August 3, 1893] 



NA TURE 



-» '» r 



the conclusion which may be drawn is that there is no essential 

 difference between the tissue which will form septum or trabecula 

 and that which will form spores, since they can mutually 

 undergo conversion. 



It has already been shown by others that in Psilotum the 

 number of loculi in the synangium may vary, being sometimes 

 two, normally three, but occasionally four or five. In 

 ; Tmesipteris it may be one, two, or three ; and as there is no 

 jdoubt of the homology of these within the Psilotaceje, we may 

 .conclude that in homologous parts the loculi may vary in number 

 \\fro?n one upivards. 



\ We may recognise within the species Tmesipteris a correlation 

 jof sire to number of loculi ; the smallest specimens have no 

 iseptum, and these are produced at the limits of the fertile zone, 

 'where nutrition may be failing ; those which are of normal size 

 'jhave two loculi : occasional Ij-, when of large size and well 

 flourished, as at the middle of the fertile zone, the loculi may 

 ; |be three. Here is illustrated in one species much the same 

 ^sequence as is seen elsewhere for distinct genera, such as 

 YiLycopodium, Isoetes, Lepidodendron : where the sporangium is 

 S'pmall there are neither trabeculae nor septa, the exigencies of 

 putrition, and perhaps also of mechanical strengthening, not 

 ihem^fe^^ [Lycopodium] : where the sporangium is large sterile 

 pands of tissue are present ; these appear as trabecula? or in- 

 , complete septa Lepidodendron or Isoetes, but as complete septa 

 ■ in the large synangia of Tmesipteris. To those who accept the 

 nomology of the synangium of Tmesipteris with the sporangium 

 \>i other Lycopodinae the probability of this will appear specially 

 Urong. Such facts as these and their theoretical bearing are 

 discussed at length in the memoir : the opinion is finally ex- 

 pressed that progressive sterilisation and formation of septa are 

 actors which will have to be taken into account in solving the 

 iroblems of origin of vascular plants. 



■' Magnetic Qualities of Iron," by J. A. Ewing, M.A., 

 '. li.S., Professor of Mechanism and Applied Mechanics in 

 he University of Cambridge, and Miss Helen G, Klaassen, 

 ,ecturer in Physics, Newnham College. 



The paper describes a series of observations of magnetic 

 uality in various specimens of sheet iron and iron wire. A 

 rmcipal object was to determine the amount of energy lost in 

 nnsequence of magnetic hysteresis when the iron under exam- 

 nation was carried through cyclic magnetising processes. 

 >Iany cycles of B and H were gone through in the case of each 

 f the specimens, the limits between which B was reversed being 

 aried step by step in successive cycles, to allow the relation of 



;nergy expended or of / H</I to B to be determined. The 



;xamined was, for the most part, thin sheet metal or wire 



as is used in the construction of transformer cores. The 



riments show that there are marked differences in the 



mies of j lid I in different specimens, even when all are 

 uminally soft iron. 

 In connection with these results a formula proposed by Mr. 



■ Steinmetz(JH£/I=<rB''«V to express the relation of the 



resis losses to B is discussed, and it is shown that although 



a formula may serve fairly well as an approximate state- 



• of the relation within those limits of B which are important 



practice, it fails when applied to the more extreme portions 



;he curve. 



The authors go on to describe a second group of experiments, 



which direct measurements were made of the heat developed 



niagnetic reversals. The method consisted in using two 



. alike in all respects, with divided magnetising coils. One 



had its coils coupled so that the two parts opposed each 



:, and the core was consequently not magnetised when a 



nt passed. The other ring was active, and its coils (coupled 



lively) were connected in series with the non-inductive 



of the inactive ring. Alternating currents were passed 



igh both, and the active ring became heated by the effects 



teresis and Foucault currents. To balance this a steady 



nt was caused to flow in the core of the inactive ring, 



1 the energy was measured which had to be expended 



this current in order that the temperature of the two 



,igs might continue equal. In some cases the rings used were 



aniature transformers, and no difference was found in the 



' ' "Trans. American Inst, of Electrical Engineers," vol. ix. No. i. 



NO. 1240, VOL. 48] 



amount of energy consumed in the core when the "load" was 

 taken off or put on the secondary. 



In a third group of experiments the magnetic curve tracer 

 was used to examine certain features of the curves of magnetisa- 

 tion. This instrument, invented by one of the authors, draws 

 curves which exhibit the relalion of the magnetisation of given 

 samples of iron or steel to the magnetising current. Amongst 

 other points referred to in this connection is the time-lag in 

 magnetisation, which is shown by the curve tracer to be 

 immensely great in soft thick bars. The work spent per cycle 

 is a maximum at a particular frequency, which in such bars is 

 very low. 



The fourth and last section of the paper relates to the molecu- 

 lar theory of magnetisation, and describes experiments made 

 with groups of small pivoted magnets. Results are given which 

 tend to confirm the theory. 



The particulars of the ob-ervations are set out in about forty 

 sheets of curves which accompany the paper. 



-Sydney. 

 Royal Society of New South Wales, May 3.— Annual 

 Meeting. — Prof. Warren, President, in the chair. — The report 

 stated that thirty-three new members had been elected during 

 the year, and the total number on the roll on April 30 was 477- 

 During the year the Society held eight meetings, at which the 

 following papers were read: — Presidential address. Hail- 

 storms, and is Mars inhabited? by H. C. Russell, F.R. S. — 

 On the importance and nature of the Oceanic languages, by 

 Sidney H. Ray. — On certain geometric.il operations. Part I., 

 by G. Fleuri. — A determination of the magnetic elements at 

 the Physical Laboratory, University of Sydney, by C. Coleridge 

 Farr. — Analyses of some of the well, spring, mineral, and 

 artesian waters of New South Wales, and their probable value 

 for irrigation and other purposes, by John C. H. Mingaye. — 

 Ventilation of sewers and drains, by John M. Small. — Flying- 

 machine work and the 4 I. H. P. steam motor weighing 3^1bs., 

 by Lawrence Hargrave.^The venom of the Australian black 

 snake (Pseudechis porphyriacus), by Dr. C. J. Martin and J. 

 McGarvie Smith. — On the effect which settlement in Australia 

 has produced upon indigenous vegetation, by Alex. G. Hamilton 

 (for which essay the Society's bronze medal and prize of £2$ 

 were awarded). — Some folksongs;and myths from Samoa, trans- 

 lated by the Rev. G. Pratt, with introductions and notes by Dr. 

 John Fraser. — Preliminary note on limestone occurring near 

 Sydney, by Henry G. Smith. — Observations on shell-heaps and 

 shell-beds, significance and importance of the record they afford, 

 by E. J. Statham. — Notes on the recent cholera epidemic in 

 Germany, by Dr. Schwarzbach. — On native copper iodide 

 (Marshite) and other minerals from Broken Hill, New South 

 Wales, by C. W. Marsh. — On the comet in the constellation An- 

 dromeda. — Results of observations of Wolf's Comet (II.), 1891, 

 Swift's Comet (L), 1892, and Winnecke's Periodical Comet, 

 1892, at Windsor, New South Wales, by John Tebbutt.— On 

 the languages of Oceania, by Dr. John Fraser. — Notes on some 

 Australian stone weapons, by Prof. Liversidge, F.R.S. The 

 following papers were read before the various sections, viz. : — 

 Medical Section : Recent work on the pathology of cancer, by 

 Dr. G. E. Rennie. — Notes of a case of hydatid of the brain, by 

 Dr. W. Chisholm. — Notes on a case of sarcoma of the testis in 

 a cryptorchid removal, by Dr. Fiaschi. Engineering Section : 

 Description of the engines recently erected at Ryde Pumping 

 Station, with results of the tests applied, by C. W. Darley. — 

 Various systems of tramway traction, by W. F. How.— Recent 

 bridge-building in New Zealand, by A. H. Alabaster. — Notes 

 on the economical use of steam, by T. H. Houghton. — Light 

 railways for New South Wales, by C. O. Burge. Chemical 

 and Geological Section : An account of a visit tn New Guinea, 

 together with some notes on the community of life between 

 Australia and New Zealand, by Charles Hedley —On the 

 occurrence of platinum and associated minerals in the sands of 

 the Richmond river ; also in the lode material of Broken Hill, 

 by J. C. H. Mingaye. — On a remarkable specimen of auriferous 

 quartz containing fossil encrinites. — An account of some intru- 

 sive rocks in the neighbourhood of Sydney, by Rev. J. Milne 

 Curran. — ^On a new mineral containing iodide of copper found 

 at Broken Hill, by W. M. Hamlet.— The Clarke medal for 

 1893 had been awarded to Prof Ralph Tate, University, 

 Adelaide. The Council had issued the following list of sub- 

 jects, with the offer of the Society's bronze medal and a prize 

 of £21, for each of the best researches, if of sufficient merit, to 



