126 



NATURE 



\yune 9, 1 88 1 



The other pohits in which I differ from Mr. Vena have been 

 mentioned in my former letters (see Nature, vol. xxiii. p. 

 578, and vol. xxiv. p. 5), and need not be here repeated. Mr. 

 Venn however labours under a serious misapprehension if he 

 thinlis that I attach any importance to the distinguishing features 

 of my method as iiure barren conceptions. Their real importance 

 lie^ in the use which I have made of them, and this use cannot 

 be faii'ly appreciated without examination of my published solu- 

 tions in the Proceedings of the London Mathematical Society, in 

 the Educational Times, and in the Philosophical Magazine. I 

 must protest against that spirit of criticism which would offer two 

 or three chipped bricks as a fair specimen of a house, a-id 

 would depreciate the lab mrs and damp the zeal of all scientific 

 workers by unduly emphasising the undeniable fact that all 

 logical and mathematical methods are, after all, mere combini 

 tions, developments, or extensions of a few simple truths which 

 are the common property of all mankind. Even Boole's " actual 

 originality," Mr. Venn tells us, though I think he tatzx^i prioi-ity , 

 "was by no means so complete as is comm >nly suppDsed and 

 asserted" (see Mr. Venn's Introduction, p. 28). According to 

 this method of criticisji we might ascribe the invention of the 

 steam-engine to the person (unfortunately unknown) who fir.-.t 

 discovered the important principle of a revolving wheel, and 

 turned it to practical account by making a wheel-barrow. 



In conclusion I must thank Mr. Venn for the compliment 

 which he kindly pays me on p. 372 of his work, but I think it 

 would read better without the parenthesis, "as he assures us is 

 the case." The " assures " is a little too strong for the simple 

 statements which I made, and which it never occurred to me 

 that any one would dream of doubting. The compliment \\ould 

 also please me more if it did not so completely ignore the 

 earliest, the most difficult, and the most important of my papers 

 in the Proceedings of the Mathematical Society, namely, that 

 which treats of the limits of multiple integrals. This part of 

 my method (which gave rise to all the succeeding developments) 

 resembles nothing, so far as I know, that has preceded it ; and 

 if Mr. Venn had f)und time to read it, the objectionable paren- 

 thesis which I have quoted \\'ould scarcely have presented itself 

 to his mind as in any way called for. Hugh McColl 



Boulogne, May 25 



Resonance of the Mouth-Cavity 



Since communicating to Mr. Sedley Taylor my recent ob- 

 servations on the cipabilities of the mouth as a resoiator, and 

 forwarded to you, with my jjermission, for publication in 

 Nature, I have made the following experiments with perfect 

 success, and believing that they will be interesting to your 

 acoustical readers I send a list of them to you, and hope you 

 will be able to find a place for its insertion in your next issue : — 



Experiment I. — While one of the overtones of a loud prime 

 was resounding in my moath another person heard it distinctly, 

 up an the ear of the latter being held near the source of 

 resonance. 



Experiment II. — While a cart — any other noisy vehicle will 

 do as well — was going along the street, I readily tested the 

 composite nature of the noise by the resonant capabilities of my 

 mouth. 



Experiment III. — I turned the water-tap on into a basin (the 

 water was running with a good force), and from the noise make 

 by the falling liquid I was able to get different sounds quite 

 easily. 



In both these latter experiments I observed, while opening 

 and closing my mouth, that the pitch rose and fell as when one 

 slides a finger up and down a vibrating fiddle-string. 



Experiment I]'. — I held down in the treble part of a har- 

 monium — with an 8- feet stop out — several consecutive keys to- 

 gether, and while the n ites were sounding which composed the 

 horrible discord, I was able to single out any of them separately 

 by the sympathetic resonance of my mouth. 



This experiment can be done equally well at the organ. 



Exfierimcnt ]'. — I held down four or five of the low keys of 

 the organ with the S-feet trumpet drawn, and the beats of the 

 overtones resounded very prominently, so that by taking two 

 contiguous ones at a time the result was like the voix celeste stop. 



Experiment J^J. — I tried several notes in the c — c octave of 

 the clarinet organ stop, and heard the regular order of partial 

 tones by resonance, but the even ones were w'eak and odd ones 

 very strong. 



Experiment VII. — I held down c' and ^'on the harmonium, 



and heard the first coincident partials beat distinctly — due to 

 equal temperament. 



Experiment VIII. — The first five partial tones of an average 

 bass voice were studied. The notes chosen far observation were 

 ^< /. S< "bi ''!>• To each note the vowels A as in hay, A as in 

 ah, E as in me, /as in high, as in oh, f/as m you, were sung. 



It was found that not only did the different vowels give 

 different qualities, but that the same vowel had a different quality 

 fir almost every one of the five notes sung. The E as in me and 

 t/ as in jo« had generally weak low overtones. The / as in 

 high, on the contrary, gave them out well. 



It will perhaps be as well to say, for the benefit of those who 

 may not have tried to get a sympathetic resonance of the mouth, 

 that success is likely to be sooner obtained by first practising the 

 mouth in goiig from the ou to the ah shape, and from the ott to 

 to the e shape. 



It is also recommended that the ears be stopped by the fingers 

 when doing these experiments, in order to lessen the possibility 

 of mistaking the direct sound for resonance. 



John Naylor 



5, West Park Terrace, Scarborough, June I 



" How to Prevent Drowning" 



I FEAR that if per^ons who cannot swim place reliance on the 

 advice given by Mr. MacCormac in your iinpre--sion of Tune 2 

 (vol. xxiv. pp. 62, loi) they will hardly succeed in sav.ng their lives 

 should they happen to fall into deep water. It is an error to 

 say that the "human frame, bulk for bulk, is hghter than 

 water," for unle-s that frame be covered with fat beyond the 

 average, it has a greater specific gravity than water. And after 

 all, a tolerably fat body is lighter, bulk for bulk, than watei 

 only by virtue of the air in its lungs, and should that air be 

 expelled by the frantic .^creams of the immersed person, he will 

 soon find, if unable to swim, that the notion of his frame being 

 specifically lighter than the water is a myth. The dead body 

 even of a tolerably fat person being destitute of air in the lungs, 

 sinks at once to the bottom in salt as in fresh water. The 

 average human being, were he to permit his body to sink as far 

 as it will, would soon find himself at the bottom of the sea or 

 river. Besides, even in the case of a person fat enough to be 

 lighter, bulk for bulk, than water, it is necessary that he should 

 assume a certain position in order that he may succeed in keep- 

 ing his nose and mouth above the water, and unless he learn 

 how to do this in the water itself I doubt if instruction on 

 dry land would ever enable him to float. We all know 

 the story of the Hibernian who, having narrowly escaped 

 drowning, vowed he would never enter the water again until 

 he had learnt to swim, but we are not told if he ever 

 qualified himself for going into the water again. To 

 try and persuade people that by attending to certain rules 

 they may get into deep water without the risk of drowning 

 is to create a false c infidence which will rather increase 

 than diminish the number of deaths by drowning. Imagine 

 a terrified person just plunged for the first time into deep water 

 trying to recall all the directions he his read about shutting his 

 lips, swallowing his breath, permitting his body to sink until it 

 shall displace as much water as equals the body's weight, tread- 

 ing the water, and so on. Why he would require, in the midst 

 of his a;ony of fear, to possess as many contradictory qualities 

 of mind as Macbeth says no man can hive. I venture to assert 

 that no one was ever saved from drowning by following such 

 directions as your correspondents here give. It should be stated 

 ill the plainest manner th.it there is no safety for a person in 

 deep water but in a knowledge of swimming. Swimming 

 should be taught to every boy and girl as a necessary branch of 

 education. It has these advantages over much that is taught in 

 schools, that it is a useful, a delightful, anl a healthful accom- 

 plishment. R. E. Dudgeon 



52, Montagu Square, W., June 3 



Dust-winds at Hankow 



During the spring of 1878 my attention was directed to 

 the dust-winds which are not of unfrequent occurrence along 

 the valley of the Yang-tse in the warm and dry seasons of 

 the year. These du^t-winds, as I observed them at Hankow, 

 had sometimes the appearance of a dense mist ; whilst at other 

 times the air seemed to be penetrated by a fine haze ; and in 

 all cases a fine and almost impalpable dust was deposited 



