Abstract: A completely mechanically operated microscope bridge includes rapid rough positioning, fine positioning, coarse focusing and fine focusing with an automatic locking system locking the microscope at the position set by the operator whether power is on or off. In the focusing mechanism the drive slips when the microscope hits the viewing platen or if the microscope rhomboid is caught under the cross beam or overhanging arm on the light table while being raised. A brake prevents the microscope from being manually pushed into the viewing platen. In the x and y plane movement mechanisms torque limiting clutches prevent damage to the drive mechanisms, and a slip clutch allows turning of a positioning knob without driving when the bridge reaches the end of travel.