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514   Life and Letters of Francis Galton

Sir W. Turner and myself had been referred to the original examiners and the whole matter on eceiving their report was discussed by the Senate, who sent all the material to myself and I presume to Sir W. Turner also, asking certain questions., (They don't want to hear in reply before October.) I thereupon drafted what I had to say and, on returning to town last night on the way to Dover), posted it to Sir W. Turner. Half an hour after this was done, your letter arrived ! !

About the reaction time idea*; I send the only account on which I can lay my hand of the pendulum apparatus that I used regularly at South Kensington, and which Groves of 79 (1), I3olsover St made for me. We called it, from its shape, the "A" machine. The jar of sudden stoppage is there prevented by nipping a thread kept parallel to the rod of the pendulum by an elastic band. For your case, I should propose a heavy frame for a' compound pendulum. The working part being threads with attached weights, whose periods of oscillation are a little shorter than that of the framework,' so that for all the useful part of the oscillating they, should never leave the frame. The frame should retard them. The nipping would be either by parallel-rule fashion, one pair of them for each string pushed separately, one pusher to each person, or by a vertical arrangenient on some simple double-lever, pianoforte-key, plan. I find; it most difficult to draw what I mean intelligibly, but it appears to work out quite simply and to require no

skilled workmanship. You will know the formula for graduations. I have forgotten' all about it, except that I got, hold of some useful tables of Elliptic Functions to calculate them by. Please let me have my printed paper back as I have hardly any copies left.

I am writing at a strange club, .which we are handed over while the Athenaeumisi.nthebuilders' hands. When I go home I' will send you a copy of the Royal Commission on Horsebreeding Report, on which I have written a Report for Dover. Also I have (probably) a little probability paper there, verysimplebutratherpretty' and which (I think) may he practically useful. It was only sent in three or   four days ago, and may be crowded out.

I heartily hope you are strong and well again. I have been first for three weeks at Royat in France and then for two weeks in Switzerland, which were marvellously health giving. Yours Very sincerely, FRANCIS GALTON.

42, RUTLAND GATE, S.W. October 22, 1899.

DEAR PROFESSOR_ KARL PEARSON,_ I cannot suggest anything useful in respect to your paper (which I return), though if you were about to write afresh I should have been inclined to wish the "Logic of Chance" could be more developed. What a difficult subject it is to treat otherwise than technically!' As to the forthcoming lecture at Leeds, let me suggest a diagram- such as the enclosed; (see both sides of the paper). ;= It would take people' from abstractions down to realities. Also the topic of "nearness of relationship" would interest everybody. To show it off, the string might end in a little longish bag or bucket, into which the tip of the pointer could be slipped. You could then work the string' high above your head and all the audience would see it. You will have a very intelligent audience at Leeds, judging' from what I saw there some time ago. Very sincerely, FRANCIS GALTON.

* See our Vol. u, pp. 219-220. We have one of Galton's old Reaction Time pendula in the Calton Laboratory, which I purchased since his death from an instrument maker. t A very rough model of a genometer : see Vol. I,,A, p. 30 and Plate I.

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