502 Life and Letters of Francis Galton
which he considers to be A. Then each of the selected group is marked with an A„ of so minute a size as to be readily overlooked. A second examiner, No. 2, who overlooks the A1 marks, proceeds in the same way, and each of his selected set is scratched with an A2. Subsequent investigation shows that:
I. a, of the balls marked A1 are truly A.
II. a2 of the balls marked A2 are truly A.
III. a, of the balls marked A1 and A2 are truly A.
Question. What is the trustworthiness, when measured on a scale of equal parts, of the three estimates defined by I, II and III1
Mem. The scale of trustworthiness is bounded, below at a zero point, of no trustworthiness
at all, when a =l000' and, above, where precision is absolute, when a= a.
42, RUTLAND GATE, S.W. May 20, 1897.
MY DEAR PROFESSOR KARL PEARSON, You were not, as I heard, at the Royal Society Soiree last night, where I had hoped to have thanked you sincerely for the book and for the exceedingly kind writing on the fly-leaf. It is one of the great pleasures left me, to know, now that I grow older and stupider, that anything I may have done has proved serviceable to others who, to misquote Tennyson, can "step from my dead self to higher things."
I was absent from London all the day-part of yesterday and have only very cursorily as yet looked through the book, but have seen enough to astonish me at its wide range and serious reasonings and at its substantial unity among apparent diversity. You must indeed have had difficulty in assigning a title to it. What an awful time to live in the 14th century must have been to most persons, with its plagues and endemic manias of flagellations, tarantellas and the like, and savage wars. No wonder that dances of death were popular. I look forward greatly to reading the two volumes properly. Very sincerely yours, FRANCIS GALTON.
GRAND HOTEL, ROYAT. August 13, 1897. 5 a.m.
DEAREST EMMA, It is ill news that I have to send. You heard that Louisa* had been ill since last Sunday, when she packed up in good, spirits and with much interest for a tour among the Dauphine mountains, beginning with the Grande Chartreuse. But it was not to be. She was seized with a severe attack of diarrhoea and vomiting during the night, a repetition of what she, I and Mme de Falbe had all had in a lesser degree. Still Dr Petit thought little of it on Monday morning, even on Tuesday morning he was not anxious, but she grew steadily worse. The bile thrown out was exceedingly disordered and I think its presence throughout the body poisoned her. She had of course discomfort at times, but was on the whole drowsy. Yesterday she was evidently sinking. I had a nurse to sit up through the night, who awoke me at 2,',- a.m. when dear Louie was dying. She passed away so imperceptibly that I could not tell when, within several minutes. Dying is often easy! I believe French formalities require very early burial, probably to-morrow, but I know nothing now. When the people are up and moving I shall hear all about necessary legal formalities, which-may take time. This is written to catch the morning post to England. You shall of course hear again very soon. I cannot yet realise my loss. The sense of it will come only too distressfully soon, when I reach my desolate home. Please tell the brothers and sisters. I am too tired to write much, having had long nursing hours. Mme de Falbe is our one friend here, but she was in bed yesterday and to-day with a slight attack of the same malady. Her maid has been very helpful. The landlady is all kindness. The nurse (a religieuse) did her best, and so did the chambermaid, they and another woman got up in the night to do the sad and necessary offices. Dear Louisa, she lies looking peaceful but worn, in the next room to where I am writing, with a door between. I have much to be thankful for in having had her society and love for so long. I know how you loved her and will sympathise with me. God bless you. Ever affectionately, FRANCIS GALTON.
Mrs Francis Galton, nee Butler.