Letter from L F [Lewis Fry] Richardson, c/o The Sunbeam Lamp Co., Park Road, Gateshead on Tyne, to Sir Joseph Larmor Richardson has considered their conversation about his method and he can see there are cases when it would not work. These are rare, but can be recognised, and he explains when they will occur, referring to his appendix. He summarises his longer explanation by stating that the process will work except when the finite difference integral is infinite; or when the unifying factor I is infinite anywhere. He concludes by stating that he has gone through his manuscript to make it more compact. 14 January 1910