On one end of the tube was the cathode, which emitted cathode rays. The rays would pass through two metal slits - first slit acted as the anode while the second slit was connected to the earth. the two parallel aluminium plates were connect in an electric field between the plates, used to bend the cathode rays. On the other end of the tube was a large glass sphere. Cathode rays that hit the sphere would create a fluorescent patch. THOMSON pasted a scale on the surface of the sphere to Measure the deflection of the cathode rays.