94 



NA TURE 



{^Nov. 26, 18S5 



solution. Prof. G. Minchin pointed out the importance of per- 

 forming these and similar experiments upon tin in the dark, as, 

 by allowing light to fall upon the tin plate, a considerable 

 photo-electric effect would be obtained. Prof. Fleming insisted 

 upon the great importance of temperature corrections in all 

 experiments upon two-fluid cells. — On the law of the electro- 

 magnet and the law of the dynamo, by Prof. S. P. Thompson. 

 It cannot be said up to now that any particular law has been 

 generally accepted, giving the relation between the current in 

 the coils of an electro-magnet and the magnetism induced by it 

 in the core. Many empirical formulae have been given, most of 

 which are entirely wrong. One, however, recently enunciated 

 by Frohlich, gives a relation which agrees very closely with 

 observed values. This formula is — 



where m is the magnetic moment of the core, ;' the current, and 

 n and b constants depending upon the geometrical form of the 

 magnet, and the nature and previous history of the iron core. 

 Frohlich obtained this relation by experimenting with a series- 

 dynamo. It is purely empirical, but since it agrees so well 

 with the facts .as to give values for the magnetism of the core 

 agreeing almost within experimental error with those observed, 

 there is great probability of some law being at its base. And 

 this law Prof. Thompson believes to be one that was stated 

 years ago by Lamont : — "The magnetic permeability varies 

 with the quantity of magnetism the iron is capable of taking 

 up." This may,he expressed by the formula — 



dl 



Integrating which and expanding e-^-^ in powers of z — 

 Expanding Frcihlich's equation, in powers of?', we get — 



,„ = M.-^i + ^=- .1 



a K a a- ) 



If ki is not great these expressions will coincide in form very 

 closely, and the results lead Prof. Thompson to accept Lament's 

 expression as being that of a real physical law. Prof. Perry 

 suggested that Lamont's law gave good results from its being 

 an approximation to Weber's theory of induced magnetism, but 

 Prof. Thompson maintained that it represented observed facts 

 better than that theory, which, as developed by Maxwell, shows 

 a decided discontinuity in the process of magnetisation not 

 actually observed. Prof. Fleming remarked upon the similarity 

 of Frohlich's expression to that for the current through a volta- 

 meter ; the part <z -f- ^/ corresponding to the apparent resistance, 

 which may be considered in this case as the resistance to mag- 

 netisation of the core-air circuit, and which, like that of tlie 

 voltameter, varies with the current. 



Geological Society, November 4. — Prof. T. G. Bonney, 

 F.R.S., President, in the chair.— Dr. A. G. Nathorst, of 

 Stockholm, was elected a Foreign Correspondent of the 

 Society. — The following communications were read : — On the 

 premaxillaries and scalpriform teeth of a large extinct wombat 

 [Phascolomys cm~circstris, 0\v.), by Sir Richard Owen, K.C.B., 

 F. R. S. The specimen described in this paper is a cast from a 

 fossil discovered in a late exploration of the Wellington bone- 

 caves, and sent to the author with some other casts from the 

 same collection by the authorities of the Australian Museum, 

 Sydney, New South Wales. The fragments in question consist 

 of the premaxillary bones, containing a pair of scalpriform 

 incisors, 160 mm. (6J inches) long, measured along the outer 

 curve. The teeth and the fragments of bone in which they are 

 implanted were described in detail, and referred to the wombat 

 family. The animal to which they belonged must have been 

 somewhat larger than Phascolomys medim, Owen, but less than 

 the type of the sub-genus Phascolomys. The specific name is 

 suggested by the chief characters that distinguish the present 

 form from any hitherto known, recent or extinct. — On the 

 structure and classificatory position of some Madreporaria from 

 the secondary strata of England and South Wales, by Prof. P. 

 Martin Duncan, F.R.S. This paper consisted chiefly of a 

 criticism of the conclusions arrived at by Mr. R. F. Tomes in 

 various papers communicated to the Society. — On the Astrocanui: 



of the Sutton Stone of the Infra-Lias of South Wales, by Prof. 

 P. Martin Duncan, F.R.S. 



Anthropological Institute, November 10. — Mr. F. Gallon. 

 F.R.S., President, in the chair. — The following elections were 

 announced : — Prince Roland Bonaparte, Hon. Member ; Dr. 

 A. Asher, Dr. Alexander Bain, and Messrs. C. F. Clarke, J. 

 W. Crombie, T. H. Edwards, P. Norman, and E. Tregear, as 

 Ordinary Members. — This being the first meeting of the Sessiofi,,, 

 the President made some opening remarks, in the course of 

 which he congratulated the Institute upon the obvious increase 

 of public interest in the science of man. Besides the gratifying 

 facts that more new members are joining the Institute and that 

 the corresponding Section of the British Association was popu- 

 lar, there are such evidences as that the authorities of Trinity 

 College, Cambridge, have extended the tenure of one of their 

 Fellowships to enable its holder to pursue his anthropological 

 studies, and that at the meeting of the British Association at 

 Aberdeen it was the Rector of the University, Dr. Bain, who 

 contributed one of the most thoughtful of the anthropological 

 memoirs. Mr. Galton proceeded to insist upon the political 

 value of anthropology as the science that best qualifies us to 

 sympathise with other races and to regard them as kinsmen 

 rather than as aliens. — A paper containing a short account of 

 some experiments in testing the character of school children as 

 observers, was read by Mrs. Bryant. In these experiments an 

 attempt was made to read signs of character in an observer from 

 the manner in which he makes an observation and describes it 

 as made. From the written description of (i) a room, (2) a 

 picture, which the children experimented upon were first shown 

 and then required to describe, a rough diagnosis of their charac- 

 ter as observers can be made, and hence some idea of their 

 character generally is obtained, which, though very deficient in 

 precision and still more deficient in certainty, may have, never- 

 theless, a real practical value for educational and other purposes. 

 In the experiments made the most interesting points noticed 

 were: — (l) great variety in 'the proportions existing between 

 the sensational and intellectual factors of perception ; (2) the 

 occasional prevalence of the tendency to substitute feeling for 

 thinking, which is a very characteristic feature of general charac- 

 ter where it exists ; (3) varieties in degree and kind of orderli- 

 ness ; (4) differences in the degree of colour-interest, as also of 

 interest in form and number ; (5) great variety in degree and 

 kind of imaginative play, as shown in the efforts of constructive 

 explanation required to describe a picture. — Mr. Joseph Jacobs 

 then read a paper entitled " .A Comparative Estimate of Jewish 

 Ability." In it he applied the same method to Jews and Scotch- 

 men as Mr. Galton had applied to Englishmen in his " Hereditary 

 Genius," with results favourable to the two former races in the 

 order mentioned. The subjects in which Jews seemed to show 

 superior ability were philology, music, metaphysics, and finance. 



Royal Meteorological Society, November 18. — Mr. R. H. 

 Scott, F.R.S., President, in the chair.— Messrs. T. R. H. 

 Clunn, R. S. Davies, B.A., H. C. Fox, M.R.C.S., W. E. 

 Jackson, J. Richardson, M.Inst.C.E., F.G.S., A. L. Rotch, 

 and C. Todd, CM. G., were elected Fellows of the Society. — 

 The following jiapers were read : — The Helm wind of August 

 19, 1885, by William Marriott, F.R.Met.Soc. This wind is 

 peculiar to the Cross Fell range, Cumberland, and is quite 

 local, but very destructive. The chief features of the phenome- 

 non are the following : — On certain occasions when the wind is 

 from some easterly point, the helm suddenly forms. At first a 

 heavy bank of cloud rests along the Cross Fell range, at times 

 reaching some distance down the western slopes, and at others 

 hovering above the summit ; then at a distance of one or two 

 miles from the foot of the Fell there appears a roll of cloud 

 suspended in mid-air and parallel [with the helm cloud : this is 

 the helm bar. A cold wind rushes down the sides of the Fell 

 and blows violently till it reaches a spot nearly underneath the 

 helm bar, where it suddenly ceases. The space between the 

 helm cloud and the bar is usually quite clear, blue sky being 

 visible. At times, however, small portions of thin vaporous 

 clouds are seen travelling from the helm cloud to the bar. The 

 bar does not appear to extend further west than the River Eden. 

 The author visited the district in August last, and was fortunate 

 enough to witness a slight helm. He gives a detailed account 

 of what he experienced, .and also his observations on the tempera- 

 ture of the air at the summit and base of Cross Fell, the direc- 

 tion and force of the wind, the movement of the clouds, &c. — 

 The typhoon origin of the weather over the British Isles during 



