I recently discovered Barlow's Wheel and had to share it with you. It reminds me so much of Ed's experimenting with U shape magnets.
And to further add, Peter Barlow (born 1776) published mathematical books that were regularly reprinted until 1965 , when computers rendered them obsolete.
He made an important contribution to astronomy by inventing the Barlow Lens. Peter Barlow was awarded a medal for correcting a deviation in ship mounted compasses caused by iron in the hull of these ships. Also see Balrow's Law also see Samuel Hunter Cristie.
Barlow made several contributions to the theory of the strength of materials.
Barlow's Wheel is the name given to an early demonstration of a homopolar motor, designed and built by Englishmathematician and physicist, Peter Barlow in 1822
These images of 40 um x 25 um in size were obtained by sequential MFM scans after each current pulse. The motion of the walls is best seen by noting the relative displacement with respect to the fixed topographical defects (white dots). The displacement of Bloch walls as far as 200 um along the strip was observed. The direction of domain wall motion was in the same direction with the electron flow, i.e. opposite to the current direction. The displacement per pulse was dependent on the sample thickness and current density. In general, wall displacement occurs when a critical current density on the order of 1011A/m2 is reached. This experiment clearly demonstrate the feasibility of using short current pulses as control signals to alter magnetization of a specific area of the surface.
Scientists from NASA's Space Sciences Laboratory have made them visible as "animated photographs," using sound-controlled CGI and 3D compositing. It makes the fields, as explained by the scientists, dance in an absolutely gorgeous movie called Magnetic Movie. You don't want to miss this one, which is the coolest video that you'll see all week, guaranteed. You can't argue with a combo of beautiful effects and amazing science.