November 23, 1905 J 



NA TV RE 



change through heredity is a process requiring very long 

 periods of time, so increase of natural ability by selection 

 .1 variations must remain, on the whole, inconsiderable, 

 (c) That the more important factor is individual acquire- 

 ment or education. The great output of genius during 

 the Athenian and Renaissance periods is to be explained, 

 not 'in terms of natural ability, but as arising from ex- 

 ceptional opportunity, (d) That the one practicable method 

 of improving the racial average of natural ability is by 

 the elimination of dearly degenerate- types. 



Challenger Society, October 25. — Mr. E. W. L. Hult 

 in the chair. — Charts illustrating the physical conditions 

 in the English Channel during 1903 and 1004: Dr. E. J. 

 Allen and D. J. Matthews. The observations, which 

 were conducted from the Plymouth laboratory of the 

 Marine Biological Association as a centre, had been made 

 by the association's steamers Huxley and Oithona, by 

 ocean-going liners and cross-Channel steamers, and at 

 lightships and lighthouses. They extended from about 

 Ihingeness to Cape Finisterre, and showed the north- 

 easterly movement of oceanic water of high salinity and 

 temperature, the southerly movement of water of low 

 salinity from the Irish Sea, and the varying effects of 

 these movements on the waters of the English Channel in 

 different months. 



Royal Astronomic U Society, November 10. — Mr. W. II. 

 Maw, president, in the chair. — Observations of the sixth 

 and seventh satellites of Jupiter, from photographs taken 

 at the Royal Observatory, Greenwich, with the 30-inch 

 reflector of the Thompson equatorial : Astronomer Royal. 

 The photographs were shown on the screen, with diagrams 

 to illustrate the orbits of the satellites. — Observations of 

 the satellite of Neptune, from photographs taken at the 

 Roval Observatory, Greenwich, with the 21. -inch refractor: 

 Astronomer Royal. — Expedition to Vinaroz, en I he east 

 coast of Spain, to observe the total solar eclipse of August 

 last : Father Cortie. — Eclipse expedition to Burgos : Mr. 

 Thwaites. — Eclipse expedition to Labrador : Mr. 

 Maunder. — Photograph of the partial phase of the recent 

 eclipse showing distinctly the entire disc of the moon : 

 Mr. Saunder. — (1) Secular acceleration of the earth's 

 orbital motion ; (2) Ptolemaic eclipses of the ntocn as 

 reci rded in the Almagest : Mr. Cowell. In a paper already 

 printed the author showed that the ancient solar ellipsis 

 are satisfied by adopting the following secular terms : — 

 It) in the distance of the moon from the node +4"-4, and 

 (2) in the distance of the moon from the sun 4- 6" -8. He 

 now showed that these conclusions are supported by the 

 eclipses of the moon as given in the Almagest. Mr. Cowell 

 considered that a secular acceleration of the earth's orbital 

 motion does not contravene gravitational theory, as Prof. 

 \< wromb had suggested, since it might be ascribed to the 

 resistance of the ether. — Other papers were taken as read. 



Physical Society, Noven ber 10. — Dr. C. Chree, F. R.S , 

 vice-president, in the chair. — The question of temperature 

 and efficiency of thermal radiation : J. Swinburne. It has 

 long been known that various surfaces have different 

 emissivities, and it is generally held that at a given 

 temperature some bodies radiate a larger percentage of 

 their total radiation in the form of light. This view is 

 largely based on some experiments bv Evans and 

 Bottomley, both of whom, the author remarks, make the 

 same slip in confusing difference of emissivitv with differ- 

 ence of efficiency at the same temperature. It is urged 

 that a body A at the same temperature as B cannot give 

 out radiation corresponding to a higher temperature of B, 

 for if it could, and A and B were enclosed in a perfectly 

 reflecting space, A wi ulel heat B to a higher temperature 

 than A. — Note on constant-deviation prisms : T. H. 

 Blakesley. It appears that any prism of three faces can 

 he made to give a spectrum in which the light, that 

 occupies the centre of the field of view of the telescope at 

 any moment, has undergone passage through the two 

 refracting surfaces of the prism in such a way that its 

 original angle of incidence is equal to its final angle of 

 emergence. This condition, which in the ordinary employ- 

 ment of the prism is associated with minimum deviation, 

 must be described as isogonal passage, the property which 

 has the minimum value being not the deviation, but the 



NO. 1882, VOL. 73] 



rate of passage across the field of view for a given motion 

 if the prism, to which alone in these instruments motion 

 has to be given to bring different parts of the spectrum 

 into the fiefd, the telescope and collimator both remaining 

 fixed. If any triangle having the angles a, $, 7 is adopted 

 as the shape of a prism, the telescope must be set to make 

 one of these angles, say 7, with the line of the collimator. 

 Then the prism being placed in the region between them, 

 a posit,, n can be found so that arij ray selected will be 

 refracted through one of the sides containing the angle 7, 

 reflected at the side opposite 7, and linalh refracted 

 through the remaining side containing 7. On emergence 

 it will be parallel to the telescope, and its passage through 

 the refracting faces will be isogonal. The prism will 

 affect the light to the same degree as_ one used in the 

 ordinary way, of refracting angle i«-a, would do. The 

 sine of the angle of original incidence is equal to 

 M . sin (/3-a)/2 for every ra\ occupying the centre of the 

 p.eld 1 f view. If the prism is turned over, but the same 

 angle 7 employed, the telescope will remain unaltered, but 

 the spectrum will run in an opposite direction to the 

 first. Mr. Blakesley showed the case of two prisms in 

 which the spectra ran in different directions. The top 

 prism was slightly tilted by the insertion of a small 

 piece of silver paper between the prisms. By this means 

 one of the spectra was shifted upwards by a small 

 amount, and one could see in the telescope a band, at top 

 and bottom, of the component colours, and in the centre 

 a band of the resulting colours. It was suggested that 

 spectroscopes on this plan could be advantageously 

 employed in measuring the motion in the line of sight of 

 heavenly bodies, as a line brought into coincidence with 

 itself for a terrestrial source in the two spectra would, in 

 the case of such motion, split up into two moving different 

 ways in the field of view. It was also explained how such 

 prisms could be placed in trains for increased dispersion. 



Royal Meteorological Society, November 15. — Mr. 

 Richard Bentley, president, in the chair. — The rainstorm 

 of August 24 to 26 in counties Dublin and Wicklow : 

 Sir John W. Moore. The atmospheric disturbance which 

 caused the torrential rainfall was near the shores of Kerry 

 and Cornwall on August 24, and the next morning it was 

 near the Scilly Islands. Thence it travelled slowly north- 

 wards up St. George's Channel, its centre passing near 

 Dublin early on the morning of August 20. At this time 

 the system suddenly changed its course, crossing the 

 channel eastwards to Wales, and finally passing over 

 central England and out to sea at the mouth of the Humber 

 in a ncrth-easterly direction. It appears that the rainfall 

 on August 25 exceeded 3 inches at all stations in the 

 counties Dublin and Wicklow, while it rose above 4 inches, 

 and even 5 inches, at stations near the Dublin and Wicklow 

 mountains. Sir John Moore is of opinion that this remark- 

 able downpour was brought about by the cooperation of 

 the following factors: — (1) a chill antecedent to the arrival 

 of the rain-bearing depression; (2) the slow progress of 

 the depression ; (3) the fact that the counties Wicklow and 

 Dublin lay to the westward of the cyclonic centre, and so 

 received its north-easterly and northerly winds ; and (4) the 

 physical configuration of those counties and their coast 

 line. As the result of this remarkable rainstorm a de- 

 structive flood occurred ever the low-lying parts of the 

 Bray urban district near the mouth of the Bray River. 

 At Little Bray the water rose to a height of 4 feet in the 

 streets, flooding houses, destroving domestic animals and 

 fowls, wrecking furniture, and covering floors, yards, and 

 gardens with a thick alluvial deposit. — The aquameter : Dr. 

 W. B. Newton. This is a new instrument for measuring 

 accurately the amount of aqueous vapour present in the 

 atmosphere. 



Pmjis. 

 Academy of Sciences, November 13 — M. Tionst in the 

 chair. — Nitrates and nitrites .is manure : Th. Ccnloesing, 

 jun. Nitrate of calcium is now produced by electrical 

 means from the air, and the salt thus obtained contains 

 nitrite. It was desirable to ascertain whether the calcium 

 nitrate is equivalent for manurial purposes to the sodium 

 nitrate in ordinary use. and also whether the nitrite was 

 in any way prejudicial. Cultivation experiments showed 

 that the two nitrates were equivalent, and that the presence 



