Letter from [Hugh Longbourne] Callendar, Board of Education, South Kensington, London, to [Robert William Frederick] Harrison 'My dear Harrison, Would you kindly have cards sent me at the College of the titles of the papers to be read at each meeting of the [Royal Society]. with apologies for troubling you. Yours truly, H L Callendar. P.S. When is Hopkinson's paper due. I should like to get Clerk'. 7 February 1906