February 23, 1899] 



NA rURE 



40; 



by Darboux ("Theorie des Surfaces ''), we are led lo a type of 

 solution of V"V = o, which seems to be related to the forms 

 given by Prof. Forsyth in ihe A/esseii^er of Maihemattcs, 1897. 

 In the second part of the paper, Mr. Bromwich investigates this 

 solution and allied forms. — On the complete system of differ- 

 ential covariants of a single Pfaffian expression, and of a set of 

 Pfaftian expressions, by Mr. J. Brill ; and the figure of Jacobi 

 with respect to a linear system of hyperquadrics, by Prof. P. H. 

 Schoute. 



Royal Meteorological Society, February 15. — Mr. F. C. 

 Bayard, President, in the chair. — Mr. E. Mawley read his 

 annual report on the phenological observations, and stated that 

 the weather of the past year, taken as a whole, had been 

 throughout the British Isles very warm and dry. Wild plants 

 blossomed much in advance of their average dates until about 

 the end of March, but after that time until the close of the 

 flowering season they were mostly late in coming into bloom. 

 Favoured by the rains in May, the crop of hay was everywhere 

 a remarkably heavy one, but the long drought which followed 

 dried up the pastures and caused a scanty yield of roots. The 

 dry season suited the cereals .admirably, and especially the 

 wheat, of which there was a very abundant crop. The yield of 

 barley was nearly as exceptional, while that of oats, except in the 

 northeast of England, and in Scotland, was also unusually good. 

 There was a splendid crop of potatoes in Ireland and in parts of 

 Scotland, but elsewhere the yield was on the whole moderate. 

 Apples, pears and plums flowered abundantly, but adverse 

 weather conditions, and the dry subsoil in the spring, caused an 

 irregular "set" of fruit ; sothat in all parts of the kingdom these 

 crops were, as a rule, below average. On the other hand, there 

 were good crops of all the smaller fruits. — A paper by Prof. W. 

 M. Davis, of Harvard University, U. S., on the circulation of 

 the atmosphere, was read by the Secretary. The author said 

 that although the circulation of the atmosphere is one of 

 the earliest and one of the latest problems of meteorology, its 

 treatment is ordinarily inadequate, inasmuch as the serious 

 student seldom gains from the text-books in current use a 

 comprehensive view of the great problem. After giving a brief 

 historical development of the subject, the author went more 

 particularly into the question of the outflowing polar winds, 

 especially in the Antarctic regions. He called attention to the 

 remarks made by Dr. Buchan at the conference on the 

 "Scientific advantages of an Antarctic expedition," held at 

 the Royal Society last year, and maintained that Prof. W. 

 F-errel's views on the circulation of the atmosphere, so far as 

 they touch Antarctic winds and pressure, had been misunder- 

 stood by Dr. Buchan. Prof. Davis said that it must certainly be 

 clear to every physical meteorologist, that the conventional 

 circulation of the atmosphere, as ordinarily stated, was seriously 

 incompetent, for the most striking features in the distribution 

 of atmospheric pressure are not accounted for by it. As long .as 

 the effect of the winds in modifying the distribution of pressure 

 is left out of consideration, no broad understanding of atmo- 

 spheric processes can be reached. 



Camhriim;e. 

 Philosophical Society, January 23. — Mr. J. Larmor, 

 President, in the chair.— On the formation of clouds with 

 ozone, by J. S. Townsend. The clouds which are formed when 

 oxygen containing ozone is passed through a solution of potas- 

 sium iodide, or sodium metabisulphite, are treated of in this 

 paper. Experiments were described which showed that the 

 formation of these clouds is due to the escape of iodine, or sul- 

 phur dioxide, from the solution. When oxygen containing small 

 quantities of iodine vapour or .sulphur dioxide is passed into a 

 flask containing ozone a cloud is immediately formed. The 

 cloud disappears when the gas in which it is suspended is dried, 

 and reappears again in the presence of moisture. — (a) Or. 

 detectors of radiant heat. (/•) On the .symbolic integration of 

 ol certain differential equations in quaternions, by H. C. 

 Pocklington. — On the motion of a charged ion in a magnetic 

 field, by Prof. J. J. Thomson. In this paper the motion of an 

 ion moving through a gas dense enough for viscosity to make 

 the velocity of the ion proportional to the force acting upon it 

 is discussed. If H is the magnetic force, F the electric force, 

 9 the angle between II and F, -■„ the velocity acquired by the 

 ion under unit potential gradient, it is shown that the velocity 

 of the ion at any point will have a component proportional to F 

 along the line of electric force, a component proportional to 

 Hz'oF sin e along the line at right angles to H and F, and a 



NO. 1530, VOL. 59] 



component proportional to H'h'^'V cos 8 along the line of mag- 

 netic force. The relative importance of the three components 

 depends upon the value of Wva ; if this is large, the ions follow 

 the lines of magnetic force ; if it is small, they follow the lines 

 of electric force, while in intermediate cases they pursue a 

 spiral path. Thus if we suppo.se the magnetic force to l)e 

 constant, and consider two dift'erent kinds of ions moving with 

 different speeds under unit potential gradient, the more quickly 

 moving ions may travel along the lines of magnetic force, 

 while the more slowly moving ones may travel along spirals. 

 In the discharge of electricity through gases it has been found 

 whenever the velocity of the ions has been measured that the 

 velocity of the negative ion exceeds that of the positive. The 

 author has shown in a paper recently communicated 10 the 

 Philowphical Magazine \.\\2X this difference between the veloci- 

 ties of the positive and negative ions will account for many of 

 the remarkable differences between the appearances at the 

 kathode and anode of a discharge tube. The results given in 

 this paper .show that it will also account for the difference 

 between the behaviour of the negative glow and positive column 

 in a magnetic field. Pliicker showed that in strong magnetic 

 fields the negative glow follows the lines of magnetic force ; the 

 positive column, on the other hand, does not do so, but pursues a 

 more or less spiral path. This is what we should expect if the 

 negative glow marks the path of rapidily moving negative ions, 

 for which \iv„ is large ; in the positive column, on the other 

 hand, we have to do with more slowly moving positive ions 

 for which H?^ is not large enough to allow us to neglect the 

 components of the velocity along F and at right angles to F and 

 H in comparison with the velocity along H ; when this is the 

 case, the path of the ion is a spiral. 



Paris. 



Academy of Sciences, February 13.— M. van Tieghem in 

 the chair. — Notice on the life and work of the late Sir George 

 Henry Richards, correspondent in the Section of Geography and 

 Navigation, by M. Hatt. — On the heat of formation of an- 

 hydrous lime, starting from its elements, by M. Henri Moissan. 

 The author has taken advantage of the purity of the calcium 

 obtained by his methods to redetermine the heat of solution in 

 water. The heat of formation of lime thus obtained, 145 

 calories, is greater than that of the oxides of sodium, potassium, 

 and lithium ; and direct experiment .showed that this last metal 

 could be obtained by heating together lithia and calcium in a 

 vacuum. — On the mechanism of the thermal phenomena con- 

 nected with the elasticity of solid bodies, animate or inanimate, 

 by M. A. Chauveau. — On experimental typhoid infection in the 

 dog, by MM. R. Lepine and B. Lyonnet. After injection of a 

 virulent typhoid culture into the dog, the number of white 

 corpuscles in the blood was modified, some bacilli were excreted 

 by urine and bile, and the remaining bacilli appeared lo be 

 locali-sed in the liver and .spleen. After some days the blood 

 serum acquired the agglutinating power, but the animal pre- 

 served every appearance of health, although for some weeks 

 afterwards, living bacilli could be found in the liver and spleen. 



Contribution to the study of animal chlorophyll. The chloro- 

 phyll of the hepatic organ of Invertebrates, by MM. A. Dastre 

 and N. Floresco. The hepatic chlorophyll is of alimentary 

 origin ; it is a vegetable chlorophyll which is fixed in a very 

 persistent manner by the hepatic cells. — On an ancient fall of 

 shooting-stars, by M. D. Eginitis. A historical study of the 

 probable nature and identification of the asteroid swarm 

 mentioned as occurring in the reign of Constantine. The date 

 was prolfably the autumn of 752 : the swarm identical with 

 the .Vndroinides. — Comparative measures of chemical intensity 

 during the eclipse of the moon of December 27, 1898, by M. Th. 

 Mureux. The results of the photometric measurements of 

 luminous intensity, of chemical intensity, and of the theoretical 

 luminous intensity are plotted graphically. The three curves 

 do not coincide. — On a series of powers that are always 

 divergent, by M. S. Pincherle.— On the algebraic integrals, 

 of the equation of Riccati, by M. Leon Autonnc. — On 

 the elastic arch, by M. Georges Poisson. — On the propagation 

 of a gradual elongation in an clastic wire, by M. L. de la Rive. 

 — Influence of magnetism upon the he.at conductivity of iron, 

 by M. Desire Korda. It is found that the heat conductivity of 

 soft iron decreases in the direction of the magnetic lines of 

 force, but remains constant in the direction of equipotential 

 lines, independently of the sense of the magnetising force. — On 

 a particular case of electric oscillatiims produced by a Rubra- 



