Magnets (superconducting magnets H01F6/00; for separation of solid materials or fluids B03C1/00; for bench or like work-holders B23B31/28, B23Q3/00; work-holding devices B25B11/00; lifting magnets B66C1/00; ; for electric meters G01R; for relays H01H; ; for dynamo-electric machines H02K)