranus (itself not long discovered) had suggested to astronomers that there must be another planet exterior to it, when, in 1841, John Couch Adams, then only an undergraduate of St. John's College, set himself to grapple with the arduous task of finding by analytical computation the orbit and place of this supposititious body. So stupendous were the difficulties that when, after four years of concentrated effort, he submitted his results to the Astronomer Royal, begging that the planet might be looked for in a certain spot (where we now know that it actually was visible at the time), his suggestion received very incredulous acceptance. Was it likely that a mere youth should have solved this gigantic problem?
That very autumn of 1845 another young man, quite independently, devoted himself to the same quest, the brilliant French mathematician Leverrier. He, in the following summer, published the results he had so far attained. Adams had never published; but these new results so strikingly agreed with his that the Astronomer Royal's incredulity gave way, and he desired that search should be made with the great equatorial telescope, then newly erected at Cambridge through the generosity of the Duke of Northumberland.
His injunctions were carried out; but the lack of a trustworthy star map made the work long. And it was made longer by lack of promptitude. The minute celestial object (only equal to a star of the eighth magnitude) had been actually seen, but further observations were needed to establish the fact that it was indeed a planet moving amongst the stars around it. And these observations were delayed at the crucial point by the observers adjourning for a cup of tea! When they returned the sky had clouded over and no favourable night occurred for many evenings after. Meanwhile Leverrier had called in the aid of the Berlin Observatory; where there did exist a good star map, and also the eagerness so sadly lacking here at Cambridge. The very day his letter was received (23rd September, 1846), the great Berlin telescope was directed to the spot which he indicated,—and there was the planet.
The story goes that when the tidings of this overthrow of hope reached Cambridge, and were reported to the Fellows of Trinity as they sat at dinner in their Hall, it was as if a thunderbolt had fallen amongst them:
"And all talk died, as in a grove all song
Beneath the shadow of some bird of prey;
Then a long silence came upon the Hall,"
broken at last by Adam Sedgwick, the venerable Professor of Geology, who solemnly raised his clenched fist and brought it down upon the High Table, not with violence but with a concentrated tension of indignation, saying slowly, with an equal solemnity: "Confound their lymphatic souls."[181] As for the Observatory, the blow thoroughly roused it up; and ever since it has remained, both in material and moral equipment, amongst the foremost of the great Observatories of the world, where solid and useful work is continuously being done, while up-to-date instruments, methods, and records are never to seek. On one evening of each week during term time any member of the University may see the practical working of the place, and bring friends with him.
A mile further we reach the foot of the chalk slope which bounds the Cam valley. At this point lanes diverge to the right and left. The latter almost immediately brings us to Coton, a tiny village with a tiny, but most picturesque, fourteenth century church, having a (restored) Norman chancel, a pretty spire, and a yet prettier south doorway. There is, too, a massive rood screen, and a curious "palimpsest" Table of Commandments, the original sixteenth century lettering showing beneath repainted characters of the seventeenth century. Altogether the place is well worth the slight divergence needed to visit it, more especially as the lane between it and our road gives a view of Cambridge almost comparable to the prospect of
"That sweet City, with her dreaming spires"
which the Cumnor slopes (as Matthew Arnold sings) provide for Oxonians. Coton can also be reached from Cambridge by a delightful field path beneath overhanging oaks, which runs straight from Garret Hostel Bridge. Coton spire (as has been already mentioned) is the "objective" of the Trinity avenue, though the view has long been closed out by the growth of the branches.