August 8, 1901] 



NA rURE 



565 



and that the faculty of commerce should not be constituted, or 

 regular teaching begin, until the following session. 



The Royal Commissioners for the Exhibition of 1851 have 

 made the following appointments to science research scholar- 

 ships for the year 1901, on the recommendation of the authori- 

 ties of the several universities and colleges. The scholarships 

 are of the value of 150/. a year, and are ordinarily tenable for 

 two years (subject to a satisfactory report at the end of the first 

 year) in any university at home or abroad, or in some other 

 institution approved of by the Commissioners. The scholars are 

 to devote themselves exclusively to study and research in some 

 branch of science, the extension of which is important to the 

 industries of the country : — J. A. Craw, University of Glasgow ; 

 F. Horton. University of Birmingham ; k. Slator, University 

 of Birmingham ; R. B. Denison, Yorkshire College, Leeds ; G. 

 Owen, University College, Liverpool ; G. Senter, University 

 College, London; F. W. Rixon, Owens College, Manchester ; 

 T. Baker, Durham College of Science, Newcastle-on-Tyne ; 

 S. C. Laws, University College, Nottinghatii ; Alice E. Smith, 

 University College of North Wales, Bangor ; J. Hawthorne, 

 Queen's College, Belfast ; R. K. McClung, McGill University, 

 Montreal; C. W. Dickson, Oueen's University, Kingston, 

 Ontario ; G. Harker, University of Sydney ; Dr. J. M. 

 Maclaren, University of New Zealand. The following scholar- 

 ships granted in 1900 have been continued for a second year on 

 receipt of a satisfactory report of work done during the first 

 year :— C. E. Fawsitt, University of Edinburgh; V. J. Blyth, 

 University of Glasgow; J. Moir,. University of Aberdeen; 

 Dr. VV. M. Varley, Yorkshire College, Leeds ; J. C. \V. 

 Humfrey, University College, Liverpool ; S. Smiles, University 

 College, London ; Alice L. Embleton, University College of 

 South Wales and Monmouthshire, Cardiff ; J. A Cunningham, 

 Royal College of Science, Dublin ; W. S. Mills, Queen's 

 College, Galway ; J. Patterson, University of Toronto ; W. C. 

 Baker, Queen's University, Kingston, Ontario ; J. Barnes, 

 Dalhousic University, Halifax, Nova Scotia ; J. J- E. Dur.ick, 

 University of S)dney. The following scholarships granted in 

 1S9S and 1899 have been exceptionally renewed for a third 

 year : — L. N. G. Filon, University College, London ; J. W. 

 Mellor, University of New Zealand ; F. W. Skirrow, Yorkshire 

 College, Leeds ; C. G. Barkla, University College, Liverpool ; 

 W. Campbell, Durham College of Science, Newcastle-upon- 

 Tyne ; L. Lownds, University College, Nottingham ; Dr. J. T. 

 Jenkins, University College of Wales, Aberystwyth ; R. D. 

 Abell, University College of North Wales, Bangor ; B. D. 

 Steele, University of Melbourne. 



SCIENTIFIC SERIAL. 



American Journal nf Science, July. — Geology of the Shonkin 

 Sag and Palisade Butte Laccoliths in the Highwood Mountains of 

 Montana, by W. W. Weed and L. V. Pirsson. — On the man- 

 ganese ore deposits of the (Jueluz (Lafayette) district, Minas 

 Geraes, Brazil, by O. A. Derby. — On the bituminous deposits 

 situated at the south and east of Cardenas, Cuba, by H. E. 

 Peckham. On the north of Cuba there is a tract of country more 

 than 4500 square miles in area, the springs and wells of which give 

 indications of the existence of liquid bitumens of varying density. 

 The oil which has been obtained resembles the oils of Russia, 

 but it is doubtful if, in view of the enormous production which 

 recent developments in Texas and Indiana promise, there is at 

 present any encouragement for even experimental drilling in 

 Cuba. — Mineralogical notes. No. 2, by .\. F. Rogers. A descrip- 

 tion of new types of calcite and galena, together with a note 

 of new localities for some rare minerals.— -.A new solution 

 for the copper voltameter, by W. K. Shepard. A saturated 

 solution of copper sulphate is boiled for a short time to expel the 

 air and then kept for about an hour at lOO' C. in contact with 

 metallic copper in order to neutralise the solution. About '05 per 

 cent, of ammonium chloride was then added. Using this solution 

 it was found that the weight of copper was practically independent 

 of the temperature between 20' and 40' C ; the solution may be 

 used a large number of times, and the results are independent of 

 the current density between the limits of 02 and '07 ampere 

 per square centimetre. — The thermomagnetic and galvano- 

 magnetic effects in tellurium, by iL G. Lloyd. — Additions to 

 the avifauna of the Bermudas, svith diagnoses of two new 

 subspecies, by A. H. Yerrill. — The induced alternating current 

 discharge studied with reference to its spectrum and especially its 

 ultra-violet spectrum, by A. W. Wright and E. S. Downs. 



NO. 1658, YOL. 64] 



SOCIETIES AND ACADEMIES. 



London. 



Royal Society, May 23. — " Preliminary Statement on the 

 Prothalli of Ophioglossniit pendulum (L. ), Hclminthostachys 

 zeylanica (Hook), and Psilotiim, sp." By William H. Lang, 

 M.B., D.Sc, Communicated by Prof F. O. Bower 

 F.R.S. 



During a recent visit to Ceylon and the Malay Peninsula, the 

 author found prothalli of Ophioglossiim pendulum and Helinin- 

 thoslachys zeylanica as well as a single specimen, which there is 

 reason to regard as the prothallus of Psilotuni. This paper 

 gives a brief account of the mode of occurrence and external form 

 of these three prothalli. 



Ophiogloisuin pendulum. The prothalli were found in the 

 humus collected by an epiphytic fern. They were wholly sapro- 

 phytic, devoid of chlorophyll and of a yellowish-white colour. 

 An endophytic mycorhiza is present in them. The prothallus is 

 radially symmetrical, the older ones consisting of a number of 

 short cylindrical branches radiating in all directions into the 

 humus. The surface of these branches is covered with short 

 unicellular hairs (paraphyses) ; rhizoids are absent. The 

 antheiidia and archegonia, which occur on the same prothallus, 

 resemble those of O. pedunculosum. 



Helminthostachys zeylanica. The wholly saprophytic protha Hi 

 of this plant occur about two inches below the surface of the 

 ground. They are radially symmetrical ; the lower vegetative half, 

 in which is an endophytic lungus, is more or less lobedand bears 

 rhizoids. The sexual organs are borne on the upper half ; the 

 antheridia are large and sunk beneath the surface ; the archegonia 

 project slightly from it. Sometimes the prothalli are moncecious, 

 but more often a prothallus bears antheridia or archegonia only. 

 The ternate lamina of the first leaf of the young plant is green 

 and appears above ground. 



Psilotuin. \ single prothallus, presumably belonging to this 

 plant, was found embedded among the roots covering the stem of 

 a tree-fern. It was one-quarter of an inch long and presented a 

 general resemblance to some prothalli of Lycopodtum, having a 

 well-marked primary tubercle. The sexual organs were borne 

 on the overhanging margin of the upper region of the pro- 

 thallus, between which and the lower vegetative region the 

 meristem will probably be found to be situated. 



June 20. — "The Mechanism of the Electric Arc." By 

 (^irs. ) Hertha Ayrton. Communicated by Prof. Perry, 

 F.R.S. 



The object of the paper is to show that, by applying the 

 ordinary laws of resistance, of heating and cooling and of 

 burning to the arc, considered as a gap in a circuit furnishing 

 its own conductor by the volatilisation of its own material, all 

 its principal phenomena can be accounted for, without the aid 

 of a large back E. M.F. , or of a " negative resistance," or of any 

 other unusual attribute. 



The Apparent Large Back E.M.F. 



It is shown how volatilisation may begin, even without the 

 self-induction to which the starting of an arc, when a circuit is 

 broken, is usually attributed ; and it is pointed out that, when 

 the carbons are once separated, all the material in the gap cannot 

 retain its high temperature. The air must cool some of it into 

 carbon nnst or fog, just as the steam issuing from a kettle is 

 cooled into water mist at a short distance from its mouth. The 

 dissimilar action of the poles common to so many electric 

 phenomena displays itself in the arc at this point. Instead of 

 both poles volatilising the positive pole alone does. It is con- 

 sidered, therefore, that the arc consists of (i) a thin layer of 

 carbon vapour issuing from the end of the positive carbon, (2) a 

 bulb of carbon mist joining this to the negative carbon, and (3) a 

 sheath of burning gases, formed by the burning of the mist, and 

 the hot ends of the carbons, and surrounding both. The vapour 

 appears to be indicated in images of the arc by a sort of gap 

 between the arc and the positive carbon, the mist by a purple 

 bulb and the gases by a green flame. 



The flame is found to be practically insulating, so that nearly 

 the whole of the current flows through the vapour and mist 

 alone. It is suggested that the vapour has a high specific 

 resistance compared with that of the mist, and that it is to the 

 great resistance of this vapour-film that the high temperature of 

 the crater is due, and not to any large back E..\I.F. of which it 

 is the seat. 



