3i6 



SCIENCE. 



THE TELEPHONIC RECEIVER. 



Mr. Preece has presented to the Royal Society the result 

 of his investigations upon radiophony. They relate to the 

 phenomena produced by the action of intermittent rays 

 upon discs and vases of different substances. Confirming 

 and pursuing the investigations of Mercadier in France, 

 and of Tyndall, he has come to the conclusion that the 

 sounds produced under these conditions aie due to calor- 

 ific effects, and not to light. 



Caoutchouc and ebionite (hardened caoutchouc), are ab- 

 solutely opaque, but they act as diathermies or tranparen- 

 cies for calorific rays ; the radiating heat can act through 

 a screen of these materials. 



It has been proved by delicate experiments, that six vi- 

 brations or more can be produced during a second, by the 

 intermittent action of the heat, producing a dilitation of the 

 disc's mass. The phenomena, therefore, produced by Bell 

 and Tainter are not due to an absorption of heat, changing 

 the volume of the affected substance. 



Mr. Preece made use of a specially constructed chamber 

 and is convinced that the sounds are produced by the con- 

 tained air, and not by the discs or surfaces of the chamber. 

 In it is placed a mechanism which recalls that by which the 

 " moulinet " of Crook's radiometre is moved under the in- 

 fluence of the heat. 



He has proved, finally, that the absorbing for the heat of 

 the gas, contained in the chamber experimented on, influ- 

 ences the production of the sounds. These experiments 

 have been repeated upon bottles blackened with camphor 

 smoke, both on their exterior and interior surfaces. 



Mr. Preece has thus been led to think that a wire of pla- 

 tinum, traversed by an intermittent current, can become a 

 source capable of producing on suitable walls calorific rays, 

 which have the power to cause sounds through the heating 

 of the gas on contact with these walls. 



The experiment was crowned with success: it was made 

 at first by sending currents into a spiral of platinum by 

 means of a stop-wheel turned with the hand, and when a 

 good microphone was substituted a reproduction of the 

 wood was effected. 



Thus has been realized a receptive telephone founded 

 upon an entirely new principle. — (La Nature). 



ALTERATION OF MILK. 



M. Fauvel, in the capacity of chemist to the munxipal 

 laboratory of Paris, has discovered that the milk em- 

 ployed for babes often undergoes an alteration which has 

 hitherto been unsuspected. In his investigations he has 

 noted the presence of cryptogamic vegetations. These are 

 found in the tubes of glass and caoutchouc, which enter into 

 the construction of the small feeding apparatus, especially 

 so in the swelling of the rubber which the infant sucks. 

 The new microphite can be easily cultivated in whey, and 

 the author has thus observed the various stages of its devel- 

 opment. This, however, is but the first of M. Fauvel's in- 

 tended investigations. This discovery is important from a 

 hygienic point of view. These observations were confirmed 

 by the fact that twenty-eight out of thirty-one cases pre- 

 sented these symptoms. (La Nature!) 



NOTES. 



Fire Balls. — There are many persons who persist in 

 their statement that fire-balls exist only in imagination ; 

 but here is the authentic statement of Henry O. Forbes, 

 who, in a letter to Nature thus describes the phenom- 

 enon. 



" I was standing in a window on the second floor of 

 the Hotel Braganza (in Lisbon), which stands close to 

 and high above the Tagus, and had an unbroken View of 

 the river. There occurred a flash followed by an instant- 

 aneous crash, but the tail of the flash, however, gave ori- 

 gin to two balls, which descended separately and not far 

 apart, towards the river, and when quite close to, or in 

 contact with the water, burst in rapid sequence, with ex- 

 plosions which might have been the crack of doom." 



Phosphorescence.— Mr. W. Crookes, after submit- 

 ting the action of precipitated aluminum to the action of 

 electric discharges in a Geissler tube, announces that a 

 phosphorescence similar to that obtained from the ruby 

 was developed. This is, evidently, the reproduction of 

 the phenomena obtained, a long while ago, by M. Edw. 

 Becquerel by means of the solar light. Mr. Crookes, in- 

 deed, adds that the aluminum, if sufficiently electrified, 

 passes from an amorphous state into a crystalline struc- 

 ture, a fact quite credible, and that it assumes at the same 

 time a rose shade kindred to that of the natural ruby, a 

 tint very difficult to understand. 



Effects of Temperature upon Magnetism.— 

 Mr. John Trowbridge has just completed the following ex- 

 periment in the physical laboratory of Harvard University. 

 He submitted a bar of iron to a great cold of 6o° cent, 

 below zero, obtained by evaporating CO 2 . He proved 

 that the decrease of magnetism, suspected by Wiedeman, 

 if the bar be at a lower temperature than that allowing 

 magnetic impregnation, is indeed a demonstrated phy- 

 sical fact. The bar, which had been magnetized at 20 

 C. below zero, had lost almost % of its magnetism after 47 

 minutes of exposure to this cold. He also observed that, by 

 keeping a bar of steel for a certain time at a temperature 

 of 20 cent., 50 per cent of its primitive magnetism was re- 

 stored. 



Preece on Faure's Battery.— Mr. Preece, the 

 electrician, is not favorable to Mr. Faure's battery. He 

 remarks that although it possessed considerable force its 

 resistance was very feeble and it could therefore give a 

 powerful current. He dwells especially upon " time " as 

 a factor in electric experiments. A strong current of one 

 minute duration can be readily obtained, but for pur- 

 poses of lighting, something more durable is needed. It 

 is a pretty thing, but for to-day it is not practical. 



The Aurora Borealis.— The idea that the Aurora 

 Borealis gave forth a distinctly audible sound was hitherto 

 regarded as absurd. Physicists, however, are beginning 

 to acknowledge it as a fact. " Nature," of London 

 has a few letters on the subject. There seems to be two 

 opinions as regards the nature of the sound produced. 

 One party pretends that the noise is analogous to the 

 rustling of silk, the other party compares it to the sound 

 of crackling flames. The question however will shortly 

 be solved by means of baloon ascensions that are now 

 being made. 



Action of Light upon Phosphorescent Bodies. — M. Cle- 

 mandot. — The author maintains that phosphorescence is a 

 purely physical phenomenon, due to a vibratory action ex- 

 ercised chiefly by the blue ray of light. He connects these 

 phenomena of vibration in phosphorescent bodies with 

 those which light occasions in organized bodies. 



NOTE. 



I wish some one would begin with the start given by 

 the paper on polarization of sound, in "Science" for May 

 14, and thoroughly go through the subject of Etherial 

 Physics. 



The mechanics and elementary laws of action of the 

 Ether substance are needed. 



The seemingly rotary or spiral course pursued by the 

 particles conveying light and electricity, as shown in the 

 polarization of light and in that of magnetism, are 

 especial subjects of choatic conception. And there is 

 more beyond ! Samuel J. Wallace. 



NOTICE TO CORRESPONDENTS. 



The writer of a paper " On Ether " received by us, will much 

 oblige by forwarding his name and address. 



