270 



SCIENCE, 



[Vol. VIII., No. 190 



case. Generally these black films range from 7.2 

 to 14.5 units in thickness, so that from 4 to 720 

 molecules could lie side by side therein, accord- 

 ing to the view of the size of molecules adopted. 

 A very extraordinary phenomenon was the sharply 

 marked edge of the black film, a sudden and not 

 a gradual increase of thickness taking place, be- 

 tween it and the colored film. The influence of sur- 

 face tension and viscosity upon this was discussed, 

 and the important influence of these researches 

 upon the dynamical theory of liquids was in- 

 sisted upon ; the lecturer, who quoted Sir William 

 Thomson in support of his views, considering that 

 in this sharp edge there was experimental evidence, 

 first, of a minimum of surface tension; and, sec- 

 ondly, of an alteration of the nature of force in 

 play between the molecules, which had often been 

 assumed in physical investigations, but of which 

 direct evidence had hitherto been wanting. 



A day was devoted to the consideration of 

 electrical subjects from the mechanical or en- 

 gineering side. A warm discussion took place 

 upon the relative merits of electric light and min- 

 eral oil for lighthouses, the general result being, 

 that, even for lights of a low order, the electric 

 light could compete most favorably in every point, 

 as to efficiency, first cost, and cost of maintenance. 

 The balance of evidence brought forward Avas 

 unquestionably on the side of the electric light 

 as regards fog penetration. On the question of 

 secondary batteries, some remarkable evidence 

 was adduced as to the improvements in detail 

 lately effected therein, which rendered them more 

 practically permanent, and free from disintegi-a- 

 tion. The most important subject, however, was 

 that of electric safety-lamps for miners' use. Mr. 

 Swan exhibited his latest form, which fulfilled all 

 the conditions laid down two years ago for the 

 Ellis Lever prize. The lamp was self-contained, 

 and, with a current of 0.4 amperes, gave the light 

 of one candle for twelve hours : it weighed five 

 pounds and a half, and its secondary battery was 

 much more simply recharged than an ordinary 

 Davy lamp. Moreover, a most ingenious fire- 

 damp indicator, accurate to within 0.5 per cent, 

 was attached to it. Mr. Swan claimed that it was 

 more efiicient, more safe, and more economical, 

 than any miner's lamp in use. 



At the general committee meeting held Sept. 6, 

 Sir Henry Eoscoe was elected president for the 

 meeting to commence at Manchester on Aug. 31, 

 1887, and it was agreed to meet in Bath in 1888. 

 An invitation from the government of New South 

 Wales was received for forty or fifty repre- 

 sentative members of the association to be present 

 at Sydney in January, 1888, when the centenary 

 of the colony would be celebrated. It was resolved 



to entertain the invitation ; and the council was 

 empowered to accept it, if, after due inquiry, they 

 were of opinion that a sufficient number of truly 

 representative men would agree to go. 



On the night of Sept. 6 a lecture was given to 

 the whole association by Professor Eutherfurd, 

 who broached that night for the first time what 

 might be termed a ' telephonic theory ' of hearing. 

 According to it, the cochlea does not act on the 

 principle of sympathetic vibration, but the hairs 

 of all its auditory cells vibrate to every tone, just 

 as the drum of the ear does ; there is no analysis 

 of complex vibrations in the cochlea or elsewhere 

 in the peripheral mechanism of the ear ; the hair- 

 cells transform sound-vibrations into nerve-vibra- 

 tions similar in frequency and amplitude to the 

 sound-vibrations ; simple and complex vibrations 

 of nerve energy arrive in the sensory cells of the 

 brain, and there produce, not sound again, of 

 course, but the sensations of sound, the nature of 

 which depends, not upon the stimulation of dif- 

 ferent sensory cells, but on the frequency, ampli- 

 tude, and form of the vibrations coming into the 

 cells, probably through all the fibres of the audi- 

 tory nerve. On such a theory the physical cause 

 of harmony and discord is carried into the brain, 

 and the mathematical principles of acoustics find 

 an entrance into the obscure region of conscious- 

 ness. Now, if nerve energy were only electricity, 

 that theory would probably be accepted at once ; 

 but nerve motion is very sluggish when compared 

 with electricity. The lecturer for five years had 

 kept this theory back, because he felt that he had 

 no evidence of the possibility of sending a rapid 

 succession of vibrations along a nerve. It cost 

 him a good deal of thought and experimental ob- 

 servation to find the evidence he required. In 

 dealing with methods so difficult and obscure, 

 one must beware of dogmatism ; but it was the 

 duty of the scientist to frame theories which seemed 

 to explain phenomena. One might and often did 

 err in holding back a theory lest it should give 

 pain to the author of some theory which it was 

 destined to oppose, forgetting that the suggestion 

 of a new fine of thought might in some other mind 

 lead to ideas still farther in advance. Should his 

 theory of the sense of hearing find acceptance, it 

 would lead to a reconstitution of theories regard- 

 ing the other sense-organs. The lecture was suc- 

 cessfully illustrated by means of an extensive and 

 elaborate collection of apparatus and diagrams. 



The authorities of Nancy, France, have voted 

 to add 300,000 francs to the 500,000 francs already 

 appropriated by the general government, to be 

 devoted to the construction of chemical and ana- 

 tomical institutes in that city. 



