October 30, 1919] 



NATURE 



187 



the offer when planning their post-graduate work. 

 For the present the studentships are limited to men, 

 though with the development of the scheme it is 

 hoped that it will cover fields open to research workers 

 of both sexes. The studentships appear to offer con- 

 siderable attractions to young economic botanists, but 

 the joint committee will no doubt consult the heads 

 of the botanical schools as to the probable cause of 

 the poor response to its first offer, with the object 

 of mitigating any drawbacks which may have become 

 apparent in the scheme. We venture to suggest also 

 the desirability of indicating a selection of typical 

 problems with which the cotton industry is confronted. 



SOCIETIES AND ACADEMIES. 



M.-VNCIIESTER. 



Literary and Philosophical Society, October 21. — Mr. 

 William Thomson, vice-president, in the chair. — Prof. 

 W. L. Bragg : Sound-ranging. A sound spreads from 

 the point where it originates as a spherical cone 

 moving with constant velocity. If it is intercepted by 

 three or more stations the positions of which are 

 accurately known, and if the time-intervals elapsing 

 between its arrival at the stations are measured, a 

 simple construction gives the position of the sources 

 of the sound. Soon after the commencement of hos- 

 tilities it became clear that the struggle Was going to 

 take the form of trench warfare. This gave rise to 

 the idea of locating the enemy guns by sound in the 

 wav described. The French made experiments with 

 sound-ranging in October, 1914, and showed that it 

 was feasible, and the British Army was encouraged by 

 their success to send an experimental sound-ranging 

 section to the Front. This section started op.erations 

 in October, 1915, taking up its position opposite 

 Wytschaete. The first results obtained were poor, 

 but they improved with experience and better ap- 

 paratus. The original section became a training 

 school for officers and men, and sufficient sections 

 were formed to cover the whole of our Front. Each 

 section had six microphones spaced along a base 

 opposite the German front line. The microphones 

 were connected to a chronographic instrument at a 

 central headquarters, and when the sound reached 

 each microphone it sent an electric signal recorded 

 by the . instrument. In front of the base there were 

 two observation posts so placed that the sound reached 

 them a few seconds before it reached the microphones, 

 which gave time for an observer at the post to press 

 a key which started the recording apparatus at head- 

 quarters. By studying the record the time-intervals 

 could be measured and the position of the gun plotted 

 on the map and telephoned to the artillery. There 

 were between thirty and forty sections along the 

 Front. Thev could locate batteries between 10,000 and 

 15,000 vards away with a mean error of about fifty 

 yards. Each section sent in about one thousand results 

 in the year. 



Paris. 



Academy of Sciences, September 29. — M. L^on 

 Guignard in the chair. — A. Rateau : Speech given at 

 the James Watt centenary dinner, September 17, 1919,31 

 Birmingham. — MM. Blondel and Touly : New arrange- 

 ments of universal potentiometer amplifiers.- -Albert, 

 Prince of Monaco : Stray mines in the North Atlantic. 

 In December, 1918, the author gave a chart showing 

 the probable course of floating mines in the North 

 Atlantic, with the view of minimising the danger to 

 navigation. Since then thirty-three mines have been 

 located, the positions of which are shown on an 

 accompanying map. The conclusions of the first note 

 are confirmed. — J. Wolff : Series of holomorphic func- 



NO. 2609, VOL. 104] 



tions. — M. Foch : The period of water-mains furnished 

 with an air-cushion.- — M. Grard : Thermal treatment 

 of aluminium alloys. The alloys studied contained 

 3'&~4 PSf cent, of copper, about 05 per cent, of 

 magnesium, and from 0-5-1 per cent, of manganese, 

 and were of the duralumin type. The treatment 

 giving the alloy the maximum malleability was 

 found to be heating to 450° C, with a cooling 

 velocity of 100° C. per hour. Heating to 475° ( ., 

 followed by immersion in water at 20° C, gave the 

 highest elastic limit and breaking strain.- —.A. Ricco : 

 Heliographic latitudes of the solar protuberances 

 (1880-1918). The observations are summarised both 

 in tabular and graphical form, the general conclusions 

 being more clearly shown by the latter.— C. Benedicks : 

 The thermo-electricity of liquid mercury demonstrated 

 by means of the galvanometer. In an earlier paper 

 the author has shown that thermo-electric currents of 

 the first species can be proved in a column of liquid 

 mercury asymmetrically heated. These results have 

 been called in question, and confirmation bv a different 

 method is now given. — M. Delpech : The flashes pro- 

 duced by the fire of artillery, and a general method 

 for the extinction of these flashes. For small-bore 

 cannon (47 mm.) a simple lubrication of the projectile 

 with vaseline suffices to prevent the flash ; for larger 

 bores the addition of vaseline to the powder serves 

 the same end. — P. Thiery : Some new observations 

 on the klippes of the .Alais Plain. — Mile. M. Gold- 

 smith : The behaviour of Convoltita roscoffensis in 

 presence of the rhythm of the tides. — F. Ladreyt : 

 Physiological dedifferentiation and cellular reinvigora- 

 tion in intestinal epithelium. 



Calcutta. 

 Asiatic Society of Bengal, September 3. — Hashmat Rai 

 and H. B. Dunniclifl : The purification of Indian 

 sesame ("til") oil. The following conclusions were 

 arrived at : — (i) Of all the filtering materials used, 

 bone charcoal and French chalk are the best de- 

 colorising agents; all of them are ineffective as deo- 

 dorisers. (2) Exposure to sunlight alone gives pro- 

 gressive improvement in colour, but the odour still 

 persists. (3) Treatment with air alone improves the 

 colour, but the odour is not removed. (4) Exposure 

 to both air and sunlight combined has a very marked 

 effect on the colour. The odour, though not absent, 

 is not unpleasant. (5) Sulphuric acid reduces the 

 colour very slightly, but the odour practjcally dis- 

 appears. (6) Caustic soda acts both as a very good 

 decolorising and a deodorising agent. (7) In all the 

 bleached samples the colour more or less comes back 

 on standing for a long period. (8) On heating all the 

 deodorised samples the odour becomes perceptible. 

 On cooling, however, it disappears. — Hashmat Rai : 

 Note on nitrogen. A new method of preparation. 

 Nitrogen gas may be readily prepared by passing an 

 electric current through an ammonium chloride solu- 

 tion with platinum foil electrodes, the anode and the 

 cathode chambers being separated by a porous dia- 

 phragm. Air is excluded from the electrolytic cell 

 and the connecting tubes. The anodic gas is prac- 

 tically pure nitrogen, containing less than 0-2 per 

 cent, of oxygen. It should, however, be collected 

 over caustic soda solution so as to absorb anv chlorine 

 gas that may possibly be mixed with it. This affords 

 a ready method for the preparation of a continuous 

 supply of pure nitrogen. — N. N. Chatterjee : The 

 rationalisation of algebraic equations. .An earlier 

 paper on the subject by the author was referred to 

 in a paper by Prof. Mahendra Nath De, "The 

 Rationalisation of .Algebraic Equations " (J.A.S.B., 

 July, 1908), in which objection, was taken that the 

 method does not always lead to an equation of the 



