3 66 



NATURE 



[January 9, 19 19 



no particular note is produced for a whole m 



and, therefore, not perceived for a whole second. 



But, on ill'' other hand, it is clear that we ian 

 listen to a high-pitched note for a second or for a 

 minute or for any length of time. When we are 

 hcaiing a note of 20,000 d.v. per second pitch, we are 

 almost certainly not receiving 20,000 impulse? per 

 second into the central nervous system, To take an 

 analogy from vision: when we perceive red light, we 

 are certainly not receiving anything like (395x10") 

 impulses per second, which is the "pitch" of red 

 light. If, in seeing coloured light, such an enormous 

 number of vibrations in the aether affect the retina, 

 there must be something of a very different character 

 as regards frequency, which, ascending the optic 

 nerve, so stimulates the visual centre that we see 

 coloured light. 



We have in perceptual consciousness qualitative 

 differences corresponding with objective quantitative 

 differences, an ever-present problem of psycho-physics ; 

 and no one has ever suggested that our optic nerves 

 and visual centres are dealing with impulses at many 

 millions a second. Why, then, may we not apply the 

 same reasoning to the ear? 



When we are listening to all possible tones from, 

 say, 1000 d.v. per second pitch to 40,000, may we 

 not somehow have in consciousness qualitative differ- 

 ences corresponding with objective quantitative (arith- 

 metical) differences? We cannot, apparently, be more 

 definite than this. 



In the case of the eye there is no conceivable pos- 

 sibility of an identity between the rhythm of optic- 

 nerve impulses and that of the vibrations of the 

 aether ; is it not by analogy probable that neither is 

 there anv direct correspondence between the auditory 

 nerve-impulses and the periodicity of sonorous vibra- 

 tions? D. Fraser Harris. 



Dalhousie University, Halifax, N.S., 

 November 29, 1918. 



A Mistaken Butterfly. 



Though I cannot claim any special knowledge of 

 insect behaviour, I hope you will allow me to make 

 a few remarks on "A Mistaken Butterfly" discussed 

 in Nature for September 5 and December 12, 1918. I 

 have my doubts as to whether it was the butterflies 

 or the observers who were mistaken. A butterfly 

 does not always alight on a flower, or on what it 

 supposes to be one, but appears frequently to alight 

 for rest. Now, in selecting a resting-place, it will 

 naturally select a good "taking-off " position, and the 

 knob of a hatpin and a golf ball are evidently from 

 the butterfly's point of view good "taking-off" posi- 

 tions, especially the golf ball, it being surrounded by 

 no good "taking-off" places, and its whiteness would 

 help to direct attention to it. 



A number of years ago I met two keen entomo- 

 logists in Italy who were disappointed in not suc- 

 ceeding in capturing a butterfly they particularly 

 wanted, though they had seen a number, but failed 

 to net them. As I knew where that particular 

 butterfly was likely to be found, I took my walk in 

 that direction the following day, and on returning 

 presented my friends with two specimens of the 

 butterfly. These were captured without a net, by 

 what I imagine is a well-known method. When the 

 butterfly alighted I approached it from behind, keep- 

 ing as well out of the range of its eyes as possible, and 

 moving very slowly. When within arm's reach the 

 hand was slowly stretched out, keeping it as low as 

 possible and behind the insect. When the stalking is 

 carefullv done a capture is e, nerally made, and the 

 wings, before lifting it, may be folded to prevent 

 NO. 2567, VOL. I02] 



their upper surfaces being damaged by contact will: 

 the fingers. 



Xuu iii the case of the two butterflies refei 

 mm 1 picked off a leaf of a bush, and the other 

 ed nn my shoulder. I do not think lie >. an 

 so easily picked up if they have settled on flowers, as 

 they are there on business, and are restless ami away 

 whenever they have accomplished their object. 



John Aitken. 



Ardenlea, Falkirk, December 17. 



THE FUTURE OF BRITISH MINERAL 

 RESOURCES. 



NOW that the activities of a number of Govern- 

 ment Departments, which were called into 

 existence by the exigencies of the war, are 

 happily likely to be nearing their end, we may hope 

 to see the reports of their work given to the public ; 

 it is to be desired that a mass of valuable informa- 

 tion, accumulated often at vast expense, should not 

 be relegated to the limbo of a cobwebbed official 

 pigeon-hole, but should be made generally avail- 

 able. It is scarcely to be expected that many of 

 these reports will be as valuable as that lately 

 issued by the Controller of the Department for the 

 Development of Mineral Resources in the United 

 Kingdom (Cd. 9184, price 6d. net), seeing that 

 Sir Lionel Phillips was one of the rare exceptions 

 amongst the small army of Controllers appointed 

 by the Government, inasmuch as he had a 

 thorough acquaintance with his subject before he 

 assumed control ; perhaps also that is why he did 

 not hold his office for very long. It is character- 

 istic of the attitude of the Ministry of Munitions 

 towards a courageous and capable official under 

 it, that the Minister takes special care to state 

 that he accepts no responsibility for the opinions 

 and conclusions contained in this report. 



The report consists first of a summary of the 

 conclusions arrived at by the Controller, and then 

 of a part divided into two sections, dealing with 

 statistics of production and the inferences to be 

 drawn therefrom. For the numerous valuabli 

 tables contained in this report the original must 

 necessarily be consulted, but some of the con- 

 clusions of Sir Lionel Phillips deserve both study 

 and comment. He shows clearly that the native 

 British production of non-ferrous metals falls far 

 short of our requirements in normal times, as 

 follows : — 



iciion. Consumption. 



Pon Tons 



Lead 17,000 ... 179,000 



Tin 



Zinc 

 Copper 



The tendency oi the report is to show that no 

 very great improvement in output is to be ex- 

 pected, except perhaps in a few isolated instances ; 

 it is shown that the output of non-ferrous metals 

 has been falling off continuously for the last sixty 

 years. The main causes assigned for this fact are 

 the impoverishment or exhaustion of the deposits, 

 and the increased costs of ore extraction and of 

 pumping on one hand, and fall in value of metal 

 on the other. Sir Lionel Phillips also lays stress 



