454 



NA JURE 



[March 12, 1903 



of the Universities, a representative selected by the In- 

 corporated Association of Headmasters, another selected 

 by the Headmasters' Conference, another by the Royal 

 Society, and two members nominated by the Secretary of 

 State.' The settlement of the syllabus of examination will 

 be left in their hands. There is to be one and the same 

 examination for Woolwich and Sandhurst for the Army and 

 for the Militia. For University candidates, whom Mr. Brod- 

 rick is anxious to encourage, a scheme has been prepared 

 which will enable them to enter the Army on equal terms 

 with other candidates. A student will have to pass Moder- 

 ations at Oxford or some equivalent examination at another 

 University before he is twenty, and he will also have to do 

 six weeks' training with a Regular unit at Aldershot or else- 

 where. He will then be given a provisional commission. 

 Before he is twenty-two he will have to take honours at 

 the University and to go through another six weeks' train- 

 ing. He will then receive a commission dating back two 

 years. The Universities are to be asked to include in their 

 honours examination two or three military subjects — e.g. 

 military topography and military history. 



SOCIETIES AND ACADEMIES. 



London. 



Royal Society, January 22. — "Characteristics of Electric 

 Earth-current Disturbances and their Origin." By J. E. 

 Taylor. Communicated by Sir Oliver Lodge, F.R.S. 



The paper deals with disturbing effects, produced by rapidly 

 varying earth-currents, on a telephone receiver, connected 

 in a short line of telegraph having both ends earthed in the 

 sea. The sounds produced have certain well-marked 

 characteristics. In these latitudes they are always stronger 

 and of more frequent occurrence in summer than in winter. 

 They are daily in evidence for a few hours at, or about, the 

 time of sunset, i.e. whilst daylight is fading. In general 

 they do not evidence themselves to any great extent during 

 broad daylight, but are readily precipitated by a state of 

 electrical tension in the atmosphere which may culminate 

 in a thunderstorm, and rarely fail to herald the approach 

 of a storm or gale. 



Particularly noticeable among the various types of dis- 

 turbance enumerated, there are some which resemble the 

 distant scream of a rocket rising in the air. These com- 

 mence with a shrill whistle, and die away in a note of 

 diminishing pitch. They vary in intensity, but always have 

 a similar duration of from two to four seconds, are freely 

 heard at night, and only occasionally during the day. The 

 sound is characteristic of an initial high velocity rapidly 

 damped and dissipated. This type of disturbance is assumed 

 to be produced by the passage of meteoric bodies in suffi- 

 cient proximity to the circuit, which set up rapidly inter- 

 mittent electrical discharges in the upper regions of the 

 atmosphere, inducing electric currents in the sea which 

 affect the circuit. That they are only occasionally heard 

 during broad daylight is explained by the ionisation of the 

 upper atmosphere by solar radiations, possibly electronic, 

 which interposes a conducting screen. A high state of 

 electrical tension in the atmosphere nullifies or modifies the 

 conductivity produced. At nightfall solar radiations cease 

 to act, and conductivity disappears gradually. The night- 

 fall disturbances are accounted for by aerial electric currents 

 associated with the disappearance of ionic conductivity, the 

 effects of these aerial currents becoming perceptible so soon 

 as the conductivity becomes sufficiently small to act no 

 longer as a screen. It is suggested that similar causes 

 influence the diurnal variations of the earth's magnetic field, 

 and that the changes of ionisation of the atmosphere offer a 

 reasonable explanation of the greater night-time efficiency 

 in signalling recently observed by Mr. Marconi in experi- 

 ments with Hertzian wireless telegraphy. 



" Some Dielectric Properties of Solid Glycerine." By 

 Ernest Wilson, Professor of Electrical Engineering, King's 

 College, London. Communicated bv Sir William Preece, 

 K.C.B.. F.R.S. 



February 12. — "The Brain of the Archseoceti." By Dr. 

 G. Elliot Smith. Communicated bv Prof. G. B. Howes, 



F.R.S. 



no. 1 74 1, vol. 67] 



"Primitive Knot and Early Gastrulation Cavity _ Co- 

 existing with Independent Primitive Streak in Ornitho- 

 rhynchus." By Prof. J. T. Wilson and Dr. J. P. Hill. 

 Communicated by Prof. G. B. Howes, F.R.S. 



Linnean Society, February 19. — Prof S. H. Vines, F.R.S., 

 president, in the chair. — Mr. John Clayton, of Bradford, 

 presented a set of thirty-two photographs to illustrate the 

 celebrated Cowthorpe Oak, near Wetherby, Yorkshire. The . 

 author concludes that the age of the tree has been greatly 

 over-estimated, his own belief being that 500 years is the 

 extreme limit of its age, from sapling to its present decrepi- 

 tude and decay. — Dr. George Henderson offered some re- 

 marks on the possible uses of essential oils in the economy of 

 plant-life. Adverting to the well-known fact that moisture 

 in the air prevents radiation and consequent loss of heat, he 

 suggested that emanations of essential oil from plants might 

 possibly prevent damage by night frost during the period 

 of flowering, basing his suggestion on Prof. Tyndall's re- 

 searches thirty-two years since, on the presence of infini- 

 tesimal quantities of essential oil in the air. Tyndall found 

 such presence increased the absorptive power of the air as 

 regards heat-rays : taking dry air as 1, air saturated with 

 moisture as 72, then traces of essential oil rank as follows : — 

 Rosemary 74, cassia 109, spikenard 355 and aniseed 372. 

 Dr. Henderson brought these remarks before the meeting 

 as an interesting question for botanic investigation, since 

 essential oils are usually regarded as mere waste products. 

 — The Rev. T. R. R. St'ebbing, vice-president, having taken 

 the chair, the first paper, on the electric pulsation accom- 

 panying automatic movements in Desmodium gyratis, by- 

 Prof. J. C. Bose, was summarised by the president for the 

 author. In this paper Prof. Bose gives the results of his 

 investigation of the question as to whether or not spon- 

 taneous movements are accompanied by an electric dis- 

 turbance comparable to that resulting from external stimu- 

 lation. Spontaneous movements are not uncommon in the 

 higher plants, but for various reasons there are but few 

 instances suitable for an investigation of this kind. The 

 most striking case is that of Desmodium gyrans, the tele- 

 graph-plant. The leaf of this plant is trifoliolate, consist- 

 ing of two small lateral leaflets and a larger terminal leaflet. 

 The lateral leaflets move up and down, like the arms of a 

 semaphore — whence the popular name of the plant — the 

 period of a complete up and down movement, in the plants 

 observed, being about 35 minutes. Having placed one 

 electrode on the petiolule of a leaflet and the other on the 

 petiole of the leaf, both in connection with a galvanometer, 

 Prof. Bose found that the spontaneous movement is associ- 

 ated with an electrical disturbance of a peculiar kind. There 

 is first a large principal wave of disturbance, followed by 

 a smaller subsidiary wave, the period of the former being 

 about 1 minute, that of the latter about 23 minutes. This 

 disturbance is the expression of a " current of action " 

 travelling in the plant from the excitable petiolule to the 

 resting petiole. — A paper by Miss A. L. Embleton, com- 

 municated by Prof. G. B. Howes, was read by Mr. A. D. 

 Michael for the author, on Ceraiaphis Lataniae, a peculiar 

 Aphid. This insect was observed in 1901 on various 

 orchids in the Cambridge University Botanic Garden. The 

 author gives the detailed synonymy of the creature, which 

 is well known to cultivators on the Continent, and proceeds 

 to set out its life-history ; in this country it exists in only 

 one form, reproduced parthenogenetically, corresponding to 

 an aleurodiform stage of a migratory Aphis. The author 

 concludes by suggesting that it is one of the migratory 

 Aphides which has been deprived of its usual series of meta- 

 morphoses owing to an artificial mode of life. — On special- 

 isation of parasitism in the Erysiphaceae, by Mr. E. S. 

 Salmon. The author began by explaining the term 

 " biologic form " or " species " by instancing two fungi 

 which were not distinguishable morphologically, acting in 

 diverse fashion on the same host-plants. This phenomenon 

 has been known in the Uredinese for some time, but its dis- 

 covery in the Erysiphaceae was more recent. 



Royal Microscopical Society, February IS. — Dr. Henry 

 Woodward, F.R.S., president, in the chair. — Dr. Arthur 

 Rowe gave a demonstration on the photomicrography of 

 opaque objects as applied to the delineation of the minute 

 structure of chalk fossils. Dr. Rowe said the photomicro- 



