406 



Life and Letters of Francis Galton 



modulus) is formed on A' B'. Now I open the trap doors, successively; the shot in each vertical 

 compartment rushes down and forms its own exponic hillock, and we have already seen what 



^ £ 



— B 



the sum of them will be. The ratio of the moduli of these heaps is self-evident (they vary as 

 the square root of the indices which vary directly as the length of passage of the shot). For 



* , * i 



my Royal Institute lecture, I shall simply go into generalities to show what Reversion, etc., 

 mean and how a law is possible, and shall hang up the formulae, but not speak a word about 

 them. Affectionately yours, Francis Galton. 



To George Darwin, Esq. 



The substance of this letter appears in Galton's R. I. Lecture of Feb. 9, 



1877: see Vol. m A , pp. 6-11. 



42, Rutland Gate, S.W. July 14, 1877. 



Dear Stokes*, With reference to our land meteorology, would you kindly consider 

 and advise on the following point (which notwithstanding first appearances really falls within 

 that branch). It is, what form of mechanical indication or registration would best convey 

 "sea-disturbance"? I presume what is wanted the most is some idea of the shipwrecking or 



* Later Sir George G. Stokes. 



