At the end of Silver Street, which is, happily, little over a hundred yards in length, we reach an iron bridge over the Cam; its placid stream "footing slow," as Milton says (in Lycidas), and only some thirty feet in breadth. Above the bridge, however, it widens out into a broad pool, enlivened by the rush of water from the "King's Mill," beyond which the eye ranges over the open levels of "Sheep's Green." Both the mill and the bridge are amongst the oldest features of Cambridge, and the tolls payable at both were in mediaeval times a Royal monopoly. The King's agent in collecting them on this bridge (known as "The Small Bridge" in contradistinction to the more important structure beneath the Castle) was a hermit, for whose accommodation a small bridge-house and chapel were built. This curious use of hermits, as keepers of roads and bridges, was common in Cambridgeshire before the Reformation. At Silver Street bridge the river enters on its course through the enchanted ground of the "Backs," and the visitor will do well to take water at the adjoining boat-house; for the stream here forms for half a mile a byway lovely beyond words, not to be matched elsewhere in all the world; flowing, as it does, between venerable piles of academic masonry, and "trim gardens," the haunts of "retired leisure"; umbrageous, as it is, with the shade of lime, and elm, and beech, and chestnut, and weeping willow, and laburnum; spanned, as it is, by bridge after bridge, each a new revelation of exquisite design. First we find ourselves with the old red brick fabric of Queens' College on the one bank and the thicket of "Queens' Grove" on the other, joined together by a wooden bridge, attributed to Sir Isaac Newton, the Great Natural Philosopher and discoverer of the Law of Gravity. A miracle of ingenious construction is this bridge, formed of a series of mutually supporting beams requiring not a single bolt to hold them together. Such at least it was till a few years ago, when the old timbers, after two hundred years' wear, fell into decay and had to be replaced, as nearly in facsimile as modern skill could compass. A few yards further and the red brick of Queens' gives place to the white stone of King's; the proximity reminding us that the Founders of these two beautiful Colleges were husband and wife, "the Royal Saint," King Henry the Sixth, and his heroic Consort, Margaret of Anjou. Poor young things! They were but twenty-two and fifteen respectively when they began these monuments of their liberality and devotion--upon the very eve of that miserable conflict, the wars of "the rival Roses," which brought about the downfall and death of both. But their work survived them, to be completed by Royal successors; King's by Henry the Seventh, Queens' by Elizabeth Woodville, wife of Henry's rival, Edward the Fourth of York. [Illustration: _Clare Bridge._]