When Johnny is photographing the papers that Professor Dohlmann has given him, he takes the normal bulb out of his Anglepoise desk lamp and puts in a brighter bulb. When he turns on the light, the new pattern of light does not match that from the lamp; instead it appears that a light in the ceiling, with a broader beam, has been turned on. When Johnny then moves the Anglepoise closer to the papers, the light does not change as it should do if the light were coming from that lamp.