June lo, 1880] 



NATURE 



139 



measured, those due to thermal effects are practically instan- 

 taneous, and therefore affect simultaneously the whole length of 

 tlie wire. 



Note. — De la Rive, in 1S43 (z^'ii' "Electricity," vol. i. p. 

 304), observed that an iron wire emitted sounds when rapid 

 discontinuous currents were passed through it ; but he attributed 

 the effect to magnetism, for he failed to obtain the same effect 

 in non-magnetic wires like platinum or silver, 



Graham Bell found, in 1S74, that a simple helix without an 

 iron core emitted sounds, and (in 1S76) that very distinct sounds 

 proceed from straight pieces of iron, steel, retort carbon, and 

 plumbago, when conveying currents. 



Prof. Hughes showed that his microphone was reversible, that 

 is, that it could receive as well as transmit sonorous vibrations. 



Mr. Weisendanger (Tdegrap/tic Journal, October i, 187S) 

 reproduced sounds on a microphonic receiver which he called a 

 thermDphone, and attributed the effect to its true cause, viz., the 

 expansion of bodies under the influence of heat, which, in fact, 

 is the explanation of all microphone receivers. 



Ader reproduced speech by the vibrations of a wire conveying 

 currents of electricity, but he found that only magnetic metals 

 w ere effective, and therefore, like De la Rive, he attributed the 

 result to magnetic agencies {vide Count du Moncel, Telegraphic 

 Journal, March I, 1S79). 



These and many other sonorous effects of currents on wires 

 may be really due to such heat-effects as I have described. 



Chemical Society, May 20.— Prof. H. E. Roscoe, presi- 

 dent, in the chair. — The first paper was entitled, " On the 

 Action of Air upon Peaty Water," by Miss Lucy Halcrow and Dr. 

 Frankland. In consequence of the statements of Dr. Tidy in 

 his paper on river-water, as to the rapid oxidation of peaty 

 matter in running water, the authors have studied upon an ex- 

 perimental-scale the action of exceptionally strong peaty water 

 upon atmospheric air. The peaty water was exposed to air and 

 light with and without agitation ; the organic matter in the water 

 and the oxygen in the inclosed air were determined before and 

 after each experiment. It was found that minute quantities of 

 oxygen were absorbed by the peaty water, but even when some 

 water was shaken for ten and a half hours in a bottle fixed on 

 the connecting-rod of a steam-engine making 100 strokes per 

 minute, only 2^ per cent, of the organic matter was oxidised, 

 assuming that all the oxygen taken up was employed in the 

 oxidation of organic matter. The authors therefore conclude that 

 if peaty matter .is oxidised the process tal;es place with extreme 

 slowness. — Dr. Frankland then read a paper on the spontaneous 

 oxidation of organic matter. This was practically a criticism 

 of the conclusions drawn by Prof. Tidy in his paper alluded to 

 above. The author first referred to the belief so prevalent 

 twelve years ago that water polluted with sewage quickly regains 

 its original purity by spontaneous oxidation, and explained how 

 this belief was upset by the quantitative evidence obtained by 

 the Second Rivers Pollntion Commissioners in 186S. He then 

 criticised the results of Prof. Tidy, and poijited out some grave 

 inconsistencies therein. Thus the Shannon, after flowing twenty- 

 three miles through Loch Derg, has its organic elements dimin- 

 ished about 18 per cent., whilst the next flow of a mile effects a 

 diminution of 38 per cent. A sample taken four miles lower 

 down showed an increase of 75 per cent., &c. These inconsis- 

 tencies could only be explained by want of care in taking and 

 securing an average sample of the river at the different points. 

 The artificial purification of mixtures of sewage and water 

 effected by Prof Tidy by running water through a series of 

 shallow troughs was then considered, and the chief cause of the 

 diminution of organic carbon and nitrogen attributed to the 

 decomposition of the urea into ammonium carbonate. The 

 author concludes that there is no evidence whatever of the de- 

 struction by oxidation of the dead organic matter of sewage by 

 a flow of a dozen miles or so in a river, still less is there any 

 ground for assuming that the organised or living matter of 

 sewage is destroyed under like circumstances. The paper con- 

 cludes with some statistics as to the effect of the water-supply 

 oa the spread of epidemics of cholera, &c. Prof. Huxley 

 pointed out that all diseases which are caused by so-called germs 

 are caused by bodies of the nature of bacteria, and that these 

 organisms were plants, and were therefore extremely unlikely to 

 be oxidised or destroyed by endosmose, as suggested by Prof. 

 Tidy, and that it was quite conceivable that a w ater containing 

 such bodies might be perfectly pure from a chemical point of 

 view, and yet be as deadly as prussic acid. Prof. Tidy, in 

 reply, pointed to the statistics of the last ten years, which proved 



that many towns which derived their water-supply from river- 

 water which had been polluted with sewage were as free from 

 fever, &c., as other towns supplied by deep-well water. 



Physical Society, May 22. — The annual holiday meeting of 

 this Society was htld at Cambridge. On arrival there the party 

 partook of luncheon in a hall of St. John's College, which had 

 been kindly arranged for the purpo:e by the College authorities. 

 Prof. W. G. Adams occupied the chair, and Mr. Warien De la 

 Rue proposed a vote of thanks to the Master and Senior Fellows 

 of the College for providing the hall. The vote was heartily 

 accorded by the members, and after some remarks from Prof. 

 Adams the party proceeded to the Cavendish Laboratory, where 

 Lord Rayleigh, as vice-president of the Society, presided. The 

 routine business of the meeting being waived. Lord Rayleigh 

 described a plan for limiting the slit of a telescope so as to alter 

 the angular interval with which it can deal. The interval is 

 measured by means of a grating formed by winding a fine wire 

 round two parallel screws of very fine thread. — Mr. Shaw ex- 

 hibited a modification of Veinholdt's apparatus for di-tiUing 

 mercury, by which a kilogram of mercury can be distilled per 

 hour. — Mr. Sydney Taylor exhibited a device for showing the 

 motion of the particles of water in the transmission of a surface- 

 wave. Sixteen disks were arranged in single file, each having a 

 \Ahite spot on its face, and on turning a handle the disks rotated 

 so that the spots, which represented particles of water, moved 

 so as to present a wave-motion to the eye. Mr. Taylor also 

 showed a manometric flame apparatus for exhibiiing to the eye 

 the difference of phase between two musical notes. This con- 

 sisted in t«o bent tubes, into which the notes were sounded, 

 and capable of being lengthened or shortened liy hand like the 

 pipes of a trombone. Opposite the ends of each of these tubes a 

 sensitive flame was placed, and a rotating mirror showed the dis- 

 turbance produced in the flames by the two different notes. A third 

 flame exhibited the joint effect of the two note--. When the tubes 

 were silent, the images of the flames on the revolving mirror were 

 seen as plane bands ; but when notes w ere sounder! into the tubes 

 they became serrated, and the serrations were like or unlike accord- 

 ing as the phases of the notes were like or unlike. — Mr. Poynting 

 exhibited a plan for altering the plane of polarisation of the two 

 halves of a pencil of rays from the polariser, so ihat half the 

 field may be made to a| ipear dark when the other is bright, or 

 both of equal brightness, at will. — Mr. Glazebrook de-cribed a 

 method of meauring the rotation of the plane of polari-ati^in of 

 light by means of two spectra giving dark lines made to coin- 

 cide. — Lord Rayleigh descriiied a plan for dem"n Irating that 

 yellow colour can be formed by combining red and b ue together. 

 He mixes a red solution of chromate of potash with a tilue solu- 

 tion of litmus, and on pouring it into a glass cell of a certain 

 thickness, the light transmitted through it is seen be yellow. 

 Plates of glass coated with gelatin impregnate with litmus 

 and gelatin impregnated wiih chromate of p ■ h and placed 

 side by side also transmit yellow light. Lord Rayleigh finds, 

 however, that the eyes f different persons vary c<insider- 

 ably in their power of appreciating the tinge of the transmitted 

 yellowy one deeming it greenish, another reddi-h, \\h>le a 

 third considers it pure yellow. This peculiarity i- not to be con- 

 founded with " colour-blindness," since all three pers-nis w. uld 

 distinguish the red and green components accurately. Lord 

 Rayleigh also exhibited a colour-box based on the Newtonian 

 principle, first carried out by the late Prof. Clerk Max > ell, but 

 of a small size. — Sir W. Thomson then proposed a vote 'if thanks 

 to Lord Rayleigh, which was seconded by Prof. W. G. .^dams, 

 and the meeting then dispersed to examine the apparatus and 

 appointments of the Cavendish Laboratory. 



Meteorological Society, May 19. — Mr. G. J. Symons, 

 F.R. S., president, in the chair. — Messrs. T. H. l-,.lm rnds, F. 

 Ekless, A. H. Taylor, and T. Turner were elected Fellows of 

 the Society.— The following papers were read : — Viriati ms in 

 the barometric weight of the lower atmospheric -'nita 1 India, 

 by Prof. E. Douglas Archibald, M.A., F.M..->. — A s etch of 

 the winds and weather experienced in the North Ail 'uiic between 

 lats. 30° and 50° during February and March, 18S0, by Charles 

 Harding, F.M.S. The period e.iPiraced in thi p per includes 

 the time during which H.M.S. Atalanta was on her h nueward 

 passage, as she left Bermuda on January 31. Kr..i:i the data 

 collected it is shown that a gale -lew in the Allan i>- every day 

 throughout the two months, excepiing on Februa y 21 ;ii.d 24 to 

 27. With especial reference tn H.M.S. Aialnnti n appears 

 probable that she would not have met with any . xvcpiionally 



