Copy letter from William Bate Hardy to Professor W Bateson FRS 'At the meeting of the Soiree Committee it was decided that no organised endeavour should be made to obtain exhibits for the reception on May 13th, but if exhibits od a suitable character presented themselves they would be welcome. Hartridge, of King's showed me a short while ago some very interesting experiments on light filters, and it stuck me at the time that they would make a very interesting exhibit.' 22 April 1915