470 Life and Letters of Francis Galton 



We heard two days ago from Mrs McLennan's* sister, who says that she (M is McL.) has been 

 nearly dying but that she is now somewhat bettor. They are preparing for leaving Davos, and 

 arc inquiring for a good place to go to. I am sorry to hear that your visit of charity did little 

 good to your own self. It was very good of you to go. Ever yours, Francis Galton. 



August 12, 1880. 

 Excuse bad paper, ink, etc., our house is in the plasterers' hands. 



Dear George, The enclosed was sent to me asking me to read it and forward it to you. 

 The writer, Walter Smith, was a bracketted 2nd Wrangler some few years back and of 

 Trinity College — you would know all about him. I knew his people well, especially his father, 

 Archy Smith. 



Did I tell you that during a happy day I spent among the idiots at Earlswood I learnt 

 from the very intelligent medical director, Dr Grahame, that his inquiries about the parents 

 of the idiots quite confirmed your conclusion about cousin-marriages, and that he had said so 

 in print? 



I suggested to W. Smith that if he wished to work up the subject de novo he should get an old 

 Burke's "Peerage" and "County Families" and pick out the first hundred or so cousin-marriages, 

 also of ordinary marriages that he came across, and partly by the help of more recent editions 

 but chiefly by that of gossips about the aristocracy compare the results. If the difference was 

 not a notable one he might be at rest as to harm done by not forbidding the banns. I wonder 

 if he has a personal interest in the inquiry. What a charming episode in a novel — the 

 conscientious young Scientist collecting laborious statistics before he ventured to propose. 



We go to McLennan's to-day, to stay till Saturday afternoon at Hayes Common. 



Ever yours, Francis Galton. 

 P.S. Thanks for grouse. 



42, Rutland Gate, S.W. December 11, 1881. 



My dear George, Here are the three sets I circulated of Mental Imagery questions. They 

 were usually followed up by correspondence. 



What a wonderful application of your earth-history theory is this big tide in early 

 geological times ! I want particularly to read your account of the matter when it appears, and 

 to have your own views thereupon. It is a grand idea indeed — the grandest since the Origin 

 of Species. Have you thought over the corresponding air tidal-wave? Now, in the tropics, the 

 diurnal barometric range is (...? say * inch), what will it have been in those times? And what 

 would be the corresponding wind force? I can't understand how any thing could live on dry 

 land under such blasts. Talk of catastrophes, why, that time must have been a continual 

 series of catastrophes. Dante's Hell is nothing to it. But I had rather have the facts from 

 you than through the Astronomer Royal of Ireland. Don't of course bother to answer this, 

 but I hope we shall soon read a short article from you in Nature or somewhere on this 

 extraordinary revolution in old ideas. 



Have you too (I ask not for an answer) talked over or thought about the air flying off from 

 the earth, and notably from the moon, to somewhere else? I mean what we were talking about. 

 Lord Rayleigh seemed to think it worth considering and within range of calculation. Just now 

 I suppose you are busy up to the eyes with Tripos preparations. We look every morning in 

 the column of births in the Times for news from Horace f. Ever yours, Francis Galton. 



The Athenaeum. December 11, 1881. 



What frightful nonsense I have just despatched in a letter to you about air-tides. There 

 was conversation — I had two ideas in my head and they blundered together as in a dream, the 

 letter went and I could not correct it. 



In sober sense I should have written: Supposing height of air-tide in an imaginary 

 homogeneous atmosphere to be the same height as water-tide (Herschel says so), say 8 feet, 

 then the corresponding barom. pressure due to air-tide would be O008 inch. Under the supposed 

 ancient condition of a 216-fold height of tide this would become 216 x 0-008 = 1-728 inches, so 

 that the barometer would go up and down 1| inches in every 12 hours, which implies a constant 

 state of hurricane. F. G. 



* The wife of Donald McLennan, the writer of The Patriarchal Theory. 

 f Horace Darwin, Charles Darwin's fifth son. 



