We consider the question of when is the closed manifold obtained by
elementary surgery on an n-knot Seifert fibred over a 2-orbifold. After some
observations on the classical case, we concentrate on the cases n=2 and 3. We
have found a new family of 2-knots with torsion-free, solvable group,
overlooked in earlier work. We know of no higher dimensional examples.Comment: New co-author, stronger restrictions on possible Seifert bases. Final
section on 3-knots reduced to a paragraph, as a lemma was misused in the
original version. Version 3; minor improvements to first paragraph and
notatio
