from observation if the aurora was always accompanied by discharges through the earth's surface. Except in the polar regions, these aurora do not seem to affect the normal fall of potential. There is a third view we may take as to the circulation of electric currents indicated by the aurora: the return current may take place in space outside the earth's atmosphere. A good deal might be said in favour of this view, and the rotation of the earth's magnetic field in space might be a sufficient cause for the production of these currents; but this is not the place to enter further into this question. Calculations made from observation on the height of the aurora have generally resulted in an altitude of from 100 to 200 miles, except in the polar regions, where the aurora seems occasionally to descend to a much lower level. It has also been noticed that aurora are associated with certain bands of cirrus clouds, and this seems to indicate that although the luminous phenomenon is sufficiently intense to be observed at only great heights, yet the electric phenomena may descend to the level of the cirrus. * As regards the connection between the aurora and the sunspot period, further observations in the polar regions are needed. On the one hand, we have Paulsen's statement, derived from observations in Greenland, to the effect that the greatest number of aurora are seen when sunspots are at their minimum, that is, at a time when in our own latitudes the number is smallest; and, on the other hand, we have Nordenskiöld's observations, which seem to point in the opposite direction. In a publication which contains much important matter on the geographical distribution and form of the aurora borealis, Nordenskiöld contrasts the appearances he has observed in the Vega during the winter of 1878-79, passed in the Behring Straits, with that previously observed in 1872-73 to the north of Spitzbergen. According to this author, the aurore, during the minimum sunspot period in 1878-79, were "hardly worthy of his notice by the side of those observed in 1872-73." But although only faintly luminous, the aurora of 1879 were persistent and regular in shape. They did not affect the magnetic field, and seem to show a regular and continuous, though weak, electric discharge. The arc and streamers in 1872 were much more brilliant and much more irregular. Some objection may be raised against these observations, in so far as they refer to different places, and local circumstances may have affected the phenomenon; but in the face of the very careful description he gives us, we cannot as yet accept Paulsen's results without further confirmation. The problem of atmospheric electricity, like that of terrestrial magnetism, presents special features in the arctic regions, and until we possess a greater number of observations in those little accessible * Paulsen, Danske Videnskab. Selskabs Forhand.,' 1889. (I have not seen the original memoir, but only an abstract in the Jahrbuch der Astronomie und Geophysik,' 1890.) 476 Professor Schuster on Atmospheric Electricity. [Feb. 22, parts of the earth's surface, many important problems cannot be satisfactorily solved. Arctic and antarctic expeditions are of interest to scientific men, not because they care much whether we get a few miles nearer the pole, but because a well-conducted party collects invaluable information on its journey. Although much remains to be done in the regions surrounding the north magnetic pole, our knowledge in the southern hemisphere is almost disgracefully inadequate, and it is to be hoped that before long a well-equipped expedition may fill up to a certain extent the large gaps in our electrical and magnetical knowledge which at present stop so many of our researches. But although investigations to be conducted in the Arctic regions are of primary importance, we may do much nearer home in extending and completing existing information. Instrumental appliances and methods of observation, originally put into a satisfactory state by Lord Kelvin, have been improved, especially by Mascart, Exner, Elster and Geitel. One of our most crying wants at present is a series of continuous observations by means of self-registering instruments in places where the neighbourhood of a town, or other local circumstances, do not interfere with the normal changes. Greenwich Observatory, to whom we look for help in such matters, is placed in the difficulty that the daily variations there observed are markedly different from those in the majority of places, and it is probable that the nearness of London is fatal to any generally useful series of observations of atmospheric electricity being conducted in our national Observatory. The [A. S.] WEEKLY EVENING MEETING, Friday, March 1, 1895. BASIL WOODD SMITH, ESQ., F.R.A.S. F.S.A. Vice-President, in the Chair. THE REV. CANON AINGER, M.A. LL.D. The Children's Books of a Hundred Years Ago. (No Abstract.) GENERAL MONTHLY MEETING, Monday, March 4, 1895. SIR JAMES CRICHTON-BROWNE, M.D. LL.D. F.R.S. Treasurer and Vice-President, in the Chair. George S. Albright, Esq. Edward George Betts, Esq. M.R.C.S. Reginald Arthur Bray, Esq. Matthew Bulloch, Esq. George Bywaters, Esq. G. Felix N. Clay, Esq. B.A. Charles Scott Dickson, Esq. M.A. James Garvie, Esq. Mrs. Alexander Goschen. Frederick Leverton Harris, Esq. M.A. E. G. Harrison, Esq. Stapleton C. Hogg, Esq. Ernest Law, Esq. His Grace The Duke of Newcastle. George Henry Ogston, Esq. Bertram Percy Portal, Esq. Spencer John Portal, Esq. Marmaduke Prickett, M.D. M.A. Lieut.-Colonel William W. Rawes, R.A. William Thomas Shaw, Esq. John Henry Skelton, Esq. James J. Walker, Esq. William Hall Walker, Esq. Arthur Fraser Walter, Esq. were elected Members of the Royal Institution. The Special Thanks of the Members were returned for the following Donations to the Fund for the Promotion of Experimental Research at Low Temperatures:— The Special Thanks of the Members were returned to Mr. Hugh Spottiswoode, for a portrait of his father, the late Mr. William Spottiswoode, M.R.I. The following Arrangements for the Lectures after Easter were announced : PROFESSOR GEORGE FORBES, M.A. F.R.S. M. INST. C.E.-Three Lectures on ALTERNATING AND INTERRUPTED ELECTRIC CURRENTS; on Tuesdays, April 23, 30, May 7. PROFESSOR E. RAY LANKESTER, M.A. LL.D. F.R.S.-Four Lectures on THIRTY YEARS' PROGRESS IN BIOLOGICAL SCIENCE; on Tuesdays, May 14, 21, 28, June 4. PROFESSOR DEWAR, M.A. LL.D. F.R.S. M.R.I. Fullerian Professor of Chemistry, R.I.-Four Lectures on THE LIQUEFACTION OF GASES; on Thursdays, April 25, May 2, 9, 16. WILLIAM HUGGINS, ESQ., D.C.L. LL.D. F.R.S. M.R.I.-Three Lectures on THE INSTRUMENTS AND METHODS OF SPECTROSCOPIC ASTRONOMY (The Tyndall Lectures); on Thursdays, May 23, 30, June 6. ARNOLD DOLMETSCH, Esq.--Three Lectures on MUSIC AND MUSICAL INSTRU MENTS OF THE 16TH, 17TH AND 18TH CENTURIES; 1. English. 2. French. 3. Italian. (With Illustrations upon Original Instruments.) On Saturdays, April 27, May 4, 11. SEYMOUR LUCAS, Esq. A.R.A.-Two Lectures on PICTURE MAKING; on Saturdays, May 18, 25. PROFESSOR EDWARD DOWDEN, D.C.L. LL.D. Professor of English Literature, Trinity College, Dublin.-Two Lectures on ELIZABETHAN LITERATUKE. 1. The Pastoral. 2. The Masque; on Saturdays, June 1, 8. The PRESENTS received since the last Meeting were laid on the table, and the thanks of the Members returned for same, viz. :— FROM Abney, Captain W. de W. C.B. D.C.L. F.R.S. (the Author)-Colour Vision, being the Tyndall Lectures delivered in 1894 before the Royal Institution. 8vo. 1895. Accademia dei Lincei, Reale, Roma-Classe di Scienze Fisiche, Matematiche e Naturali. Atti, Serie Quinta: Rendiconti. 1o Semestre, Vol. IV. Fasc. 1-3. 8vo. 1895. Classe di Scienze Morali, etc.: Rendiconti, Serie Quinta, Vol. III. Fasc. 10-12. 8vo. 1894. American Academy-Proceedings, New Series, Vol. XXI. 8vo. 1894. American Association-Proceedings, August Meeting, 1893, at Madison, Wisconsin. 8vo. 1894. Asiatic Society of Bengal-Proceedings, 1894, No. 9. 8vo. 1894. Astronomical Society, Royal-Monthly Notices, Vol. LV. No. 3. 8vo. 1894. Basel Naturforschenden Gesellschaft-Verhandlungen, Band X. Heft 2. 8vo. 1894. Bombay, the Under Secretary of Government, General Department-Progress Report 1894. Geology of the Boston Basis. By W. O. Crosby. Vol. I. Part 2. 8vo. 1891. Memoirs, Vol. III. No. 14. 4to. 1894. British Architects, Royal Institute of Journal, 3rd Series, Vol. II. No. 3. 4to. British Association-Report of Meeting at Oxford, 1894. 8vo. 1894. British Astronomical Association-Journal, Vol. IV. No. 11; Vol. V. Nos. 3, 4. 8vo. 1895. Camera Club-Journal for February, 1895. 8vo. Chemical Industry, Society of-Journal, Vol. XIV. No. 1. 8vo. 1895. Chemical Society-Journal for February, 1895. 8vo. Proceedings, Nos. 147, 148. 8vo. 1894. Cracovie, l'Académie des Sciences-Bulletin, 1895, No. 1. 8vo. Donisthorpe, Wordsworth, Esq. (the Author)—A System of Measures. 8vo. 1895. Editors-American Journal of Science for February, 1895. 8vo. Analyst for February, 1895. 8vo. Athenæum for February, 1895. 4to. Brewers' Journal for February, 1895. 8vo. Chemical News for February, 1895. 4to. Chemist and Druggist for February, 1895. 8vo. Electrical Engineering for February, 1895. 8vo. Engineering Review for February, 1895. 8vo. Nuovo Cimento for February, 1895. 8vo. Photographic News for February, 1895. 8vo. Photographic Work for February, 1895. 8vo. Rasa-Ranga-Rahasya, Vol. I. No. 6. 8vo. 1894. Scots Magazine for February, 1895. 8vo. Technical World for February, 1895. 8vo. Transport for February, 1895. fol. Tropical Agriculturist for February, 1895. Work for February, 1895. 8vo. Zoophilist for February, 1895. 4to. Florence, Biblioteca Nazionale Centrale-Bolletino, Nos. 219, 220. 8vo. 1894. Franklin Institute-Journal, No. 830. 8vo. 1894. Geographical Society, Royal-Geographical Journal for February, 1895. 8vo. Geological Society-Quarterly Journal, No. 201. 8vo. 1895. Gladstone, J. H. Esq. F.R.S. M.R.I. &c.-Records of the Tercentenary Festival of the University of Dublin in 1892. 4to. 1894. Tijdschrift van het Nederlandsch Aardrijkskundig Genootschap, Tweede Serie, Deel IX. X. 8vo. 1892-93. Huggins, Mrs. M.R.I. (the Author)-The Astrolabe. 8vo. 1894. Johns Hopkins University-American Chemical Journal, Vol. XVII. No. 2. 8vo. 1895. Linnean Society-Journal, No. 210. 8vo. 1894. London County Council (Technical Education Board)-London Technical Education Gazette, No. 5. 8vo. 1895. Meteorological Society, Royal-Quarterly Journal, No. 93. 8vo. 1895. Meteorological Record, No. 54. 8vo. 1895. Microscopical Society, Royal-Journal, 1895, Part 1. 8vo. |