Architecture: Evolution of a Cambridge species: Peter Dormer finds Darwin College's new study centre offers a scholarly view of the world

Darwin College, Cambridge, is so self-effacing you barely notice it from the street. When you enter you feel you are intruding on a home, and the least clubbable of men can sense its congenial atmosphere. It was this sense of ease that Jeremy Dixon and Edward Jones were keen to capture in their new building for the college, the Darwin Study Centre.

Architecturally, Darwin College (founded in 1964 exclusively for postgraduate research) is long and stringy. At its core is Sir Charles Darwin's old home, Newnham Grange, a former granary, and some newer, purpose-designed buildings. Sir Charles was the grandson of Charles Darwin of evolution fame. On one side it is bounded by the tourist-filled Silver Street. The college has turned its back to the street, and works and lives with its face towards a lush watery landscape of the River Cam, a millpool and delightful semi-wild gardens.

The centre lies at the far end of the college in a narrow rectangle between Silver Street and the Cam millpool. The two-storey design has the proportions of a small passenger steamer and provides computing services and 24- hour access for 70 scholars.

Jeremy Dixon, who led the design team, says: 'We knew this building was not a great formal library but a place for different kinds of study. You can work overlooking the river, or sitting out on the balcony, or in the computer rooms. You can have discussions around large tables or read quietly on settees.'

The computer rooms are on the ground floor, while the main reading room extends like a series of decks on a boat. From certain viewpoints you can see the whole anatomy of the interior in a single vista. There are also plenty of windows and doors that open out over the water.

The geometry of the interior is intriguing. The wall facing Silver Street is curved, the walls to the river side are straight. Consequently, the geometry of the roof is especially interesting because its rafters have to reconcile the straight line with the curve and the result is a gentle, three-dimensional curved plane.

Both outside and inside the dominant material is English oak. The rafters are exposed, but bedded in a skin of plywood to stop them curling. The structural posts and beams are foot-square lengths of green oak. The window and door frames and the shelving are in oak as are the substantial but elegant tables designed and made by Joseph Dixon, Jeremy's brother. This building is one continuous piece of furniture.

The surfaces of the big posts and beams are splitting into long, irregular fissures because they are still comparatively wet. These dramatic developments were expected and add to the texture and the character of the place. The structure is held together by stainless steel bolts, and as the building settles down these will be tightened by a man with a spanner.

Very few contemporary architects in Britain have made substantial structures in wood, and Ove Arup, the engineers on this project, are monitoring the building carefully. Ove Arup, whose triumphs include the Sydney Opera House and Paris's Pompidou Centre, is famous for innovative engineering and it is quite probable that this relatively humble building will have a greater influence than its size appears to warrant.

The centre feels as if it has been handmade. Jeremy Dixon usually makes his own architectural models as a means of resolving details and, as he puts it, 'settling my mind'. But for all its craft this remains a modern building. The sharp-eyed cultural critic can spot several influences at work, including some references to contemporary abstract sculpture.

For example, the three computer rooms are big, self-contained 'white boxes', designed and placed in such a manner that they could be air-lifted from Cambridge to London's Tate Galley, where they would sit quite naturally amid the minimalist sculptures of the late 20th-century collection.

The underlying intelligence of Dixon and Jones's new building is in its plan. First, the college extends along a central corridor that is like a footpath which changes in texture and character as it threads through the different buildings. The architects have seen to it that the centre continues the 'footpath' idea. You can walk through and around the centre and back along the college's main thoroughfare. Second, the design fits its site organically. This makes it good urban design because, unlike so many new buildings that squash themselves down with no regard to the street plan or the pattern of adjacent streets and buildings, this one takes its shape from the site.

Yet what lingers in the mind is that the new building captures the college's sense of detachment and its watchfulness. Amid the many well-lit spaces in the centre, there are a handful of quiet, burrow-like places where people may hide. One of these is a niche on the second foor, in which is a settee that faces a small window overlooking Silver Street. The window holds an angled mirror that allows you to watch the goings-on in the road without being watched yourself, an unusual but arresting visual metaphor of the scholar's view of the world.

(Photograph omitted)