May 24, 1900] 



NATURE 



95 



Wilkinson ; and lineaE substitutions commutative with a given 



ilistitution, by Dr. L. E. Dickson. — Lieut. -Colonel Cunning- 



iiam, R.E., V.P., showed that numbers which are expressible 



in the two forms N = ^ -?'-^ = '^ "^ ---^ are always com- 

 ix a 

 posite, when /tv = /»''; and showed how to reduce them to 

 the forms N = X^ + yuvV* = X'^ + ^vY'^, the factorisation of which 

 is known from Euler's researches. 



Royal Meteorological Society, May 17. — Dr. C. Theodore 

 Williams, President, in the chair. — A paper was read on the 

 Wiltshire whirlwind of October i, 1899, which had been pre- 

 pared by the late Mr. G. J. Symons, F. R.S., a few days before 

 he was stricken down with paralysis. This whirlwind occurred 

 between 2 p.m. and 3 p.m., commencing near Middle Winter- 

 slow and travelling in a north-north-easterly direction. The 

 length of the damage was nearly twenty miles, but the average 

 breadth was only about ICX) yards; in this narrow track, how- 

 ever, buildings were blown down, trees were uprooted, and 

 objects were lifted and carried by the wind a considerable dis- 

 tance before they were deposited on the ground. Fortunately 

 the greater part of the district over which the whirlwind passed 

 was open Down, otherwise the damage and perhaps loss of life 

 would have been considerable. At Old Lodge, Salisbury, the 

 lifting power of the whirlwind was strikingly shown by several 

 wooden buildings being lifted up and dropped down several feet 

 north-west of their original position. At a place eighteen miles 

 from its origin the whirlwind came upon a rick of oats, a con- 

 siderable portion of which it carried right over the village of 

 Ham and deposited in a field more than a mile and a half away. 

 — A paper by Dr. Nils Ekholm, of Stockholm, was also read on 

 the variations of the climate of the geological and historical past 

 and their causes. In this the author attempts to apply the 

 results of physical, astronomical and meteorological research in 

 order to explain the secular changes of climate revealed by 

 geology and history. 



Dublin. 



Royal Dublin Society, February 21. — Prof. G. F. Fitz- 

 gerald, F.R.S., in the chair.— Prof. W. N. Hartley, F.R.S., 

 ommunicated his papers on the action of heat on the ab- 

 sorption spectra and chemical constitution of saline solutions, 

 ind on the occurrence of cyanogen compounds in coal-gas, 

 ind of the spectrum of cyanogen in that of the oxy-coal-gas 

 ilame. — Prof. E. J. McWeeney gave an account of the ! recently 

 demonstrated connection between mosquitoes and malaria, with 

 a lantern demonstration of the life-history of the former. — Prof. 

 T. Johnson communicated a note on Sclerotium disease of 

 Jerusalem artichoke grown at Greystones, county of Wicklow. 



March 21.— Dr. F. T. Trouton, F.R.S., in the chair.— Dr. 

 G. H. Pethebridge read a paper, entitled "Contributions to the 

 knowledge of the action of inorganic salts on the structure and 

 development of plants." — Mr. R. J. Moss (in the absence of 

 Dr.W. E. Adeney) communicated a paper, by Prof. E. A. Letts 

 and Messrs. Blake, Caldwell and Hawthorne, on the nature 

 and speed of the chemical changes which occur in mixtures of 

 sewage and sea- water. — Prof. J. Joly read a paper on the theory 

 of the order of formation of silicates in igneous rocks, which was 

 ^illustrated by a diagram (see p. 84). 



April 25. — Prof. J. Emerson Reynolds, F.R.S., in the chair. 



-Prof. J. Emerson Reynolds, P\R.S., read a paper on recent 



lalyses of the Dublin gas supply, and observations thereon. — 

 *rof. G. A. J. Cole communicated a paper by himself and Mr. 

 ^. A. Cunningham on certain rocks styled '* felstones," occur- 

 " ig as dykes in the county of Donegal. 



Edinburgh. 



Royal Society, May 7.— Sir Arthur Mitchell, K.C.B., in the 



liair. — Mr. JohnAitken, F.R.S., read a paper on the dynamics 



Fcyclones and anticyclones, Part ii. , which wais illustrated by an 



jenious experiment showing the production of vortex columns 



the air. Over the upper metal surface of a flat box through 



^hich steam was blown was spread a sheet of brown paper 



ioroughly soaked with hot water. A steady gentle blast of 



was driven across this steaming surface by means of a rotating 



; and when a barrier was intercepted so as to cut off half of 



le surface from the direct effect of the blast, a succession of 



rhirls was started at the boundary between the sheltered and 



sheltered parts of the surface. These whirls were plainly 



sible in the columns of rotating cloud, and showed on a small 



NO. 1595, VOL. 62] 



scale some of the characteristics of cyclones. According to Mr. 

 Aitken's mode of looking at the phenomenon, the blast of air 

 produced by the fan is analogous to the anticyclonic marginal 

 wind which is regarded as driving the cyclone. The relations be- 

 tween the upper and lower currents in a cyclonic movement 

 were also illustrated in the experiment. — Mr. R, C. Punnett 

 communicated a paper on certain Nemerteans from Singapore, 

 in which several facts of morphological interest were brought 

 to light, notably the presence, in one species, of ducts placing 

 the anterior portion of the alimentary canal in communica- 

 tion with the excretory system, and so with the exterior ; and 

 the different features shown in the termination of the lateral 

 nerve-cords in a single genus where there might be a commis- 

 sure either above or below the rectum, or else no commissure 

 at all. — Mr. R. T. Omond, in a paper on the reduction to sea- 

 level of the Ben Nevis barometer, pointed out that, using the 

 ordinary reduction formula, we get an appreciable difference be- 

 tween the observed sea-level pressure at Fort William and the 

 reduced Ben Nevis reading. Leaving out of account all cases 

 in which strong winds were blowing, Mr. Omond had worked 

 out in detail the hourly readings for a period of time extending 

 over six years, and gave reasons for his belief that the dis- 

 crepancy noted above was due to a false estimate of the average 

 temperature of the air between Fort William and Ben Nevis. 

 This average was not the mean of the bottom and top tem- 

 peratures. 



Mathematical Society, May 11. — Mr. Muirhead, Presi- 

 dent, in the chair. — A theorem in continued fractions (Prof. 

 Steggall), on certain elementary inequality theorems (Prof. 

 Gibson), note sur un probleme de geometrie (Mons. Ed. Col- 

 lignon) ; communicated by Dr. Mackay. 



Paris. 

 Academy of Sciences, May 14. — M. Maurice Levy in 

 the chair. — On a zenitho-nadiral apparatus designed to measure 

 the zenithal distances of stars near the zenith, by M. A. Cornu. 

 In front of a horizontal telescope carrying a wire micrometer is 

 placed a special arrangement of two mirrors making an angle 

 with each other of 90°. Four images can be seen simultaneously, 

 that of the star near the zenith, the cross wires, the reflection of 

 these wires in the mercury bath, and the image of the wires 

 from the special reflector. When the image of the movable 

 wire coincides with its reflected image from the mercury bath, 

 the nadiro-zenithal image of this wire passes through the zenith, 

 whatever may be the deviation from a right angle of the angle 

 between the mirrors. The arrangement possesses important 

 advantages over the methods at present in use. — Remarks 

 on a meteor which fell in Bolivia on November 20, 1899, 

 by the French Charge d' Affaires at La Paz.— On divergent 

 series, by M. Le Roy. — On the representation of non- 

 uniform functions, by M. L. Desaint. — On a modifi- 

 cation which metallic surfaces undergo when submitted 

 to light, by M. H. Buisson. Under the influence of light, the 

 metallic surface changes its state as measured by the rate at 

 which it loses a charge of electricity, this change not being per- 

 manent but gradually disappearing when the radiant energy is 

 cut off. — On the thermoelectric properties of some alloys, by 

 M. Emile Steinmann. The alloys studied were ten nickel 

 steels, four samples of platino-iridium, three of aluminium 

 bronze, five telegraphic bronzes, five bra.sses, and four of 

 German silver, at temperatures ranging from 0° to 260° C. In 

 the binary alloys the observed electromotive forces are arranged 

 in the order of magnitude of one of the components, but no 

 simple relation could be deduced between the electromotive 

 force and chemical composition in the case of nickel steel or of 

 ternary alloys. — Duplex and diplex transmission by electric 

 waves, by M. Albert Turpain.— Experiments in wireless tele- 

 graphy from a free balloon, by MM. J. Vallot, J. Lecarme 

 and L. Lecarme. It was found to be possible to transmit 

 messages to the balloon without an earth wire, even up 

 to a distance of six kilometres and a vertical height of 

 800 metres. — An arrangement designed to prevent the inter- 

 ception of despatches in wireless telegraphy, by M. D. Tommasi. 

 — On the hydrated calcium peroxides, by M. de Forcrand. A 

 thermochemical paper.— On the allotropic transformations of 

 the alloys of iron and nickel, by M. L. Dumas.— Preparation 

 of some aluminium compounds and of the corresponding hydro- 

 gen derivatives, by M. Fonzes-Diacon. Details are given of 

 the preparation of aluminium sulphide, selenide, phosphide, 



