Nov. 24, 1887] 



NA TURE 



95 



of these phenomena during the several hours of the day for the 

 twenty years ending 1884: — 



Hours. 



Midt. to I a.m. 



1 to 2 a.m. 



2 to 3 a.m. 



3 to 4 a.m. 



4 to 5 a.m. 



5 to 6 a.m. 



6 to 7 a.m. 



7 to 8 a.m. 



8 to 9 a.m. 



9 to 10 a.m. 



10 to II a.m. 



11 to noon. 



■26 



Sumntier — 



June, July, 



August. 



Year. 



Thus the daily maximum for thunderstorms is from about noon 

 to 7 p.m., being t'le period of the day covered by the afternoon 

 minimum of atmospheric pressure in summer ; but the maximum 

 for sheet lightning is from 8 p.m. to midnight, being the 

 period embraced by the afternoon maximum of pressure. The 

 absolute daily maximum for sheet lightning, it will be observed, 

 does not occur till from 9 to 11 p.m., or till soue time after 

 dusk, and cannot therefore be accounted for by increased visi- 

 bility as darkness sets in. The opinion is widespread that sheet 

 lightning is merely the reflection of a distant flash of lightning. 

 The Oxford observations show, however, that only a small per- 

 centage of all the cases admit of being explained in this way. 

 In connexion with the well-defined maximum from 9 to il p.m. 

 it may be remarked that there is no region of the globe nearer 

 Oxford than America where thunderstorms with the accom- 

 panying true lightning have the daily maximum at the same 

 physical time, 9 to 11 p.m. G. M.T., when sheet lightning has 

 its daily maximum at Oxford. 



The curve for auroras has its diurnal maximum substantially 

 at the same time as sheet lightning, or during the time of the 

 evening maximum of pressure. The agreement of these two 

 maxima with this portion of the daily curve of pressure is all the 

 closer when it is considered that the evening maximum of 

 pressure is from one to two hours later in summer when the 

 sheet lightning was observed than in the autumn and spring 

 months when the great majority of auroras occur. These results 

 are of the greatest importance with respect to recent theories 

 regarding thunderstorms, and to suggested connexions between 

 the aurora in arctic and sub-arctic regions and the lightnings of 

 low latitudes. The time of occurrence of the maxima of aurora 

 and sheet lightning from 9 to 11 p.m. indicates, perhaps, a more 

 direct connexion between these phenomena and the evening 

 maximum of pressure than has been suspected. This maximum 

 is mainly due to an overflow of upper aerial currents back to 

 eastward from the longitudes to westward, where at the time 

 the afternoon pressure is at the mini num (" Encyc. Britt.," 

 Meteorology, p. 122) ; and hence at these hours there is more 

 aqueous vapour spread through the higher regions of the atmo- 

 sphere in its gaseous and fluid states, and also in the solid state 

 of minute spicules of ice, even though no cloud in the finest 

 pencilled forms of the cirrus be visible. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge. — Drs. Routh and Glaisher, Prof. J. J. Thom- 

 son, and Mr. A. R. Forsyth have been appointed Examiners in 

 Part II. of the Mathematical Tripos of 1888. 



The following appointments of Natural Science Examiners 

 have been made : — Physics : Profs. J. J. Thomson and W. G. 

 Adams. Chemistry : Prof. H. E, Armstrong and Mr, H. J. 

 H. Fenton. Mineralogy : Messrs. T. W. Danby and H. A. 

 Myers (British Museum). Botany : Prof. I. B. Balfour and 

 Dr. S. H. Vines. Physiology : Dr. W. H. Gaskell and Prof. 

 G. F. Yeo. Zoology : Messrs. H. Gadow and W, F. R. 



Weldon. Geology: Prof. C. Lapworth and Mr. A. Harker. 

 Human Anatomy : Prof. J. Cleland and Dr, A. Hill. Pharma- 

 ceutical Chemistry : Mr. Pattison Muir. 



At a meeting of the Senate in the Arts School recently, 

 general approval was expressed of the scheme f)r providing a 

 new room for botanical microscopy. The scheme for new 

 anatomical and physiological rooms was not so entirely approved, 

 some persons wishing to retain the ugly old Anatomical Museum 

 and buildings, and also considering that the requirements of the 

 Medical School had not been sufficiently considered. 



Mr. W. Bateson, M.A., Fellow of St. John's College, has 

 been elected to the Balfour Studentship. 



Group E (Natural Science), in the Higher Local Examination, 

 attracts a diminishing number of candidates, we are sorry to see. 

 Only 36 presented themselves this year as against 73 in 1879 ; 

 but 10 candidates gained a first class this year, as against 4 in 

 1879 : 35 failed then, only 5 this year. Elementary Biology is 

 reported on fairly this year ; but Elementary Chemistry does not 

 seem to have been studied practically, and problems were not 

 satisfactorily dealt with. Only four candidates passed in Physics. 

 The Physiology, Zoology, and Geology papers were well 

 answered ; but in Botany the general standard was decidedly 

 low. 



SOCIETIES AND ACADEMIES. 



London. 



Entomological Society, November 2. — Dr. D. Sharp, Presi- 

 dent, in the chair.— Mr. Stevens exhibited a specimen of 

 Acidalia i'umo'-ata, L., purcha-ed by him some years ago at the 

 sale of the collection of the late Mr. Desvignes. He remarked 

 that specimens of the insect lately captured near Lewes had been 

 described last month by Mr. J. H. A. Jenner as a species new to 

 Britain. — Mr. Adkin exhibited, and made remarks on, a series 

 of male and female specimens of Arctia meniica from co. Cork ; 

 also, for comparison, two specimens of ^. mendica from Antrim, 

 and a series of bred specimens from the London district.— Mr. 

 Enoch exhibited a specimen of Calocoris bipunctatus containing 

 an internal parasitic larva.— Dr. Sharp exhibited three species of 

 Coleoptera new to the British list, viz. Octhebius auriculatus, 

 Rey, found some years ago in the Isle of Sheppey, but described 

 only quite recently by M. Rey from specimens found at Calais 

 and Dieppe ; Limnius rivularis, Rosenh., found by Dr. J. A. 

 Power at Woking ; and Tropiphorus obtusus, taken by himself 

 on the banks of the Water of Cairn, Dumfriesshire.— Dr. Sharp 

 also exhibited a Goliathus recently described by Dr. O. Nickerl 

 as a new species under the name of Goliathus atlas, and re- 

 marked that the species existed in several collections, and had 

 been supposed to be possibly a hybrid between G. regius and G. 

 cacicus. — Mr. Eland Shaw exhibited two species of Orthoptera, 

 which had been unusually abundant this year, viz. Nemohius 

 sylvestris, and Teitix subulatus.—yir. E. B.Poulton exhibited 

 the cocoons of three species of Lepidoptera, in which the colour 

 of the silk had been controlled by the use of appropriate colours 

 in the larval environment at the time of spinning up. He said 

 this colour-susceptibility had been previously proved by him in 

 1886 in the case of Saturnia carplni, and the experiments on the 

 subject had been described in the Proc. Royal Society, 1887. It 

 appeared from these experiments that the cocoons were dark 

 brown when the larvae had been placed in a black bag ; white 

 when they had been freely exposed to light with white surfaces 

 in the immediate neighbourhood. Mr, Poulton stated that other 

 species subjected to experiment during the past season aflforvled 

 confirmatory results. Thus the larvre of Eriogaster lanestris had 

 been exposed to white surroundings by the Rev. W. J. H. 

 Newman, and cream-coloured cocoons were produced in all 

 cases ; whilst two or three hundred larvse from the same company 

 spun the ordinary dark brown cocoons among the leaves of the 

 food-plant. In the latter case the green surroundings appeared 

 to act as a stimulus to the production of a colour which corre- 

 sponded with that which the leaves would subsequently assume. 

 Mr. Stainton suggested that larvae should be placed m green 

 boxes, with the view of ascertaining whether the cocoons would 

 be green. It had been suggested that the cocoons formed 

 amongst leaves became brown because the lar^'se knew w.iat 

 colour the leaves would ultimately become. The discussion was 

 continued by Mr. Waterhouse, Dr. Sharp, Mr. McLachl.n, and 

 others.— Mr. S. Klein read " Notes on Ephcstia kuhmella, and 

 exhibited a number of living larvse of the species, which he said 



