July i6, 1903] 



NATURE 



261 



their attainments in classical fields. It is scarcely too much 

 to say that few of these men have welcomed the introduc- 

 tion of science into the school curriculum. But, for the 

 sake of recognition by county councils, and the consequent 

 grants, science has been given a place in grammar schools 

 as a paying guest. In many cases the headmasters know 

 nothing of science, and care less ; and the teachers in charge 

 of the science work receive little encouragement to do any- 

 thing but push on promising pupils to scholarship examin- 

 ations. It is, of course, impossible to discover the educa- 

 tional value of scientific studies under these conditions, 

 when no provision has been made for the supply of qualified 

 teachers, and while the idea still prevails among many 

 masters that text-books and lectures are the most important 

 means of imparting scientific knowledge. It would be 

 strange if the results of such teaching were satisfactory. 

 If Mr. Balfour and Sir William Anson will examine the 

 matter a little more closely, they will see that no fair 

 comparison can yet be made between the merits of classical 

 and scientific studies. Everything depends upon the method 

 by which the subject is taught, and the spirit which inspires 

 the teacher. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, May 14. — " The ' Elasmometer,' a New 

 Form of Interference Apparatus for the Determination of 

 the Elasticity of Solid Substances." By A. E. H. Tutton, 

 D.Sc, F.R.S. 



The apparatus is designed to measure the amount of 

 bending suffered by a thin plate of the substance investi- 

 gated, when supported near its ends against a pair of 

 platinum-iridium knife-edges, under a known weight 

 applied at its centre. It consists of an elaborate apparatus 

 for the support and adjustment of the plate and knife- 

 edges ; a measuring microscope, reading in two rectangular 

 directions by a new method to the thousandth of a millimetre, 

 for measuring the dimensions of the plate in situ ; a specially 

 constructed form of balance, one end of the beam of which 

 carries an agate point, through which a pressure is applied 

 under the centre of the plate equal to the weight in a pan 

 suspended from the other end ; a delicate control apparatus, 

 which only permits the weight to operate extremely slowly ; 

 an interference apparatus, of which the two reflecting sur- 

 faces concerned in the interference are (i) the lower surface 

 of a colourless glass disc supported on a tripod in rigid 

 connection with the knife-edges, and (2) the upper surface 

 of a smaller black glass disc forming the top of a counter- 

 poised rocker, arranged to move with the centre of the 

 plate and thus to transmit its motion. The amount of 

 diminution in the thickness of the air film between the two 

 glass surfaces, consequent on the bending of the plate, is 

 given by the number of interference bands which pass the 

 centre of reference, as seen in the micrometer eye-piece of 

 the observing apparatus, multiplied by half the wave-length 

 of the G or F hydrogen light which is employed. The 

 optical apparatus of the dilatometer previously exhibited is 

 utilised for the transmission of the hydrogen light to the 

 interference apparatus, and as observing apparatus. 



June 18. — " On the Discharge of Electricity from Hot 

 Platinum." By Harold A. Wilson, D.Sc, B.A., Fellow 

 of Trinity College, Cambridge. Communicated by C. T. R. 

 Wilson, F.R.S. 



This paper contains an account of a series of experiments 

 on the discharge of electricity from hot platinum wires. 

 The main object of the investigation was to determine the 

 influence exerted by the nature of the gas in which the 

 wire is immersed. 



It was found that the presence of traces of hydrogen in 

 the wire enormously increases the leak of negative elec- 

 tricity from it. By taking precautions to remove hydrogen 

 the negative leak was diminished to one part in 250,000 

 of its usual value. The presence of traces of phosphorus 

 pentoxide was found enormously to Increase the negative 

 ' ak, and it is known that alkali salts have a similar effect. 



he results obtained lead to the conclusion that the negative 



ak is due to the presence of traces of hydrogen, or. possibly 

 other substances, in the wire. 



With a particular wire in air, the small negative leak 

 remaining when impurities have been got rid of, as far 

 as possible, only falls off very slowly with time, and its 

 variation with the pressure of the air, the potential differ- 

 ence, and the temperature can be measured. 



It is shown that the variation of the negative leak with 

 the air pressure and potential difference is due to the ionisa- 

 tion of the air by collisions of the negative ions leaving the 

 wire with the air molecules. If the P.D. used is too small 

 to produce ionisation by collisions, the leak is independent 

 of the air pressure. 



The variation of the negative leak with the temperature 

 is investigated, and a formula which represents it is deduced 

 from thermodynamical considerations. 



The negative leak in hydrogen at various pressures is 

 measured and found to increase proportionally to the 

 pressure at low pressures. It is shown that the negative 

 leak depends on the amount of hydrogen occluded by the 

 wire. The following table gives the negative leaks at 

 1400° C. at several pressures in hydrogen 



Pressure. 



1330 m: 



0*II2 , 



00013 > 

 O'O ,, 



Current per sq. centim. 



I'O X io~^ ampere. 

 i'2xio-' „ 

 2 'OX io~^ ,, 

 1-2 xio"^" ,, 



The energy required for the production of a gram 

 molecular weight of negative ions is found to have the 

 following values : — 



(i) Thoroughly clean wire in air or 



vacuum ... 155,000 calories. 



(2) Cleaned wire in air or vacuum . 131,100 ,, 



(3) Wire in Hj at 00013 "im- ••• 120,000 ,, 



(4) .. ,, 0-II2 „ ... 85,900 ,, 



(5) M » i33"o „ ... 36,000 „ 



The paper also contains measurements of the positive 

 leak. It is shown that there is no positive leak appreciable 

 on a galvanometer from a clean wire in a vacuum. In air 

 or hydrogen there is a positive leak, which increases with 

 the gas pressure, and which is probably due to ionisation 

 of the gas molecules in contact with the hot platinum. 



It is probable that a pure platinum wire heated in a 

 perfect vacuum would not discharge any electricity at all, 

 either positive or negative, to an extent appreciable on a 

 galvanometer. 



" Upon the Bactericidal Action of some Ultra-violet 

 Radiations as Produced by the Continuous-current Arc." 

 By J. E. Barnard and H. de R. Morgan. Communicated 

 by Sir Henry Roscoe, F.R.S. 



The experiments described were carried out with the 

 object of determining the effect on the vitality of bacteria, 

 as the result of exposure to the arc spectra of carbon and 

 of various metals. 



The organisms experimented with have been the Bacillus 

 coli communis, B. prodigiosus, B. subtilis. Micrococcus 

 tetragenus, Staphylococcus aureus and Bacillus tuberculosis. 



The conclusion arrived at is that the bactericidal action 

 of light is almost entirely due to the action of those radia- 

 tions in the ultra-violet region of the spectrum which are 

 included between the wave-lengths 3287 and 2265. It is, 

 therefore, necessary that any source of light used as a 

 bactericidal agent should be rich in these rays. 



Royal Meteorological Society, June 17.— Captain D. 

 Wilson-Barker, president, in the chair. — Dr. W. N, Shaw, 

 F.R.S., read a paper on the meteorological aspects of the 

 storm of February 26-27. Between sunset of February 26 

 and noon of February 27, the British Isles were visited by 

 a storm of unusual severity. Its most impressive charac- 

 teristic was the amount of damage done to trees and build- 

 ings by gales from the south or south-west, particularly in 

 the neighbourhood of Dublin, where very large numbers of 

 trees were uprooted, and in Lancashire. Gales or strong 

 winds were also experienced in many parts of the British 

 Isles. Dr. Shaw exhibited lantern slides showing the path 

 of the barometric minimum and the area over which the 

 destruction extended. He also put forward some general 

 considerations about barometric depressions, and storms, 

 dealing more especially with the distribution of winds and 



NO. 1759, VOL. 68] 



