1.3 MEG QuickTime File.
"... a [compass] needle vibrates by gathering upon itself, because of it magnetic condition and polarity, a certain amount of the lines of force, which would otherwise traverse the space about it..."
Michael Faraday, Experimental Researches in Electricity, Volume III, New York Dover Publications, 1965.
This is how Faraday understood the oscillations of a compass in a background field.