KXCnVLEDGF c^ SCIENTIFIC NEWS. 



ifii 



connection with some wireless telegraphy researches, the son 

 of the author happened to note that in the tcleplionc of the 

 Tommasi coherer, located at the receiving station, there was 

 a "sound difference," which varied in accordance with the air- 

 gap in the interrupter of the Khumkorff apparatus. This 

 suggested the idea that a similar apparatus would bo capalilc 

 of transmitting the human voice to a distance without the 

 agency of the wire. The e.xpernnents had to be put off for 

 some time because of the lack of a suitable outfit ; but the 

 author was eventually enabled, through the courtesy of Pro- 

 fessor Marcel, of the Barcelona Seminary, to carry out his 

 idea. The experimental ;irrangenient is a rather simple one. 

 At the transmitting station there is a Rhumkorff apparatus 

 3cm. in spark length, as well as the necessary oscillator, a small 

 antennae, and an earthed conductor. Between the transformer 

 (i.(., the Rhumkorff" coil) and a small battery of Grenet cells, 

 there is a special microphone acting both as manipulator and as 

 interrupter. The autom.itic interrupter of the induction coil is 

 stopped, while the condenser is used for enforcing the oscil- 

 lator spark. At the receiving station, there is a Tommasi 

 coherer, connected to the receiving antenna;, and the earthed 

 conductor. In a telephone receiver, the noise produced l)y 

 the Hertzian waves on traversing the coherer is noted. On 

 approaching the mouth of the microphone and singing or 

 speaking, even,- sound vibration will be attended by an inter- 

 ruption in the passage of the electric current through the 

 primary circuit of the transformer, the number of sparks in the 

 oscillator thus being varied. The underlying principle shows, 

 therefore, some analogy with the mechanism in an ordinary 

 telephone. Any results so far obtained in the reproduction of 

 singing are said to be quite satisfactory, whereas the rendering 

 of language leaves much to be desired. The feeble point seems 

 to be the difficulty of designing a microphone of sufficient 

 intensity. Mr. Garcia, it is true, has remedied the imperfec- 

 tions of his apparatus to a certain extent by using a condenser 

 and augmenting the potential difference. This, however, 

 could not be driven too far, lest electric arcs be formed. 

 » * * 



On the Chemical Effect of Cathode Rays. 



Dr. E. Bose, of Gottingen University, has for two years 

 past made a close investigation of the simplest possible case 

 of a chemical action of cathode rays, with a view to ascertaining 

 whether or not the chemical conversion due to the rays is a 

 purely electro-chemical phenomenon according to Faraday's 

 law (see Physiltalische Zeitschyift, No. 12, June 15, 1904). X 

 solution of caustic potash, saturated in the hot state, was ex- 

 posed for a long time to the effect of cathode rays in a con- 

 venient outfit allowing of a large electrolyte surface — in fact, 

 about 200 sq. cm., being radiated upon intensely, when a 

 reduction, attended by the formation of hydrogen, was noted. 

 The amount of electricity absorbed by the electrolyte was 

 measured with the aid of a hydrogen voltmeter under reduced 

 pressure, this electricity being drawn off through a platinum 

 electrode sealed into the bottom of the testing tube. As the 

 hydrogen present in the vacuum where the discharges took 

 place was partly dissociated into hydrogen and oxygen, a 

 mixture of hydrogen and oxygen, containing hydrogen in 

 excess, was withdrawn by means of the mercury air pump, 

 and, after the gases due to this dissociation were eliminated 

 by an explosion, the hydrogen in excess could be measured, 

 and its pure condition confirmed. Now, in the case of the 

 chemical effect of the cathode rays following Faraday's law — 

 i.e., being a purely electro-chemical phenomenon — the amount 

 of hydrogen derived from the vacuum should be strictly the 

 same as the one evolved in the voltmeter. A high degree of 

 accuracy, it is true, was not to be anticipated, on account of 

 the smallness of the effects and amounts of electricity in 

 question, but the invariable result of the experiments was in 

 opposition to the foregoing hypothesis, 1030 and even more 

 times the amount obtained m the voltmeter being derived 

 from the vacuum. There must, therefore,be, besides the electro- 

 chemical action, another chemical effect of cathode rays, due 

 obviously to the kinetic energy of the cathode ray particles, 

 this hypothesis being borne out by the theoretical considera- 

 tions of the author. It is shown that, in the most favourable 

 case, an amount of hydrogen even 1600 times the electro- 

 chemical amount would be obtained. But it should be 

 remembered that, in most cases, the greater part of the 

 kinetical energy of the rays is simply transformed into heat. 



New Self-Recording Barometer. 



The new self-recording b.uomrter which Mr. W. II. Dines 

 has designed, and which is made by Mr. J. Hicks, of ll.itton 

 Garden, grapples in an original and satisfactory way with the 

 two problems of the recording barometer — the ditHcully of 

 registering very small dilferencos, and of ensuring a high 

 degree of accuracy. The curve traced by the recording pen 

 is accurate to the one-two-hundredth part of an inch. The 

 ends aimed at are attained by reducing the friction between 

 all moving parts, and by the ingenious device of an automatic 

 correction for temperature. The pen moves with a float in 

 the lower cistern (the motion being multiplied by a lever) ; 

 and this float is in the form of a hollow cylinder floating mouth 

 downwards in the mercury. A rise of temperature lowers the 

 level of the mercury in the lower cistern ; but at the same 

 time it makes the float swim higher in the mercm-y, because 

 the air in the hollow cylinder expands with the same increase 

 of temperature. The volume of air in the hollow float is so 

 adjusted as to make the compensation perfect. Another use- 

 ful device is the addition of what we may call a stationary pen, 

 which is fi.xed to the frame, and which draws a line of refer- 

 ence on the reel of paper wound on the clock drum of the 

 barometer. Any error in spacing tlie chart of the drum, or 

 any carelessness in placing the chart on the drum, is thereby 

 rectified, since this line can be taken as the zero line. 



G. 



ZOOLOGICAL. 



The English StodLt. 



The English stoat, according to Captain G. E. H. Barrett- 

 Hamilton, differs from the stoat of Scandinavia — the true 

 Mustela ci'inineii of Linn;eus — by having the tail coloured 

 uniformly all round, instead of with the under surface much 

 lighter than the rest. Moreover, it does not usually turn 

 white in winter. Consequently, it is regarded as a distinct 

 race — Mustela (or Puturius) cnniiiea stabilis. 



* * * 



Habits of African Fishes. 



Some very interesting observations, based on specimens 

 kept in the Aquarium, on the habits of many species of fish 

 from the Nile are recorded in the Director's report of the 

 Zoological Gardens at Giza, near Cairo, for last year. Many 

 of these refer to the long-snouted fishes of the family Morniy- 

 ridiC, all of which are peculiar to the African riv'ers, and some 

 of which have a muzzle comparalile to the trunk of an 

 elephant. In a natural state all these fishes appear to be 

 thoroughly nocturnal, but in captivity they soon learn to move 

 about during the daytime, when they will search for the 

 chopped worms on which they are fed. Specimens of the 

 long-nosed species, known as Monnyrits kannume, generally 

 spend the day lying quietly at the bottom of the tank, but 

 after nightfall become very active, searching energetically 

 after food. When a light is thrown on them their eyes shine 

 in a very remarkable manner, sometimes appearing white and 

 sometimes gleaming red. They have also a curious habit of 



swimming tail-first. 



* «• » 



Classification of Fishes. 



Considerable modifications of the generally-accepted 

 classification of fishes are suggested by Mr. C. T. Kegan in the 

 May number of the "Annals and Magazine of Natural History.' 

 The sturgeons and their extinct relatives are, for instance, 

 regarded as the most primitive representatives of the bony 

 fishes, and froni this group is derived the bisher of the Nile 

 and the other members of the now nearly extinct section of 

 fringe-finned ganoids; while from the latter are descended the 

 lung-fishes (such as the (jueensland baranumdaand the South 

 American and African lung-fishes), which have generally been 

 regarded as constituting a distinct order by themselves. 



* * * 



Alligators a.nd Crocodiles- 



A remarkable dis[)lay of ignorance and inaccuracy has been 

 recently displayed by a correspondence in the St. James's 

 Gazette with regard to the alleged occurrence of alligators in 



