<p style='text-align: justify;'>Photograph of CTR Wilson's perfected cloud chamber of 1911. By 1910, Wilson realised that he might be able to image the tracks of charged particles by photographing the streams of water droplets condensing onto ions created as particles passed through the chamber. The sensitivity was such that a single charged particle could act as a condensation centre. This resulted in the superb images shown in P1917. This was the only cloud chamber Wilson ever built. Wilson was awarded the 1927 Nobel Prize in Physics for this invention.</p>