A) The Princeton MRI Experiment is a Taylor-Couette apparatus in which the end caps of the vessel have been divided in to two pairs of nested, independently rotatable end rings. B) The primary diagnostic of the fluid velocity is laser Doppler velocimetry (LDV). Radial profiles of v_θ are acquired with the diagnostic viewing the fluid from the side. In the axial orientation two components of velocity v_θ and v_r are measured. Simultaneous measurement of the two velocities gives a direct measure of the r − θ component of the Reynolds stress. Due to very low data rates, the Reynolds stress is measured primarily at one point.