originally moving in the direction of propagation with a velocity slightly less than that of radiation may be picked up by the waves and carried forward with the velocity of radiation.

The conclusion is that the propagation of disturbances of any form in a straight line involves a sorting of free ions and molecules according to their initial circumstances, and streaming of these both with and against the waves must take place.

These results are general, and are limited only by the limits of the electrodynamic equations. They suggest, however, a possible explanation of the action of all kinds of ionising agents.

In particular, it is suggested that if a radio-active substance is an origin from which electromagnetic disturbances are radiated, these disturbances probably ionise the gas in the immediate vicinity and produce streaming of ions and molecules with their associated properties both outwards from and inwards to the substance. This view does not necessarily involve the supposition that there is a continual diminution of the substance.

The results may also throw some light on the question of the energy sent out. For, suppose that there exist a positive and a negative ion which, in the absence of the pulses, would recombine at some point A, thereby radiating a certain amount of energy, then the directive action of the pulses may make them recombine at some other point B. Thus the radiated energy will proceed from the point B instead of from the point A. The transference of a single free ion can be accomplished without the expenditure of energy, and it is possible that the transference of the positive and negative ions may take place without any abstraction of energy from the pulses. Since, however, in general the transference may involve a relative displacement of the two ions, abstraction of energy from the pulses may be involved, so that the question is one about which the greatest caution must be exercised. It cannot be decided without further investigation.

These considerations are in general agreement with the views that have been expressed by Lord Kelvin and Prof. and Madame Curie.

The question whether the apparent velocity of drifting may be of the order indicated by experiment is considered; and it is shown that in order to give velocities comparable with that of radiation, the theory leads us to expect that the frequency of vibration of the waves radiated by the particles should be of the order for visible or ultra-violet light.

The differences between ionising agents would turn to a considerable extent on the character of the disturbances radiated.

Since the propagation of waves through a region of space containing matter involves streaming of the matter, the continued propagation cannot be quite independent of any statical, electric or magnetic field present.

February 2. Note on the Determination of the Volume Elasticity of Elastic Solids." By Dr. C. Chree, F.R.S. PARIS.

Academy of Sciences, February 13.-M. Troost in the chair. On the existence of an ellipsoid of absorption in all translucid crystals, even when without a plane of symmetry or a principal axis: J. Boussinesq.-Study of the silicide of carbon from the Cañon Diablo meteorite: Henri Moissan, In the residue left after dissolving a block of this meteorite weighing 53 kilograms in hydrochloric acid, a hexagonal crystal of silicon carbide was noticed. It was completely identified by its appearance, density (3-2), and indifference to most chemical reagents. Fused caustic potash gave potassium silicate, and fused lead chromate, carbon dioxide. The origin of this block of iron may be terrestrial or sidereal, but the existence of silicon carbide in the midst of the metal shows that the products prepared with the electric furnace are met with in nature.-On some constants of pure methane, and on the action of solid methane on liquid fluorine: H. Moissan and Chavanne (see p. 400).-The eruptive basic rocks of French Guinea: A. Lacroix. Besides biotite granite, numerous basic eruptive rocks have been found in French Guinea, especially gabbros, peridotites, and diabases, a detailed account of which is given. Attention is directed to the difference in the mode of weathering in tropical and in temperate climates, as exemplified in these samples.-On the use of photography as an aid to

a

topography: A. Laussedat. An account of an application of the photographic method to the survey of the region round Mount Argée, in Cappadocia, on a scale of 1/80,000. The use of photography has the advantage of reducing very considerably the time required as compared with the ordinary methods of surveying, and is especially advantageous in mountainous regions.-Observations of the Borrelly comet (1904 e) made with the Brunner equatorial at the Observatory of Lyons: J. Guillaume. The apparent position of the comet was measured on January 3, together with the positions of two comparison stars. The comet appeared as an object of the tenth magnitude, and possessed a small nucleus.-Observations of the sun made at the Observatory of Lyons with the 16-centimetre Brunner equatorial during the fourth quarter of 1904 J. Guillaume. The results are summarised in three tables giving the number of spots, their distribution in latitude, and the distribution of the faculæ in latitude.-Actinometric observations made at the summit of Mont Blanc: A. Hansky. The observations were made in the observatory at the summit of Mont Blanc with the instruments of M. Crova. The conditions in 1900 were more favourable than in 1897 and 1898, and the results for this year are given in detail, the most probable result for the constant being between 3.0 and 3.5.-On linear partial differential equations: M. Hadamard. On the deviation of falling bodies: Maurice Fouché. A reply to a criticism of M. de Sparre on former paper by the author.-The thickness of transparent sheets of iron: L. Houllevigue. After trying unsuccessfully various methods for estimating the thickness of thin films of iron, a colorimetric estimation with sulphocyanide was found to give trustworthy results. The transparency (T) of these films was determined before dissolving in acid for the colorimetric test, and for films varying in thickness from 0.024 to 0.056 milligram per square centimetre the thickness was found to be a linear function of log T. This curve being established, the thickness of any given film could be quickly determined by the photometer.-The automatic registration of atmospheric ionisation : Charles Nordmann. The charge introduced by the ions is removed from the condenser plate by falling drops of water, the constancy of flow being secured by a Marriotte's bottle. The deviations of the electrometer in the arrangement described, a diagram of which is given, are proportional to the number of ions per unit volume of the gas.-On the heat given off by paraffin submitted to the action of a rotating electrostatic field of high frequency: Ch. Eug. Guye and P. Denso.-On a new reaction of aldehydes and the isomerism of their oxides: A. Conduché. The aldehyde is added to a dilute aqueous solution containing equimolecular proportions of hydroxylamine hydrochloride and potassium cyanate. Well crystallised compounds separate out, the melting points of which characterise the aldehyde. The discussion of the composition of these compounds throws light on the constitution of the isomeric aldoximes. No corresponding compounds are obtained when a ketone is substituted for the aldehyde in the reaction.-The action of hydrocyanic acid on epiethyline: M. Lespieau. The nitrile C,H,.O.CH,—CH(OH)—CH,.CN is obtained in this reaction, and the preparation and properties of several substances derived from this are described. On the non-existence of two stereoisomeric ethyl dioximidobutyrates: L. Bouveault and A. Wahl. The supposed existence of two stereoisomers indicated by Hantzsch and bv Nussberger is shown to be erroneous.-On the transformation of amylocellulose into starch: Eugène Roux.-On the electrolysis of organic acids by means of the alternating current: André Brochet and Joseph Petit. The electrolysis of formic and oxalic acids can be easily effected with the alternating current; the results are the same as with the direct current, but the yields are much higher. On the phosphorescence of phosphorus: E. Jungfleisch. It is shown that an inert gas, saturated with the vapour of phosphorus, contains an extremely small weight of phosphorus, the oxidation of which gives rise to scarcely appreciable light effects. The author regards his experiments as proving that a lower volatile oxide is first produced, and that it is the oxidation of this which gives rise to the luminous phenomena.-On isodimorphism: Frédéric Wallerant. On the extension of the alkaline rocks in the basin of Aouache: H. Arsandaux. Two species of Dalbergia in Madagascar produ

ing a variety of ebony wood: Henri Jumelle. On the biology of the Saprolegnia: Paul Dop.-The utilisation of the essential oils in the etiolated plant: Eug. Charabot and Alex. Hébert. It is shown that in the absence of light the plant is capable of consuming the essential oil which it contains, especially the terpenic compounds.-The relations between Bougainvillia fruticosa and Bougainvillia ramosa: Paul Hallez. The author regards these as one and the same species, the one belonging to calm water, the other to rough water, the slight difference between the two being due to this difference in the surroundings. Experimental researches on the relations between arterial pressure and the amounts of chloroform absorbed : J. Tissot. In the case of subjects under chloroform the examination of the arterial pressure gives indications of approaching trouble earlier than the respiratory modifications, the latter only appearing when the dangerous condition is already set up.-A comparative study of the auto-conducting cage and the condensing couch in the treatment of arterial hypertension by d'Arsonvalisation: A. Moutier and A. Challamel. The results obtained with the solenoid are better than with the couch, the commonly accepted view that the two are equivalent being erroneous. The action of radium on the torpedo fish: Maurice Mendelssohn.-On the tectonic of the region north of the Montagne Noire: Jules Bergeron.—The daily variation of temperature in the upper regions of the atmosphere: L. Teisserenc de Bort.

DIARY OF SOCIETIES.

THURSDAY, FEBRUARY 23.

ROYAL SOCIETY, at 4.30.-On some New Species of Lagenostoma; a Type of Pteridospermous Seed from the Coal-measures: E. A. Newell Arber.On a New Rhabdosphere: G. Murray, F.R.S.-Two Cases of Trichromic Vision: Dr. F. W. Edridge-Green. -On Changes observable in the Liver Cells during Digestion, and their Relation to Hepatic Secretion: Prof. E. Wace Carlier.-The Colour-Physiology of the Higher Crustacea Part III.: F. Keeble and Dr. F. W. Gamble.Phosphorescence caused by the Beta and Gamma Rays of Radium. Part II.-G. T. Beilby.

ROYAL INSTITUTION, at 5.-Recent Work of the Geological Survey: Prof. J. J. H. Teall, F.R.S.'

INSTITUTION OF ELECTRICAL ENGINEERS, at 8.-Continuation of Discussion:-The Value of Overhead Mains for Electric Distribution in the United Kingdom: G. L. Addenbrooke.

FRIDAY, FEBRUARY 24

ROVAL INSTITUTION, at 9.-Fungi: Prof. H. Marshall Ward, F.R.S. PHYSICAL SOCIETY, at 5.-On the Curvature Method of teaching Geometrical Optics: Dr. C. V. Drysdale. - Exhibition of Dr. Meisling's Colour Patch Apparatus: R. J. Sowter.-A Method of illustrating the Laws of the Simple Pendulum, and an Exhibition of String Models of Optical Systems: J. Schofield.

INSTITUTION OF CIVIL ENGINEERS, at 8.-Morecambe Sewerage : Method of laying a 15-inch Cast-iron Sewer under the London and NorthWestern Railway: F. D. Flint. The Reconstruction of Bow Bridge over the River Lea: H. M. Rootham.

SATURDAY, FEBRUARY 25.

ROYAL INSTITUTION, at 3.-Archæology: D. G. Hogarth.
THE ESSEX FIELD CLUB, at 6. 30 (at the Essex Museum of Natural History,
Stratford).-Straw Plait; a Lost Essex Industry, I.: Chalkley Gould.-
Family and Life of Gilberd, of Colchester: Prof. Silvanus P. Thompson,
F.R.S.-Revised List of the Hymenomycetal Fungi of Essex: Dr.
M. C. Cooke and George Massee.

MONDAY, FEBRUARY 27.
ROVAL GEOGRAPHICAL SOCIETY, at 8.30.-The Scientific Results of the
National Antarctic Expedition: Capt. R. F. Scott, C. V.O., R N.
SOCIETY OF ARTS, at 8.-Internal Combustion Engines: Dugald Clerk.
INSTITUTE OF ACTUARIES, at 5.-Changes in Pure Premium Policy-
Values consequent upon Variations in the Rate of Interest or the Rate of
Mortality, or upon the Introduction of the Rate of Discontinuance :
G. J. Lidstone.

TUESDAY, FEBRUARY 28.

THURSDAY, MARCH 2.

ROYAL SOCIETY, at 4.30.-Probable Papers: Further Researches on the
Temperature Classification of Stars. No. 2: Sir Norman Lockyer,
K.C.B., F.R.S.-On the Radio-active Minerals: Hon. R. J. Strutt-
Atmospheric Electricity in High Latitudes: G. C. Simpson.-On the
Spectrum of Silicon, with a Note on the Spectrum of Fluorine: J. Lust
On the Electric Resistance to the Motion of a Charged Sphere in
Free Space or in a Field of Force: G. W Walker.
CHEMICAL SOCIETY, at 8.-The Latent Heat of Evaporation of Benzene
and some other Compounds: J. Campbell Brown.-The Relation between
Natural and Synthetic Glycerylphosphoric Acids: F. B Power and
F. Tutin.-The Reduction of Isophthalic Acid: W. H. Perkin, jun, and
S. S. Pickles.-The Transmutation of Geometrical Isomers: A. W
Stewart.

ROYAL INSTITUTION, at 5.-Recent Astronomical Progress: Prof. H. H
Turner, F.R.S.
RÖNTGEN SOCIETY, at 8.15.-A discussion on "The Necessity of Accurate
Measurement in X-ray and High Frequency Work," opened by D:
W. D. Butcher.

CIVIL AND MECHANICAL ENGINEErs' Society, at 8.-Engineering Expert
Evidence J. F. Reade.
LINNEAN SOCIETY, at 8.-Zoological Nomenclature; International Rules
and Others (to be followed by a discussion): Rev. T. R. R. Stebbing.
F.R.S.-Biscayan Plankton. Part IV. The Thaliacea: Dr. G. Herbert
INSTITUTION OF ELECTRICAL ENGINEERS, at 8.-Type-setting by Tele
graph D. Murray.

Fowler.

I.

ROVAL INSTITUTION, at 5.-Some Recent Biometric Studies: Prof. K.
Pearson, F.R.S.
SOCIETY OF ARTS, at 4.30.-The Manufactures of Greater Britain.
Canada: C. F. Just.
INSTITUTION OF CIVIL ENGINEERS, at 8.-Surface-Condensing Plants,
and the Value of the Vacuum produced: R. W. Allen.

WEDNESDAY, MARCH 1.

SOCIETY OF PUBLIC ANALYSTS, at 8.-The Estimation of Oxygen in
Copper: S. Dickson.-(1) Some Conditions affecting the Ether Value
of Brandies; (2) The Determination of Higher Alcohols in Spirits. I.:
Dr. Philip Schidrowitz and F. Kaye.
ENTOMOLOGICAL SOCIETY, at 8.-New Species of Diurnal Lepidoptera

from Northern Rhodesia: Herbert Druce and Hamilton H. Druce.-— On Three Remarkable New Genera of Microlepidoptera: Sir George F. Hampson, Bart.

CRITICAL SOCIETY OF UNIVERSITY COLLEGE (Gower Street, W.C). at 5. --Evolution and Speculation: Sir Frederick Pollock, Bart. Visitors invited.

Studies in Eugenics

The Absorption of Light by the Atmosphere .. 402
John Hunter and his Influence on Scientific
Progress. By John Tweedy
University and Educational Intelligence
Societies and Academies

Diary of Societies

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