A.C. losses of superconducting Nb-Ti alloy wires were measured by electrical method with alternating electrical current through wires. The losses were measured on various diameter of wires which were chemically or mechanically thined, and it was found that there were no size effects.
The losses were measured under the external parallel D.C. magnetic field, and those of commercial fine wires were also investigated. We computed the loss of multi cores wire, form the results obtained from single core wires and compared it with the experimental resuls of fine multi cores wires.
The effects of chemical etching and mechanical drawing on the losses are considered in the metallurgical points of view. The losses of Nb-Ti wires in the region of low magnetic field seem to fit Yasukochi's model.