21 H Life and LetUrs of Francis Gallon 



older people, and cites a Doreetshire proverb "that no agricultural labourer 

 who is more than forty years old, can near a bat squeak." He distinj^uishes 

 between the shurjuifss of lieanng and the hearing of higli notes, and indi- 

 cates that the position of the \vhisflt> — opposite to the auricular orifice — 

 may be of inijxjrtance. 



Dalbv 'the aurist' had already ut^ed one of (Jalton's whistles for diagnosis, 

 and Galton himself had tried experiments with them on all kinds of animals 

 at the Zoological Gardens and on insects. He put one of his whistles at the 

 end of a hollow walking-stick wliich had a hit of india-iniblKM- piping under 

 the handle, brought the stick as near jus was SJife to the animal's ear, and 

 when it wjis accustomed to it, stpieezed the tube, and observed whether 

 it pricked its ears. If it did, it probably heard the whistle. Cattle and 

 ponies, much more than hoi-ses, hear high notes. If you pass through the 

 streets of a town, working the walking-stick whistle, all the littli: dugs turn 

 round, but it does not seem to liave any effect on the large ones. 



"Of all ci-eatures I have found none superior to cats in the |)ower of hearin;; shrill 



sounds. It is jierfoctly reniarkahlc what a faculty they have in this way You can nmko 



a cat, who is at a very considerable disUince, turn its ear i-ound by sounding a note that is too 

 shrill to Ik! audible by any human car." 



Galton attributes this faculty in cats to natural selection, differen- 

 tiating them so that they am hear the shrill notes of mice and other animals 

 they need to catch. Some of Galton's audience at the conference heard the 

 hign notes of his whistles, others failed to catch them at all. Among the 

 former was Alexander J. Ellis, translator of Helmholtz's lA'hre von der 

 Tonenipjindmufen, who statetl that he heard all the high notes perfectly. 

 It is clear that very useful work might be done to-day by testing the 

 meml)ei-8 of families and forming pedigrees for cjises in which there is a 

 faculty for hearing very high notes, and probably Galton's whistles would be 

 an adecpiate means of investigation. I do not rememlx^r ever seeing a fre- 

 quency curve for a large genend po^)ulation of the limit of audil)ility'. 



An addendum to the above paper on whistles was contributed to Nature' 

 by Galton in March, 1883. He notes that while his little whistle, set at '14 

 of an inch, would give about 24,000 vibrations per second if air were putted 

 through it, the vd^rations will be some 86,500 a second if hydrogen be 

 used, ueciuse the numl^er of vibrations per second is inversely proportional 

 to the square root of the specific gravity of the gas blown through, and 

 hydrogen is thirteen tinies lighter than air. Galton tested first with coal- 

 gas, the sj)ecific gravity of which is not nmch more than half that of conmion 

 air. He found that a length of "13 of the whistle gave him pei-stjnally no 

 audible note for air; but he heiird the note at •14; he could for coiil-gas 

 ^et no audible note at "24. Galton suggests that the whistle-lengths at 

 imit of audibility, being as "14 to "25, or as '56 to I, are nearly in the ratio 

 of "GO to 1, or the specific gravities. I^t if the audibility depends on the 

 period and not the square of the period, 5(3 to I should be as the sqxiare roots 



' Oalton's published data do not really provide material for such a curve (see our p. 221). 

 » Vol. xxvii, p. 491, corrected Vol. xxvni, p. 54. 



i 



