NOTE:  This effect will not be perfectly displayed in the classroom due to the fact that it is moved in on a rolling table, therefore some vibrations will affect the alignment slightly.  Since we are not making measurements we don't need perfect alignment to adequately see the desired effect.

Plug in the table and turn on the power supply which will turn on the mercury vapor lamp.  DO NOT turn on the magnet yet.  Re-align the rail with the magnet so that the pattern is seen and centered in the camera.  The rail may also need to be leveled to get the patterned centered.  (It may help to remove the camera and observe the pattern image coming directly through the etalon during the alignment/centering step).  Once the circular pattern is seen, you can adjust the camera focus and zoom to get the desired pattern size.  At this point, you may turn on the magnet and observe the change in the pattern.  Note that when you turn the magnet on, current flows in the magnet even though the pot current control is turned all the way down.  As you increase the current in the magnet, observe how the pattern changes and how the fine spitting becomes much more apparent.