August 15, 1907J 



NA TURE 



407 



(i) The values found are as follows, the accuracy being 

 within about 3 per cent. : 



Hard rays 

 6 '3 to 8 '3 X 10'' 

 6' I to 8 'OX 10'' 



6'4 to S'l X 10" 

 6'2 to 8-1 X 10' 



(3) The velocity of the fastest electrons emitted from each 

 metal is completely independent of the intensity of the 

 primiry rays, but increases with the hardness of the tube. 



(4) The velocity decreases with the atomic weight, the 

 difference between the speed of the fastest electron with 

 hard rays and that with soft rays being practically tho 

 same for the various metals, if the variation in hardness of 

 the rays is the same. 



(5) A minimum velocity is necessary to enable the electron 

 to emerge, and the minimum velocity is nearly the same in 

 the different metals. 



(6) The number of electrons given off decreases with 

 decreasing intensity of the rays, as well as with increasing 

 hardness. 



(7"! The number emitted also decreases with decreasing 

 atomic weight and density. 



(S) The conclusion is drawn from calculation and dis- 

 cussion of other theories that the most probable theorv 

 is that of atomic disintegration. It is shown that the 

 velocity of the emitted electron is too great to be that 

 acquired under the influence of the electric force in the 

 X-ray pulse. The other theory of ejection is discussed 

 and objections to it pointed out. A possible explanation 

 is given of the increase of the velocity with increasing 

 hardness of the rays, and tliis fact is shown not to be 

 inconsistent with the disintegration theory. 



Edixel'kgh. 

 Royal Society, July 8. — Dr. Robert Munro, vice- 

 president, in the chair. — The plant retnains in the Scottish 

 peat mosses, part iii. : F. J. Lewis. The third part dealt 

 with the peat mosses of the east and north-west Highlands, 

 Shetland, and the Outer Hebrides. All the Scottish peat 

 mosses show a definite succession of plant remains. The 

 oldest in the south of Scotland and the Shetland Islands 

 have an .Arctic plant bed at the base. This is succeeded 

 by a forest of birch, hazel, and alder containing temperate 

 plants, h. second -Arctic plant bed occurs above the lower 

 forest, and is overlaid in all districts except the Hebrides, 

 Cape Wrath, and the Shetland Islands by the upper forest, 

 covered by several feet of peat bog plants. While it is 

 difficult to reconcile -the several stages in the peat with 

 the theory of a single glaciation, the peat beds as a whole 

 agree very closely with the scheme of classification proposed 

 by Geikle in " The Great Ice Age." — Note on the abyssal 

 temperature of fresh-water lakes : E. M. Wedderburn. 

 Observed distributions of lake temperatures were brought 

 forward as illustrations of the author's view that thi- sur- 

 face current set up by wind action produces a back current 

 at a moderate depth, with a slow movement of the bottom 

 layers parallel to the surface current. — The .action of 

 sodium ethylate on trichloromethylsulphonic chloride : Prof. 

 A. Crum Bro>wn and T. F. Cowie. — A hybrid between 

 Prejvalskv's horse and a Highland pony: Prof. J. C. 

 Ewart. In most respects the hybrid differed little 

 from an ordinary cross-bred pony. In its mane, however. 

 it afforded striking evidence of its mixed origin. The front 

 part of the mane projected forward, but failed to form a 

 forelock. The rest consisted of hairs which were either 

 erect or arched outward, some falling towards the right, 

 others towards the left. The experiment gave further 

 evidence in favour of the theory that our modern horses 

 are descended from several distinct stocks, of which the 

 Prejvalskv horse is one. — .A note on a reflected mirage : 

 Dr. C. Tt. Knott. This was an account of a curious 

 mirage observed in South .Africa by members of a cadet 

 corps who were camping out to the south-east of Wor- 

 cester. With the town at their back the observers saw 

 about four miles off. apparently on the back of the river, 

 a recognisable image of the town itself. — The svstem 



sulphur-iodine : Prof. .Alex. Smith and C. M. Carson. 



The freezing points of mixtures of iodine and sulphur show 

 that these elements neither combine chemically nor form 

 solid solutions. — Precipitated sulphur : Prof. Alex. Smith 

 and R. H. Brownlee. Sulphur precipitated from poly- 

 sulphides by means of acids is almost wholly composed of 

 soluble rhombic sulphur. The fluid droplets of which the 

 precipitate is at first composed crystallise to monoclinic 

 sulphur, and the masses of the latter afterwards turn into 

 rhombic sulphur without change in their spherical form. 

 The sulphur precipitated from sodium thiosulphate by means 

 of acids is wholly soluble when acetic acid is used. With 

 hydrochloric acid the precipitate is viscous. The amount 

 of insoluble sulphur is proportional to the concentration of 

 the acid, and varies from 6 per cent, to 96 per cent. — 

 Preliminary note on the optical rotations (throughout the 

 spectrum), the electrical conductivities, and the densities of 

 mixtures of sodium-potassium-tartrate and ammonium 

 tuolybdate in aqueous solutions. The essential feature of the 

 method lay in the measurements being made for all kinds 

 of light. Interesting results were obtained with respect to 

 the influence of non-active substances when added to active 

 solutions. 



July 15. — Dr. Robert Munro, vice-president, in the chair. 

 — The Pycnogonida of the Scottish National Antarctic Ex- 

 pedition : T. V. Hodg^son. The main interest of the 

 Scotia collection lay in the problem of distribution to which 

 it gave rise. Antarctic and sub-.Antarctic regions were dis- 

 tinguished, being separated provisionally by the sixtieth 

 parallel south. Of the fifteen species recorded from the 

 Scotia the most striking was the Dccolojioda aiistralis, 

 a species discovered and accurately described some 

 seventy years ago, but forgotten, and when first noticed 

 despised as a monstrosity or as a sample of defective work. 

 — The marine mollusca of the Scottish National Antarctic 

 Expedition : J. C. Meivill and R. Standen. The col- 

 lection is interesting because of the number of deep-sea 

 forms brought for the first time from unusual depths, and 

 because of the extension of the geographical range of cer- 

 tain species already known. A second example of the 

 hitherto unique Giiivillea alahastrina, Watson, was dredged 

 from a station not far from the original Challenger locality. 

 Of the ninety-five species described, the gastropods claim 

 fifty-nine with eleven new species, the scaphopods two 

 with one new species, and the pclecypods thirty-four with 

 nine new forms. — Preliminary note on the internal structure 

 of SigiUaria mamillaris, Brongt., and Sigilhiria sciitellata. 

 Brongt. ; and description of a new species of Lepidodendron 

 (L. "pettycurense) from Pettycur : Robert Kidston. — 

 The periods of the elliptic functions of Weierstrass : R. T. A. 

 innes. The paper gave a new method of calculating the 

 periods when the invariants of the cubic were given. — 

 Hydrachnidre collected by the Lake .Survey : W. William- 

 son. Among the various forms described there was a 

 species of Whitfeldtia, which until now had not been found 

 outside Norway. — Degenerations following experimentaf 

 lesions in the motor cortex of the monkey : Drs. W. A. 

 Jolly and Sutherland Simpson. Lesions were made in 

 the motor cortex of the monkey, Macacus rhesus, involving 

 portions of the leg, arm, and face areas. The fibres of 

 the pyramidal tract arising from these areas were traced 

 by the method of secondary degeneration from their source- 

 to their termination. It was foimd that the fibres from 

 these areas begin to intermingle soon after they leave the 

 motor cortex. In the internal capsule there is already a 

 good deal of overlapping, and this is more marked still in 

 the pes pedunculi. Throughout the pons, medulla oblongata,, 

 and spinal cord the intermixture is practically complete, 

 so that below the level of the mid-brain there is no localis- 

 ation or grouping of the fibres within the pyrainidal tract 

 as there is of the cells from which they take origin in the- 

 motor cortex. Above this level some localisation of fibres 

 does take place, but it is only partial, the degeneration 

 from one area encroaching upon that from the neighbour- 

 ing areas to a considerable extent. — Classification of 

 igneous rocks according to their chemical composition : 

 Dr. H. Warth. — Note on quaternion integrals : Dr. H. 

 Hermann. This was an improved demonstration of the- 

 generalised quaternion form of the theorems which include 

 those of Green, Gauss, and Stokes. 



NO. 1972 VOL. 76] 



