Abstract: An insulated wire is wound into a cylindrical coil by being continuously introduced into an annular space between a cylindrical core and a cylindrical sleeve coaxially surrounding same above a supporting surface which is rotated about their axis at an angular velocity W, the wire being fed in at a linear speed V. A processor is programmed to vary the ratio V/W according to the relationship(V/W).sub.i =.pi.[D+2d)(a.sub.i -1)]where D is the diameter of the core, d is the wire diameter and a.sub.i is an integer representing the order number of the i.sup.th turn of a spiral path, counted from the core surface, along which the wire is laid in a succession of flat layers piled one atop the other. Each layer consists of n contiguous turns following one another in a radially outward direction in odd-numbered layers and in a radially inward direction in even-numbered layers, with decrementation or incrementation of the ratio V/W at the end of each turn.