MAGNETO
'(<a href="http://www.j-archive.com/media/2007-02-21_DJ_08.jpg" target="_blank">Jon shows images of early devices on the monitor.</a>) Early electromagnets, like Joseph Henry's in 1831, were horseshoe-shaped to double the pulling power of <a href="http://www.j-archive.com/media/2007-02-21_DJ_08a.jpg" target="_blank">this</a> type of magnet'
a bar magnet