May 1 6, 1907] 



NATURE 



59 



Relay working of long submarine telegraph cables. The 

 apparatus consists of (i) an automatic transmitter, the 

 movements of which are governed by means of a perforated 

 tape, and originate the signals sent into an imitalion 

 cable; (2) a relay, receiving the signals at the other end 

 of the line, and actuating an automatic perforator by 

 which a duplicate of the originating type is reproduced at 

 the relay station for re-transmission on another cable. — 

 .Sir James Devjar, F.R.S. : The Crookes radiometer — 

 motion arrested in very high vacua, &c. (i) Experiments 

 showing the cessation of radiometer action in very high 

 vacua, made by charcoal cooled in liquid hydrogen or 

 liquid air, even when the instrument is subjected to the 

 concentrated radiation of an electric lamp. (2) Radiometer 

 filled with helium at atmospheric pressure, which is in- 

 active to a charcoal liquid-air vacuum, but becomes active 

 in a charcoal liquid-hydrogen vacuum. — Mr. II'. Duddell, 

 F.R.S. : Persistent electric oscillations. The oscillations 

 are produced by the method of the " musical arc." In 

 this method a direct-current arc is shunted with a circuit 

 consisting of a condenser and a self-induction in series. 

 The frequency of the oscillations can be varied by altering 

 either the capacity or the self-induction in the shunt circuit. 

 The oscillograph records exhibited show the variations in 

 the potential difference and current when the oscillations 

 are produced. To obtain powerful oscillations at very 

 high frequencies, the arc may be placed in hydrogen gas 

 as employed by Paulsen. In the apparatus shown the arc 

 burns in coal gas, and no magnetic pehi is used to blow 

 out the arc. Experiments in magnetic induction, tuning, 

 and discharge I'li vacuo are easily demonstrated with 

 persistent high-frequency oscillations. The persistent 

 oscillations are of special use for energising the trans- 

 mitter in wireless telegraphy, as they permit better 

 syntony or tuning to be obtained. — Mr. W. .i. Douglas 

 Riidge : The action of radium and other salts on gelatin 

 culture medium. Radium, barium, strontium, and lead 

 salts, when placed in contact with gelatin culture medium, 

 give rise to a kind of cellular growth, which is due to the 

 formation of an insoluble precipitate with the sulphuric acid 

 usually present. Radium salt added to the medium from 

 which the sulphuric acid has been removed causes no 

 growth, but the addition of a soluble sulphate produces a 

 growth at once. Analyses of the growths obtained with 

 radium salts show that they are composed of barium 

 sulphate. 



.Messrs. R. and J. Beck. Ltd. : (i) New diffraction wave- 

 length spectroscope. This instrument comprises a Thorpe 

 replica diffraction grating with a collimator and slit. The 

 observing telescope swings on an axis which passes through 

 the grating, parallel with the lines. The motion is by 

 means of a micrometer screw which reads the sine of angle 

 of rotation direct, thus giving on its divided milled head 

 the wave-length in A.U. (2) The " isostigmar " photo- 

 graphic lens on optical testing bench. — Mr. .4. Kershaw : 

 A new visual method of measuring the speeds of photo- 

 graphic shutters. — Mr. I'lrich Behn : (i) The flame tube. 

 .\ simple apparatus capable of Indicating very small 

 changes of air-pressure. It consists o- a short metal tube 

 with wide outlets, at which, after the tube is connected 

 with the gas main, the gas is lighted. It shows, if one 

 end is raised a few millimetres, the decrease of atmo- 

 spheric pressure with height by the changes in size of the 

 flames. The tube is capable of various applications. 

 (2) Demonstration of the theory of microscopic images, 

 fji .\n indirect method of measuring the temperature of 

 liquid-air baths. (4) .\ short glycerine barometer. This 

 consists of an air thermometer of the old Italian type, the 

 bulb of which is kept at zero bv means of ice in a Dewar 

 v.-^kpI.— Dr. /. T. Botlomlcy,' F.R.S.. and Mr. F. .-1. 

 King : Experiments with vacuum gold-leaf electroscopes 

 iin the mechanical temperature effects in rarefied gases. 

 The apparatus consists of a " radium clock " and various 

 types of vacuum electroscopes. The vacuum electroscopes 

 are set up to show the effects of radiations from sources 

 of heat and light upon gold leaves hanging within highly 

 f-Nhausted enclosures. The gold leaves of the vacuum 

 electroscope diverge when illumination of any kind falls 

 upon them, and stand permanently apart when placed in 

 bright daylight. By suitably manipulating such sources 

 as a spirit flame, candle, or Xernst lamp near the electro- 



NO. 1959, VOL. 76] 



scope, forces, which vary in clirrnion and magnitude from 

 point to point within the enclo-ure, are generated, and 

 cause the leaves to be twisted into curious shapes. The 

 gold leaves will remain in this contorted condition for a 

 considerable time after the exciting cause has been re- 

 moved. — Dr. J. R. .Milne : A special camera for the pur- 

 pose of automatically recording the readings of the scale 

 of any instrument. — Messrs. Pill;ington and Cibbs, Ltd. : 

 A heliochronometer which gives Greenwich mean time by 

 a simple direct solar observation. It comprises devices for 

 adjustment in latitude, longitude, level, and azimuth, and 

 is self-correcting for the equalion of time. 



The Cambridge Scientific Inslnnnent Co. : (i) Prof. Fury's 

 self-contained radiation pyrometer. The pvrometer utilises 

 the heating effect of the " total radiation " from a hot body, 

 focussed as an image of that body by means of a concave 

 mirror. It differs from the already known Firy radiation 

 pyrometer in being entirely self-contained, the image falling 

 upon a minute bi-metallic flal spiral (Breguet spiral). 

 This becomes partially uncoiled as its temperature rises, 

 and a light pointer attached moves over a dial divided to 

 give direct (centigrade) temperature readings. (2) Universal 

 portable electrometer, designed by Mr. C. T. R. Wilson, 

 F.R.S. A gold-leaf instrument with very small capacity 

 and fused quartz insulation, suitable for work on atmo- 

 spheric electricity, radio-activity, &c., and self-contained, 

 with means for standardising tlie readings, which are very 

 steady even in a fairly high wind. — Mr. Joseph Goohi : 

 Vibration experiments with steel plates and six bars tuned 

 accurately to 400, 500, 504, 600, 700, and Soo vibrations 

 per second. — Dr. Otto .Schlich, and Messrs. Swan, Hunter, 

 and Wighani Richardson, Ltd. : Working models illus- 

 trating the action of the .Schlick gyroscope in steadying 

 ships at sea (see Nature, April 11, p. 561). — Dr. Robert 

 Kno.K and Mr. G. Pearce : Skiagraphy of the human sub- 

 ject ; examples illustrating the advantages of reduction in 

 exposure. The instruments employed to produce skia- 

 graphs, with exposures varying from one to seven seconds, 

 consist of a powerful induction coil yielding a greatly 

 intensified secondary current, worked in conjunction with 

 an electrolytic interrupter directly from high-tension 

 electric light mains. The core of the coil consists of 

 transformer plates. The primary is of a much larger wire 

 than usual, and has more turns. The secondary is smaller 

 than usual. The X-ray lube is provided with a heavy 

 anode to withstand the current. In series with the X-ray 

 tube, a rectifier is placed to render the current uni- 

 directional. 



The Thermal Syndicate, Ltd., Wallscnd-on-Tyne : 

 Pure fused silica ware. The articles consist of pure silica', 

 and are manufactured by an electric furnace process at 

 a temperature of about 2000° C. The material is highly 

 refractory, and possesses a very low coefficient of expansion 

 (about I /17th of that of glass), and in consequence it is 

 able to resist sudden and extreme changes of temperature 

 without cracking. It is unaffected by practically all acids, 

 is an excellent electric insulator, and retains its insulating 

 properties even at high temperatures. The specimens show 

 that it is possible to produce a brilliant lustre on the surface 

 of the material.— Dr. F. D. Chaitaway, F.R.S. : Copper 

 mirrors deposited upon glass frcm aqueous solution. In 

 the mirrors exhibited, the copper had been deposited upon 

 the glass by reducing cupric oxide by an aqueous solution 

 of phenylhydrazine in presence of potassium hydroxide, 

 which accelerates the action to a remarkable extent. The 

 mirrors are equal in brilliancy and uniformity of surface 

 to silver mirrors, and on account of the colour of the 

 copper are much more beautiful. — Hon. C. .4. Parsons, 

 F.R.S. : Photographs of microscopic diamonds obtained 

 from pure iron heated in a carbon crucible in an electric 

 furnace and rapidlv cooled. Scale, 150 diameters.- -Pro/. 

 J. Perry, F.R.S. : British .Association .Mbum, meeting in 

 South .Africa, 1005. Two copies of an album prepared by 

 Mr. Eustace Calland from photographs selected from those 

 taken by members of the British Association. 



Marine Biological Association of the United Kingdom: 

 Marine alga? and their reproduction. A small represent- 

 ative collection of sea-weeds from the Plymouth district 

 exhibited to illustrate their different habits of growth and 

 reproduction.— Pro/. E. Ray Lankester, F.R.S.: (i) Meta- 

 morphosis of the eel. Series of specimens showing the 



