360 Life and Letters of Francis Galton 



I have written both to Miss Elderton and to Heron, saying nice things. The latter has sent 

 me the calculated values for the little formula ; I have tried unsuccessfully to put my point in a 

 "Note" as clearly as desirable, so that matter must stand over for the present. I will try again 

 later. I see your lectures at the Royal Institution on Albinism are announced. Sir Trevor 

 Lawrence (Pres. of the Horticultural), a great grower of orchids, has his home near here. He has 

 much to say about an albino orchid of his, but I am so weak in botanical nomenclature that 



1 am not at all sure whether I understood rightly what he told me. If you care for more, 

 sufficiently to frame questions, I could easily get answers from him. 



Lady Phillimore near Henley on Thames, the wife of the Judge, showed me a breed which 

 she thought unique (as I understood) of white ducks in a pool in her grounds. 



I must not trouble you with more than to beg you to give my heartiest Xmas greetings to 

 Mrs Pearson and your children. Ever affectionately yours, Francis Galton. 



Hampstead. Christmas Eve, December 24, 1908. 



My dear Francis Galton, I saw Heron yesterday. He has delayed his journey north- 

 ward in order to work now, and take a few days off at the beginning of next term. The University 

 of St Andrews has asked him to give four lectures, and I thought he had better do it and spread 

 the light there, as Macdonell has done at Aberdeen. He seemed to appreciate your kind letter 

 very much. We arranged a course of Lectures at University College of which I send the rough 

 draft. I think it ought to do well. We tried to get the subject into 5 or 6 but had to give up 

 the idea. Please comment on it. Did you hear whether the white ducks at Henley were true 

 albinos with red reflex in their eyes? 



The Treasury of Human Inheritance progresses, and I think it ought to be out by January. 

 The great difficulty is to get all the material into the same "format." Each man makes his 

 pedigrees, his notes and his bibliography in a different way. But after the first number appears 

 we shall have a more concrete form for future contributors to work by. You take for example 

 "Deaf-Mutism" or "Tuberculosis," and nobody so far has made a bibliography of papers dealing 

 with heredity in these subjects. All sorts of pedigrees have been coming in, and I think when 

 the first few parts are out, we shall have a constant flow. The heredity inquiry is everywhere 

 in the air now. 



I hope this cold turn will not be too bitter for you. I am much better, but still tender in 

 the back, and I can't get up or down easily. I must say I like for working purposes a good high 

 temperature. With the best wishes for the New Year for both Miss Biggs and yourself, 



I am, Yours affectionately, Karl Pearson. 



Mrs Weldon has been working for more than a fortnight in the Laboratory over the mice 

 skins. It is a big business, but we shall get it through some day. 



About your problem in correlated variables, I think you are correct if A, B, C, D, which 



are causes of X are not correlated among themselves, for the reduction of variability <r is then 

 indicated by a standard-deviation 



= ir\/l-r I '' ! -r, ! -» , s s -.... 



But if they are correlated, I am less certain about your view. For example for two causes 



2 and 3 we have 



'f- 



a + "*"ia'"s»**»i 



and r a contributes to this reduction by the term 2r, 2 , r 23 , r 31 , as well as by — r» 8 . Thus I don't feel 

 quite clear about your view when the causes are correlated together. 



Meadow Cottage, Brockham Green, Betchworth. December 30, 1908. 



My dear Karl Pearson, A sharp attack of asthma which has departed this morning as 

 suddenly as it came on sent me to bed with three warm bottles, unfit to do anything but sleep. 

 So excuse delay in answering. 



The programme of lectures seems excellently devised, being good in itself and bringing out the 

 subjects of which the lecturers can speak with authority. Hereafter one wishes for lectures on 

 some such subjects as " Effects of small social changes in promoting the birth-rate of capable or 



